Anterior communicating artery aneurysm endovascular treatment complications
Intraprocedural aneurysm rupture and thrombus formation are serious complications during coiling of ruptured intracranial aneurysms, and they more often occur in patients with anterior communicating artery aneurysms.
It is associated with a high rate of complete angiographic occlusion. However, the procedure-related permanent morbidity and mortality are not negligible for aneurysms in this location 1).
Between March 1994 and October 2021, 648 consecutive cerebral aneurysms were treated by the endovascular procedure. Medical records were reviewed retrospectively with emphasis on procedure description, potential risk factors, and clinical outcomes related to intra- or peri-procedural rupture.
Of the 648 patients, 17 (2.6%) suffered an intra- or peri-procedural hemorrhagic event. The most common location was the anterior communicating artery. There was no significant difference between previously ruptured and unruptured aneurysms in the incidence of bleeding. In four patients, bleeding was evident within 24 h after the procedure. The clinical evolution at three months was poor and only four patients presented a positive evolution. There were 11 deaths (64.71%). Balloon remodeling was associated with an increased frequency of ruptures, while stenting was a safer treatment.
Aneurysm rupture during endovascular therapy is unpredictable, and its occurrence can be devastating. The incidence is quite low although the outcome is frequently poor. Early detection and proper management, including prompt occlusion of the aneurysm, are important to achieve a positive outcome. Anterior communicating artery aneurysms and those treated with balloon catheters have a higher incidence of rupture. A small number of ruptures of uncertain origin occur that go unnoticed in digital subtraction angiograms 2).
The immediate and long-term outcomes, complications, recurrences and the need for retreatment were analyzed in a series of 280 consecutive patients with anterior communicating artery aneurysms treated with the endovascular technique. From October 1992 to October 2001 280 patients with 282 anterior communicating artery aneurysms were addressed to our center. For the analysis, the population was divided into two major groups: group 1, comprising 239 (85%) patients with ruptured aneurysms and group 2 comprising of 42 (15%) patients with unruptured aneurysms. In group 1, 185 (77.4%) patients had a good initial pre-treatment Hunt and Hess grade of I-III. Aneurysm size was divided into three categories according to the larger diameter: less than 4 mm, between 4 and 10 mm and larger than 10 mm. The sizes of aneurysms in groups 1 and 2 were identical but a less favorable neck to depth ratio of 0.5 was more frequent in group 2. Endovascular treatment was finally performed in 234 patients in group 1 and 34 patients in group 2. Complete obliteration was more frequently obtained in group 2 unlike a residual neck or opacification of the sac that were more frequently seen in group 1. No peri-treatment complications were recorded in group 2. In group 1 the peri-treatment mortality and overall peri-treatment morbidity were 5.1% and 8.1% respectively. Eight patients (3.4%) in group 1 presented early post treatment rebleeding with a mortality of 88%. The mean time to follow-up was 3.09 years. In group 1, 51 (21.7%) recurrences occurred of which 14 were minor and 37 major. In group 2, eight (23.5%) recurrences occurred, five minor and three major. Two patients (0.8%) presented late rebleeding in group 1. Twenty-seven second endovascular retreatments were performed, 24 (10.2%) in group 1 and three (8.8%) in group 2, seven third endovascular retreatments and two surgical clippings in group 1 only. There was no additional morbidity related to retreatments. Endovascular treatment is an effective method for the treatment of anterior communicating artery aneurysms allowing late rebleeding prevention. Peri-treatment rebleeding warrants caution in anticoagulation management. This is a single center experience and the follow-up period is limited. Patients should be followed-up in the long-term as recurrences may occur and warrant additional treatment 3).
LVIS stent-assisted coiling for ruptured wide-necked ACoA aneurysms was safe and effective, with a relatively low rate of perioperative complications and a high rate of complete occlusion at follow-up 5)
terior communicating artery aneurysm endovascular treatment complications
Unruptured anterior communicating artery aneurysm rupture risk
Although the research on the risk factors of anterior communicating artery aneurysm has made great progress, the independent effect of each risk factor on the rupture of AComA aneurysm is controversial among different studies. For this answer Xie et al. will present the results employing the random effects model. Quality assessment of the included studies will be evaluated using the Newcastle–Ottawa Scale. Statistical analyses will be performed using Stata16 (Stata Corporation, College Station, TX, USA) software.The findings of this study will be submitted to peer-reviewed journals for publication. This systematic review will provide evidence to determine the risk factors that affect the rupture of the AComA aneurysm and quantify their independent effects 1).
Ma et al. found that larger size, greater size ratio, larger flow angle, irregular shape, and smoking of the patient were associated with the rupture of ACoA aneurysms based on univariate analysis. Size ratio (OR = 3.890, P = 0.003), irregular shape (OR = 1.068, P = 0.001), flow angle (OR = 1.054, P = 0.001), and current smoking (OR = 4.435, P = 0.009) were the strongest factors related to ruptured ACoA aneurysms based on multivariate logistic regression analysis. The areas under the curves for the flow angle and size ratio were 0.742 (95% CI 0.646-0.838; P = 0.001) and 0.736 (95% CI 0.621-0.796; P = 0.001), respectively. The strongest risk factors for rupture include size ratio, irregular shape, flow angle, and current smoking. These features should be taken into consideration to aid in the prediction of the rupture risk of ACoA aneurysms 2).
Multiple logistic regression model revealed that A1 dominance [odds ratio (OR) 3.034], an irregular shape (OR 3.358), and an aspect ratio ≥1.19 (AR; OR 3.163) increased the risk of rupture, while cerebral atherosclerosis (OR 0.080), and mean diameters ≥2.48 mm (OR 0.474) were negatively correlated with ACoAA rupture. Incorporating these five factors, the ROC analysis revealed that the threshold value of the multifactors was one, the sensitivity was 88.3%, and the specificity was 66.0%. The scoring model is a simple method that is based on A1 dominance, irregular shape, aspect ratio, cerebral atherosclerosis, and mean diameters from CTA and is of great value in the prediction of the rupture risk of ACoAAs 3).
According to the International Study of Unruptured Intracranial Aneurysms (ISUIA), anterior circulation (AC) aneurysms of <7 mm in diameter have a minimal risk of rupture. It is general experience, however, that anterior communicating artery (AcoA) aneurysms are frequent and mostly rupture at <7 mm. Bijlenga et al. found that AC aneurysms are not a homogenous group. Aneurysms between 4 and 7 mm located in AcoA or distal anterior cerebral artery present similar rupture odds to posterior circulation aneurysms. Intervention should be recommended for this high-risk lesion group 4).
For Matsukawa et al. the anterior projection of an ACoA aneurysm may be related to rupturing. The authors would perhaps recommend treatment to patients with unruptured ACoA aneurysms that have an anterior dome projection, a bleb(s), and a size ≥ 5 mm 5).
Aneurysms found unruptured in the ACoA show a risk of rupture twice as high as that of other intracranial aneurysms (95% confidence interval, 1.29-3.12). It is the first time this fact has been demonstrated based on the follow-up of unruptured aneurysms.
When deciding whether to operate on UIAs located in the ACoA, surgeons should consider their higher risk of rupture 6).
Anosmia after anterior communicating artery aneurysm surgery
For Bor et al. anosmia occurs after coiling in 1 of every 6 SAH patients, but has a good prognosis in most patients. The cause of anosmia after coiling for ruptured aneurysms remains elusive; severity of the initial hemorrhage or long lasting hydrocephalus may be contributing factors 1).
In patients with subarachnoid hemorrhage (SAH), anosmia has mainly been reported after surgery for anterior communicating artery aneurysms. Olfactory dysfunction after SAH caused by rupture of the ACoA are very frequent and were present in both treatment groups (aneurysmal clip placement and coil embolization).
Both clip treatment and SAH contribute to the occurrence of anosmia, with different chances of improvement. Olfactory dysfunction occurs in almost all patients on the side of surgery and can occur subclinically after coil deployment 3).
Its occurrence after coiling suggests not only damage to the olfactory nerve by clipping but also that the SAH itself plays a role in its pathogenesis 4).
The highest incidence of olfactory dysfunction following a pterional approach and its modifications for an intracranial aneurysm has been reported in cases of anterior communicating artery (ACoA) aneurysms. The radiological characteristics of unruptured ACoA aneurysms affecting the extent of retraction of the frontal lobe and olfactory nerve were investigated as risk factors for postoperative olfactory dysfunction. In cases of unruptured ACoA aneurysm surgery, the height of the aneurysm neck and the estimated extent of brain retraction were both found to be powerful predictors of the occurrence of postoperative olfactory dysfunction. 5).
Wongsuriyanan and Sriamornrattanakul published that the interhemispheric approach provided an excellent surgical corridor for clipping anterior communicating artery aneurysms (AcoAAs). However, an important disadvantage of the approach is obtaining proximal control at A1 in the last stage of dissection, especially in anterior or superior projecting AcoAAs and ruptured cases.
For Ito et al. the causes of postoperative anosmia in subfrontal and interhemispheric approach were as follows: sectioning of olfactory tracts intentionally or not, avulsion of olfactory bulbs and probability of ischemic or minor mechanical insults to olfactory tracts. However, these matters rarely occur in posterior interhemispheric approach because of little exposure of olfactory nerves. The mechanisms of postoperative anosmia in posterior interhemispheric approach were considered to be as follows: sinking of frontal lobes due to excessive drainage of cerebrospinal fluid and over-retraction of frontal lobes. The incidence of postoperative anosmia decreased from 27.0% via subfrontal and interhemispheric approach to 5.5% via posterior interhemispheric approach 7).
Superior direction of aneurysm appears associated with postoperative olfactory dysfunction. Olfactory protection using gelfoam and fibrin glue could be a simple, safe, and useful method to preserve olfactory function during A-com aneurysm surgery. 8).
For Aydin et al. the functions of olfactory nerve could be preserved at a relatively high rate of 85 per cent. This high rate resulted from the microtechnique employed as well as the relatively cautious frontal lobe retraction which was less than 1.5 cm 9).
For Fujiwara et al. Unilateral dural incision and unilateral brain retraction without elevation of the frontal lobe from the frontal base are important, because frontal lobe depression and elevation during surgery may injure the olfactory nerve 10).
Olfactory dysfunction has an important impact on quality of life. Recovery after traumatic anosmia has been recorded up to 5 years after injury. Nevertheless, the authors believe that the damage is permanent when lasting 35 months or longer 11).
The interhemispheric approach (IHA) provides an excellent surgical corridor for clipping anterior communicating artery aneurysms (AcoAAs). However, an important disadvantage of the approach is obtaining proximal control at A1 in the last stage of dissection, especially in anterior or superior projecting AcoAAs and ruptured cases. Wongsuriyanan and Sriamornrattanakul described and evaluated the microsurgical clipping of AcoAAs using the IHA with early A1 exposure.
This was a retrospective descriptive study in patients with AcoAA who received microsurgical clipping through the IHA with early A1 exposure between April 2016 and May 2019. Aneurysm morphology, projection, completeness of clipping, surgical complications, and outcomes were collected from medical records.
Twenty-five patients with AcoAA received microsurgical clipping via the IHA with early A1 exposure. Twenty-three patients (92%) presented with subarachnoid hemorrhage. Intraoperative rupture while dissecting the interhemispheric fissure occurred in 2 cases, for which proximal control via subfrontal route was effectively performed. Of the patients, 100% achieved complete obliteration of their aneurysms. Postoperative anosmia was detected in 22.7%. In ruptured cases, 16 (88.9%) of the good grade patients achieved a good outcome (Glasgow Outcome Scale scores of 4 and 5) at 3 months after the operation.
The IHA with early A1 is safe and effective for clipping AcoAAs. 12).
Hendrix et al. assessed the risk for olfactory dysfunction following surgical treatment of unruptured cerebral aneurysm via the supraorbital minicraniotomy. A retrospective review of patients with electively treated cerebral aneurysms who underwent perioperative assessment of olfactory function using a sniffin’ sticks odor identification test between January 2015 and January 2016 was performed. A subgroup of patients without history of subarachnoid hemorrhage, without prior intracranial aneurysm treatment, and confirmed olfactory function underwent supraorbital keyhole craniotomy for aneurysm clipping. Microscopic and endoscopic videos were reviewed for this subgroup. Sixty-four patients who underwent elective aneurysm treatment either via surgical clipping or endovascular aneurysm obliteration were identified. Prior to treatment, 4/64 (6.3%) demonstrated bilateral anosmia. Collectively, 14 patients (21.9%) met subgroup criteria of supraorbital keyhole craniotomy for aneurysm clipping. Here, olfactory performance significantly decreased postoperatively on the side of craniotomy (ipsilateral, P = 0.007), whereas contralateral and bilateral olfactory function remained unaltered (P = 0.301 and P = 0.582, respectively). Consequently, 4/14 patients (28.6%) demonstrated ipsilateral anosmia 3 months after surgery. One patient (1/14, 7.1%) also experienced contralateral anosmia resulting in bilateral anosmia. Intraoperative visualization of the olfactory tract and surgical maneuvers do not facilitate prediction of olfactory outcome. The supraorbital keyhole craniotomy harbors a specific risk for unilateral olfactory deterioration. Lack of perioperative olfactory assessment likely results in underestimation of the risk for olfactory decline. Despite uneventful surgery, prediction of postoperative olfactory function and dysfunction remain challenging 13).
A total of 63 patients (aged 41-79 yr, mean 64 yr) with relatively small AcomA aneurysms clipped via the lateral supraorbital approach were retrospectively analyzed among the 105 AcomA aneurysms treated by clipping from 2005 to 2014. Neurological and cognitive functions were examined by several scales, including the modified Rankin Scale (mRS) and Mini-Mental Status Examination. The depressive state was assessed using the Beck Depression Inventory and Hamilton Depression Scale. The state of clipping was assessed 1 yr and then every few years after the operation by 3-dimensional computed tomography angiography.
Complete aneurysm neck clipping was confirmed in 62 aneurysms (98.4%). Perioperative complications occurred in 5 patients (5/63; mild frontalis muscle weakness in 3, anosmia in 1, and meningitis in 1). The mean clinical follow-up period was 5.2 ± 2.1 yr. No patient showed an mRS score more than 2 and all were completely independent in daily life. The depression scores were significantly improved after surgery. The overall mortality was 0% and overall morbidity (mRS score > 2 or Mini-Mental Status Examination score < 24) was 1.6%. All completely clipped aneurysms did not show any recurrence during the mean follow-up period of 4.9 ± 2.1 yr.
Cho et al. retrospectively reviewed the medical records of patients who underwent surgical clipping for unruptured aneurysm from 2011-2013 by the same senior attending physician. Since March 2012, olfactory protection using gelfoam and fibrin glue was applied in A-com aneurysm surgery. Therefore we categorized patients in two groups from this time-protected group and unprotected group.
Of the 63 enrolled patients, 16 patients showed postoperative olfactory dysfunction-including 8 anosmia patients (protected group : unprotected group=1 : 7) and 8 hyposmia patients (protected group : unprotected group=2 : 6). Thirty five patients who received olfactory protection during surgery showed a lower rate of anosmia (p=0.037, OR 10.516, 95% CI 1.159-95.449) and olfactory dysfunction (p=0.003, OR 8.693, 95% CI 2.138-35.356). Superior direction of the aneurysm was also associated with a risk of olfactory dysfunction (p=0.015, OR 5.535, 95% CI 1.390-22.039).
Superior direction of aneurysm appears associated with postoperative olfactory dysfunction. Olfactory protection using gelfoam and fibrin glue could be a simple, safe, and useful method to preserve olfactory function during A-com aneurysm surgery. 15).
The highest incidence of olfactory dysfunction following a pterional approach and its modifications for an intracranial aneurysm has been reported in cases of anterior communicating artery (ACoA) aneurysms. The radiological characteristics of unruptured ACoA aneurysms affecting the extent of retraction of the frontal lobe and olfactory nerve were investigated as risk factors for postoperative olfactory dysfunction.
Methods: A total of 102 patients who underwent a pterional or superciliary keyhole approach to clip an unruptured ACoA aneurysm from 2006 to 2013 were included in this study. Those patients who complained of permanent olfactory dysfunction after their aneurysm surgery, during a postoperative office visit or a telephone interview, were invited to undergo an olfactory test, the Korean version of the Sniffin’ Sticks test. In addition, the angiographic characteristics of ACoA aneurysms, including the maximum diameter, the projecting direction of the aneurysm, and the height of the neck of the aneurysm, were all recorded based on digital subtraction angiography and sagittal brain images reconstructed using CT angiography. Furthermore, the extent of the brain retraction was estimated based on the height of the ACoA aneurysm neck.
Results: Eleven patients (10.8%) exhibited objective olfactory dysfunction in the Sniffin’ Sticks test, among whom 9 were anosmic and 2 were hyposmic. Univariate and multivariate analyses revealed that the direction of the ACoA aneurysm, ACoA aneurysm neck height, and estimated extent of brain retraction were statistically significant risk factors for postoperative olfactory dysfunction. Based on a receiver operating characteristic (ROC) analysis, an ACoA aneurysm neck height > 9 mm and estimated brain retraction > 12 mm were chosen as the optimal cutoff values for differentiating anosmic/hyposmic from normosmic patients. The values for the area under the ROC curves were 0.939 and 0.961, respectively.
Conclusions: In cases of unruptured ACoA aneurysm surgery, the height of the aneurysm neck and the estimated extent of brain retraction were both found to be powerful predictors of the occurrence of postoperative olfactory dysfunction. 16).
Matano et al. presented a fibrin-gelatin fixation method that provides reinforcement and moisture to help preserve the olfactory nerve when using the anterior interhemispheric approach and describe the results and outcomes of this technique. We analyze the outcomes with this technique in 45 patients who undergo surgery for aneurysms, brain tumors, or other pathologies via the anterior interhemispheric approach. Anosmia occurred in 4 patients (8.8%); it was transient in 2 (4.4%) and permanent in the remaining 2 (4.4%). Brain tumors clearly attached to the olfactory nerve were resected in the patients with permanent anosmia. We found a significant difference in the presence of anosmia between patients with or without lesions that were attaching the olfactory nerve (p = 0.011). Our results suggested that fibrin-gelatin fixation method can reduce the reported risk of anosmia. However, the possibility of olfactory nerve damage is relatively high when operating on brain tumors attaching olfactory nerve 17).
Lai et al. presented the operative experiences in a consecutive series of 103 patients with 115 unruptured AcomA aneurysms. Clinical results, operative complications, angiographic outcomes and prognostic factors associated with surgery are presented. Of the 115 aneurysm repairs attempted, 114 were treated by clipping or excision and suture. One aneurysm, less than 2mm, was wrapped. Six patients (5.8%; 95% confidence interval [CI], 2.5-12.4) experienced a new permanent neurological deficit. There was no postoperative mortality. Transient morbidity occurred in 11 patients (10.7%; 95% CI, 5.9-18.3), including transient anosmia (four patients), acute postoperative confusion and memory disturbances (four patients), extradural haematoma requiring surgery (two patients) and cerebrospinal fluid rhinorrhea (one patient). Of the 84 aneurysms (73.0%) that had documented postoperative angiography, 82 (97.6%) had complete obliteration of the aneurysm and two (2.4%) had neck remnants (mean angiographic follow-up 28.0 months; range, 1.6-146.4 months). Retreatment was performed in one patient (1.0%). Logistic regression analysis of risk factors revealed that aneurysm size (p<0.01) was a significant predictor of outcome. There was no incidence of subarachnoid haemorrhage in the 272 person years of follow-up. In the current study, surgical treatment of unruptured AcomA aneurysms resulted in 5.8% morbidity and no mortality. The robustness of aneurysm repair achieved by open microsurgery is an important consideration when considering the option between endovascular and microsurgical treatment for unruptured AcomA aneurysms. 18).
Nakayama et al. studied the incidence of postoperative infection related to CSF leakage and anosmia in basal interhemispheric approach (BIH). Between April, 1990 to March, 2009, 142 cases of anterior communicating (Acom) aneurysm including both unruptured and ruptured have been treated by clipping surgery using BIH. We retrospectively obtained clinical informations from medical records and video records about infectious complications, CSF leakage of cerebrospinal fluid (CSF), olfactory dysfunction and intraoperative findings of damage to the olfactory nerve. In most cases (139 patients, 97%), frontal sinus were opened at craniotomy. Of all, CSF rinorrhea occurred in 4 cases (2.8%), and meningitis in 6 cases. There was only one patient who sufferd from meningitis due to CSF rinorrhea. All that patients recovered completely without deficit. Anosmia occurred in 6 cases (4.2%), and intraoperative injuries in 4 cases (2.8%). There was only one patient in whom anosmia was consistent with nerve injury. In conclusion, BIH is an appropriate procedure for infection risk control in Acom aneurysm surgery. It is difficult to avoid olfactory dysfunction completely, even if olfactory nerves are preserved in form. 19).
The horizontal head position was adopted in the unilateral anterior interhemispheric approach to treat an anterior communicating artery (ACoA) aneurysm. The patient was placed in the supine position. The patient’s head was rotated to the right to orient the midline horizontally, and tilted 45 degrees superiorly. After bicoronal skin incision and bifrontal craniotomy, the dura on the right side (downside) was opened. Dissection of the right interhemispheric fissure allowed gravity to retract the right (downside) hemisphere, which fell away from the falx, while the falx supported the upside hemisphere. The present approach was used in three patients with ACoA aneurysm between January 2009 and April 2010. The aneurysms were adequately clipped with this approach. No complication related to the approach occurred. No patients exhibited anosmia after surgery. This approach is useful for ACoA aneurysms. 20).
Beseoglu et al. in 2003 introduced a minimally invasive transorbital keyhole approach. Because this approach requires removal of the orbital rim and orbital roof, there have been concerns regarding perioperative morbidity, long-term morbidity, and cosmetic results. The authors evaluated approach-related morbidity and cosmetic results in their patients to determine the rate of complications and compared this to published reports of similar approaches.
Material: Seventy-one patients (41 female, 30 male) underwent operations using this approach between 2004 and 2008. Immediate approach-related morbidity was recorded after the operation. Late morbidity was determined after 7 months by an independent examiner while cosmetic results were self-rated by the patient using a questionnaire.
Results: Fifty-one (72%) of 71 patients had no postoperative complications and 12 (16.9%) had minor complications, the most common of which was subgaleal CSF collection (7.0%). Other minor complications included facial nerve palsy (2.8%), hyposphagma (2.8%), periorbital swelling due to periorbital hematoma (2.8%), and subdural hematoma (1.4%). Major complications requiring surgical revision occurred in 4 patients (5.6%); these were CSF fistulas in 2 patients, pneumocephalus in 1 patient, and a hematoma in 1 patient. Forty-nine (90.7%) of all 54 examined patients rated the cosmetic results as very good or good. Major long-term morbidity was hyposmia or anosmia (14 patients) followed by hypoesthesia around the scar (9 patients).
The transorbital keyhole approach is a feasible approach with a low-risk profile for postoperative or long-term morbidity and excellent cosmetic outcome 21)
Although the frequency of smell disorders after the operations of the anterior communicating artery aneurysm depends to a large degree on the used surgical approach, several independent of surgery factors may contribute to the postoperative smell tests outcome. THE AIM OF OUR STUDIES: The evaluation of the sense of smell in patients who underwent the operation of ruptured anterior communicating artery aneurysm using pterional approach.
Material and methods: In the retrospective studies the results of smell test of the group of 21 patients operated for ruptured anterior communicating artery aneurysm and 21 healthy volunteers of control group were compared. The patients suffering from neurodegenerative, metabolic and endocrynological disorders, as well as those with rhinoscopic symptoms of rhinosinusitis and with decreased nasal potency confirmed by anterior rhinomanometry were excluded from the study.
Results: During the operations it was possible to anatomically retain olfactory nerves in all operated patients. Severe smell disorders (severe hyposmia and anosmia) were detected in 1 (4.7%) patient of the control group and in 6 (28.5%) patients of postoperative group. The mean composite olfactory score in Cain test of the postoperative group was 4.53, and in the control group 5.47 points. The difference did not reach statistic significance (Mann-Whitney test, p = 0.068).
Conclusions: Although pterional approach to anterior communicating artery is relatively low traumatic to olfactory tract, the subarachnoid hemorrhage may have an unfavorable effect on postoperative olfactory nerve functioning. Considering the fact, that in spite of thorough examination of the patients, we were not able to exclude from the studied groups all the patients with preoperatively impaired smell, it seems reasonable to perform similar smell test studies in the prospective way 22).
Bor et al. interviewed all patients who resumed independent living after SAH treated with coiling between 1997 and 2007. We assessed by means of logistic regression analyses whether risk of anosmia was influenced by site of the ruptured aneurysm, neurological condition on admission, amount of extravasated blood, hydrocephalus, and treatment for hydrocephalus.
Of 197 patients, 35 (18%; 95%CI:12 to 23) experienced anosmia. Anosmia had improved in 23 (66%) of them; in 20 the recovery had been complete after a median period of 6 weeks (SD +/-6.5). Intraventricular hemorrhage was a risk factor for anosmia (OR 2.4; 95%CI:1.0 to 5.9). Anterior aneurysm location (OR 1.1; 95%CI:0.5 to 2.3) and high amount of extravasated blood (OR 0.9; 95%CI:0.4 to 2.1) were not related to anosmia.
Anosmia occurs after coiling in 1 of every 6 SAH patients, but has a good prognosis in most patients. The cause of anosmia after coiling for ruptured aneurysms remains elusive; severity of the initial hemorrhage or long lasting hydrocephalus may be contributing factors. 23).
Martin et al. studied whether and how frequently patients with ACoA aneurysms present with smell identification deficits in 2 treatment groups (endovascular and surgical treatment).
Methods: A prospective study was conducted of patients with SAH caused by ruptured ACoAs and who had a Glasgow Outcome Scale score of 1 or 2, in comparison with a control group matched by age and sex. Olfactory function was assessed using the University of Pennsylvania Smell Identification Test (UPSIT).
Results: A total of 39 patients were enrolled. A marked olfactory impairment was observed in patients with ruptured ACoAs compared with the control group (p < 0.001). Seventeen patients with ruptured ACoAs (44%) compared with 1 patient in the control group (3%) showed a smell identification deficit according to performance on the UPSIT (p < 0.001). Both groups that underwent treatment presented with olfactory impairment. Ten (59%) of 17 patients who underwent aneurysmal clip placement versus 6 (28.5%) of 21 patients who underwent coil embolization scored below the 25th percentile on the UPSIT, and surgical patients also performed worse than endovascular patients (p = 0.048). The authors observed a worse performance on the olfactory test in patients subjected to endovascular coil embolization when cerebral vasospasm (p = 0.037) or frontal cerebral lesions (p = 0.009) were present. This difference was not observed in patients who underwent surgery.
Conclusions: Olfactory disorders after SAH caused by rupture of the ACoA are very frequent and were present in both treatment groups. Cerebral vasospasm and frontal lobe lesions are related to worse performance on an olfactory test in patients undergoing endovascular coil embolization 24).
To discriminate between the effects of aneurysmal rupture and treatment, Moman et al. assessed the occurrence of anosmia after clipping and coiling of unruptured aneurysms as well as after the coiling of ruptured aneurysms.
Methods: The authors interviewed patients in whom an unruptured aneurysm was treated by clipping (32 cases) or endovascular coiling (26 cases) as well as patients with SAH who underwent coil therapy (32 cases). A geographically defined subset of 20 patients per group was invited to undergo olfactory testing.
Results: Nine clip-treated patients (28% [95% CI 14-47%]) in the unruptured group reported having anosmia, and no coil-treated patient in the unruptured group (95% [CI 0-13%]) reported having anosmia; in the SAH group, 7 patients (22% [95% CI 9-40%]) reported having anosmia. Anosmia had improved over time in 3 of the clip-treated patients and in all but 1 of the patients with SAH. Examination revealed olfactory disturbance in 13 (65% [95% CI 41-85%]) of the clip-treated and 8 (42% [95% CI 20-67%]) of the coil-treated patients with unruptured aneurysms, and also in 7 (35% [95% CI 15-59%]) coil-treated patients with SAH. In 20 patients who underwent clip therapy for unruptured aneurysms, 19 (95% [95% CI 75-100%]) had olfactory dysfunction on the side ipsilateral to surgery (anosmia reported by 8 of them).
Conclusions: Both clip treatment and SAH contribute to the occurrence of anosmia, with different chances of improvement. Olfactory dysfunction occurs in almost all patients on the side of surgery and can occur subclinically after coil deployment. 25).
Wermer et al. studied the prevalence, predisposing factors (aneurysm site and type of treatment), impact, and prognosis of anosmia in patients with SAH.
Of the patients with SAH who resumed independent living, we included all patients treated by coiling between 1997 and 2003 and a sample of patients treated by clipping between 1985 and 2001. Patients underwent structured interviews regarding the presence and duration of anosmia. The impact of anosmia was scored using a visual analog scale ranging from 0 (no influence) to 100 (the worst thing that ever happened to them). Risk factors for anosmia were assessed by logistic regression analysis.
Overall, 89 of the 315 interviewed patients (28%; 95% confidence interval [CI], 23-34%) reported anosmia after SAH (mean follow-up period, 7.4 yr), including 10 (15%) of the 67 coiled patients and 79 (32%) of the 248 clipped patients. The median visual analog scale impact score was 53 (range, 0-100). In 20 of the 89 patients (23%; 95% CI, 15-33), the symptoms had improved over time. Risk factors for anosmia were treatment by clipping (odds ratio [OR], 2.7; 95% CI, 1.3-5.7) and anterior communicating artery aneurysms (OR, 2.0; 95% CI, 1.2-3.3).
Anosmia after SAH has a high prevalence, considerable impact, and poor prognosis. Its occurrence after coiling suggests not only damage to the olfactory nerve by clipping but also that the SAH itself plays a role in its pathogenesis. 26)
Nozaki et al. described a patient with bilateral persistent primitive olfactory arteries associated with an unruptured saccular aneurysm on the left persistent primitive olfactory artery. Seven reported cases with this anomalous artery including ours are reviewed and classified into two variants. This anomalous artery arises from the terminal portion of the internal carotid artery and courses anteromedially along the ipsilateral olfactory tract and makes a hair-pin curve posterior to the olfactory bulb, becoming the distal anterior cerebral artery (variant 1) or the ethmoidal artery (variant 2). Out of 7 reported cases, 4 cases are associated with saccular aneurysms. The aneurysm in variant 1 is located on the hair-pin curve at which an apparent arterial branch is sometimes absent. Two patients suffer from anosmia. Persistent primitive olfactory artery should be kept in mind because of its high association with intracranial saccular aneurysms and unique clinical presentation. 27).
In as retrospective study, 100 patients with anterior communicating artery aneurysms, for whom the pterional approach was employed, were observed from the point of view of postoperative olfactory nerve function. In the postoperative period only three cases suffered from the impaired sense of smell ipsilateral to the side of surgery. 15 patients objectively showed olfactory nerve distinctions. The functions of olfactory nerve could be preserved at a relatively high rate of 85 per cent. This high rate resulted from the microtechnique employed as well as the relatively cautious frontal lobe retraction which was less than 1.5 cm. 28).
Between 1969 and 1994 we treated 450 patients with ruptured anterior communicating artery aneurysms, of which 434 cases (96.4%) were operated on via the interhemispheric approach (IH), namely, until 1979 mainly, via bifrontal craniotomy, subfrontal and interhemispheric approach (SIH) and, since 1979, via posterior interhemispheric approach (PIH). Postoperative olfactory dysfunction is one of the main disadvantages of IH. The mechanisms and the incidence of this disadvantage were studied in both approaches. The causes of postoperative anosmia in SIH were as follows: sectioning of olfactory tracts intentionally or not, avulsion of olfactory bulbs and probability of ischemic or minor mechanical insults to olfactory tracts. However, these matters rarely occur in PIH because of little exposure of olfactory nerves. The mechanisms of postoperative anosmia in PIH were considered to be as follows: sinking of frontal lobes due to excessive drainage of cerebrospinal fluid and over-retraction of frontal lobes. The incidence of postoperative anosmia decreased from 27.0% via SIH to 5.5% via PIH 29).
The olfactory function could be examined in 101 of 138 patients with anterior communicating artery aneurysms, whom we treated during a recent 6-year period. Among them, 49 patients underwent surgery by the anterior interhemispheric approach and 52 underwent surgery by the basal interhemispheric approach. Fifteen patients (31%) exhibited anosmia after surgery by the anterior interhemispheric approach, whereas only one patient (1.9%) exhibited anosmia after surgery by the basal interhemispheric approach. Unilateral dural incision and unilateral brain retraction without elevation of the frontal lobe from the frontal base are important, because frontal lobe depression and elevation during surgery may injure the olfactory nerve 30).
Yasui et al. reviewed the surgical outcome in 85 patients with ruptured anterior communicating artery (ACoA) aneurysms, who were operated on within 72 hours of onset via a basal interhemispheric (BIH) approach (Group 1, N = 48), or an anterior interhemispheric (AIH) approach (Group 2, N = 37). The age, sex ratio and pre-operative grade (Gr) were similar for both groups. The outcome at the time of discharge was as follows for group 1: excellent or good 88%; fair, 6%; vegetative state, 2% and death 4%. For group 2, it was: excellent or good 78%; fair, 16%; vegetative state, 3%; and death, 3%. A significant correlation between admission grade and outcome was found in both groups. The outcome in group 1 was better than in group 2 for patients with a Glasgow Outcome Scale (GOS) better than fair (p < 0.07). No patient in group 1 had postoperative anosmia, but nine patients in group 2 became anosmic. The total number of complications was also significantly less in group 1. Our overall mortality rate was 4%. In conclusion, the BIH approach was more beneficial for treating acute ACoA aneurysm. 31).
In a retrospective study of 25 patients operated on for ruptured intracranial aneurysms via the frontotemporal route, 22 patients suffered postoperatively from anosmia ipsilateral to the side of surgery. This complication most often goes unrecognized by the patient as well as the physician, and attention should be drawn to it because of its widespread occurrence. This investigation demonstrates a high incidence of anosmia (24 (88.9%) of 27 surgical sides) occurring ipsilateral to the frontotemporal approach in aneurysm surgery. Recovery after traumatic anosmia has been recorded up to 5 years after injury. Nevertheless, the authors believe that the damage is permanent when lasting 35 months or longer 32)
Anterior communicating artery aneurysm endovascular treatment
Endovascular treatment has been increasingly performed due to the fact that it is less likely to cause high dysfunction compared to surgery and the treatment has been improved. The International Subarachnoid Aneurysm Trial reported anterior communicating artery aneurysms to comprise 45.4% of cerebral aneurysms on which both endovascular treatment and surgery are suitable. The use of the endovascular treatment for anterior communicating artery aneurysms is expected to increase in the future 1).
With regard to the endovascular technique, firstly, many Anterior communicating artery aneurysm (AcoA aneurysms) have very small sacs, which makes it difficult to distinguish between the aneurysm neck and the microcatheter selection, leading to a few disadvantages.
The standard coil embolization technique is limited by its inability to occlude wide necked aneurysms. Stent deployment across the aneurysm neck supports the coil mass inside the aneurysmal sac, and furthermore, has an effect on local hemodynamic and biologic changes
In the cases of Choi et al., 17 of 112 aneurysms (15%) had very small sacs, and 15 of these patients (88%) were treated with surgical clipping 2).
The second disadvantage of endovascular treatment for AcoA aneurysms is poor controllability and track-ability due to arterial morphology and the acute angle during the endovascular procedure. Moret et al., 3) reported that the main causes of failure to embolize were loops in the cervical and intracranial vessels despite using the cervical approach when necessary and acute angle changes of the posterior projection of the aneurysm 4).
Furthermore, the lumen of the AcoA is relatively small, and remodeling neck techniques using balloons or stents is particularly difficult when treating wide neck or complex aneurysms Safe and complete endovascular occlusion of these aneurysms usually requires the assistance of combined approaches using balloons and stents in an individually tailored strategy 5).
The treatment modality of AcoA aneurysms is affected more by anatomic factors than other aneurysms. However, optimal treatment for AcoA aneurysms cannot be determined by any one anatomic characteristic; rather, all of the morphological features and clinical factors must be considered.
Many papers have emphasized the need for a collaborative approach to treatment strategies and have shown varying tendencies toward coiling or clipping 6)
The decision-making process during recent years has become increasingly more based on collaboration. All patient cases are discussed by a team including at least one endovascular specialist, one neurosurgeon, and one neurologist. Those presenting acutely are always routinely reviewed by both a surgeon and an endovascular radiologist.
In the study of Choi et al., correlated 5 clinical factors and 5 anatomical factors related to determining treatment modality with clinical and anatomical outcomes. Of the 5 clinical factors, age was the important factor in both uni and multivariate analysis. Older patients (age, >65 years) had significantly higher odds of being treated with coil embolization vs. clipping (adjusted OR, 3.78; 95% CI, 1.39-10.3; p=0.0093). The anatomical factors that affected initial treatment modality decision included aneurysm size (small or large vs. medium), neck size (<4 vs. ≥4) dome-to-neck ratio (<2 vs. ≥2), vessel incorporation, multiple lobulation, and morphologic score. Among these 5 anatomical factors, small or large size, dome-to-neck ratio <2, vessel incorporation, and morphologic score ≥2 were statistically significant in univariate analysis. In multivariate analysis, only morphologic score was statistically significant.
Patients with more than 2 unfavorable factors were treated with surgical clipping 4.34 times more often than with coil embolization. Furthermore, higher scoring patients had a higher tendency to be treated with surgical clipping
Balloon remodeling should be considered for broad-based complex ACoA aneurysms. This technique provides a high rate of aneurysm occlusion with an acceptable complication profile, and avoids the need for dual antiplatelet therapy. The balloon trajectory will depend on aneurysm morphology and bilateral access may be useful in selected cases 7).
Intraprocedural aneurysm rupture and thrombus formation are serious complications during coiling of ruptured intracranial aneurysms, and they more often occur in patients with anterior communicating artery aneurysms.
Posterior communicating artery aneurysm recurrence
Seven of eight aneurysms (87.5%) were ruptured. Stent assisted coiling was used in one case that a stent was deployed via PCoA-ipsilateral P2 segment. The dual-microcatheter technique was used in one case. The remaining six cases were treated by coiling alone. One patient (12.5%) suffered perioperative complication, of which a coil herniated into parent vessel during the procedure without symptomatic stroke or other adverse event after the procedure. The initial embolization results showed complete occlusion in five cases and residual neck in three. Six patients (75%) had a mean of 15-month angiographic follow-up and two of them revealed recurrence (33.3%) 1)
Dome size, aneurysm neck width, aneurysm volume, and Pcom diameter were associated with recurrence after coil embolization for IC-PC ANs. In particular, Pcom diameter could be an independent risk factor for recurrence 2)).
Lee et al. from the Chuncheon Army Hospital and St. Mary’s Hospital in Seoul, demonstrated that fetal posterior cerebral artery may be an independent risk factor for the recurrence of posterior communicating artery aneurysms. Therefore, fetal-type posterior cerebral artery can be considered as an important risk factor for posterior communicating artery aneurysm recurrences, along with other known risk factors such as size, ruptured status, endovascular treatment, and incomplete occlusion 3).
In 2010 Golshani et al. from the Division of Vascular and Interventional Radiology, Duke University Medical Center, Durham published that coiled posterior communicating artery aneurysms have a particularly high risk of recurrence and must be followed closely. Posterior communicating artery aneurysms with an elongated fundus, true posterior communicating artery aneurysms, and aneurysms associated with a fetal posterior communicating artery may have better outcome with surgical clipping in terms of completeness of occlusion and preservation of the posterior communicating artery. However, as endovascular technology improves, endovascular treatment of posterior communicating artery aneurysms may become equivalent or preferable in the near future 4).
Unruptured anterior communicating artery aneurysm treatment
The risk associated with treating unruptured anterior communicating artery aneurysms in patients age <65 years is low. Comparing risk with natural history studies, these patients can be expected to outperform natural history within 5 years. Recognizing the risk of smaller anterior communicating artery aneurysms, these findings suggest that treatment of even small lesions may be beneficial 1).
Anterior communicating artery aneurysm treatment requires more collaboration between microsurgical clipping and endovascular therapy. Evaluation of patient and anterior communicating artery aneurysm characteristics by considering the advantages and disadvantages of both techniques could provide an optimal treatment modality. A hybrid vascular neurosurgeon is expected to be a proper solution for the management of these conditions 2).
Anterior Communicating Artery Aneurysm Risk Factors
Age, hypertension, heart disease, diabetes mellitus, cerebral atherosclerosis, aneurysms located at the internal carotid artery (ICA) and aneurysm neck width (N) correlated negatively with rupture risk. Aneurysms located at the anterior communicating artery, bifurcation, irregularity, with a daughter sac, aneurysm height, maximum size, aspect ratio (AR), height-to-width ratio and bottleneck factor were significantly and positively correlated with rupture risk 1).
The anterior communicating artery (AcomA) junction is the most common location for cerebral aneurysms. This might because of increased vascular wall shear stress due to the complex structure of the junction. The aim of a study of İdil Soylu et al. was to investigate the effect of morphological parameters in the development of anterior Communicating Artery Aneurysms. This retrospective study was approved by the institutional ethics committee. A retrospective analysis of the hospital database was performed to identify patients with AcomA aneurysms. Patients with normal computed tomography angiography (CTA) examinations were enrolled in the study as the control group. The control group was similar to the patient group in gender and age. Morphological parameters (vessel diameters, vessel diameter ratios, and vessel angles) on the same side (ipsilateral) and on the opposite side (contralateral) of the patients with aneurysm, and morphological parameters of the control group were compared. A total of 171 subjects were involved in the study (86 patients with aneurysms and 85 patients in the control group). Multivariate regression analysis revealed that the ipsilateral A1-A2 angle (OR: 0.932; 95% CI: 0.903-0.961; p < 0.001), the ipsilateral A1/A2 vessel diameter ratio (OR: 27.725; 95% CI: 1.715-448.139; p = 0.019), and the contralateral internal carotid artery (ICA)/A1 ratio (OR: 11.817; 95% CI: 2.617-53.355; p = 0.001) were significant morphological predictors for developing an aneurysm. An increased contralateral ICA/A1 ratio, an increased ipsilateral A1/A2 vessel diameter ratio, and a narrow bifurcation angle are significant predictors for developing an aneurysm. Therefore, in patients with clinical risk factors these parameters may be interpreted as additional morphological risk factors for developing an aneurysm 2).
In clinic, it’s very common to find out the unequal development of section A1 of anteromedial brain artery. The resulting hemodynamic changes are considered to be one of the main reasons for the formation of anterior communicating artery aneurysms 3).
An asymmetry of the A1 segment of the anterior cerebral artery (A1SA) was identified on digital subtraction angiography studies from 127 patients (21.4%) and was strongly associated with ACoAA (p < 0.0001, OR 13.7). An A1SA independently correlated with the occurrence of ACA infarction in patients with ACoAA (p = 0.047) and in those without an ACoAA (p = 0.015). Among patients undergoing ACoAA coiling, A1SA was independently associated with the severity of ACA infarction (p = 0.023) and unfavorable functional outcome (p = 0.045, OR = 2.4).
An A1SA is a common anatomical variation in SAH patients and is strongly associated with ACoAA. Moreover, the presence of A1SA independently increases the likelihood of ACA infarction. In SAH patients undergoing ACoAA coiling, A1SA carries the risk for severe ACA infarction and thus an unfavorable outcome. Clinical trial registration no.: DRKS00005486 (http://www.drks.de/) 4).
Findings in a study of Matsukawa et al. demonstrated that the anterior projection of an ACoA aneurysm may be related to rupturing. The authors would perhaps recommend treatment to patients with unruptured ACoA aneurysms that have an anterior dome projection, a bleb(s), and a size ≥ 5 mm 5)
Intracranial pseudoaneurysm is a rare complication of endoscopic endonasal surgery. Herein, Morinaga et al., from Fukuoka University Chikushi Hospital describe two-staged stent assisted coil embolization for posterior communicating artery pseudoaneurysm after endoscopic endonasal surgery for pituitary adenoma.
A 68-year-old man had a history of severe adult growth hormone secretion deficiency, requiring growth hormone replacement therapy; secondary adrenal hypofunction; hyperthyroidism; hypertension; constipation; glaucoma; and hyperuricemia. Five years ago, after initial endoscopic transsphenoidal surgery for pituitary adenoma, he was hospitalized for reoperation. Posterior communicating artery injury was observed during second endoscopic trans-sphenoidal surgery and pressure hemostasis was performed using a hemostatic preparation. Immediately post-surgery, a localized subarachnoid hemorrhage was observed. Sudden-onset impaired consciousness and respiratory disturbances ensued on postoperative day 7, and computed tomography of the head was performed. Recurrent subarachnoid hemorrhage was confirmed, and acute hydrocephalus secondary to third ventricular blockage was identified. Cerebral angiography was performed after urgent bilateral cerebral ventricular drainage under general anesthesia. A pseudoaneurysm was identified in the left posterior communicating artery, and coil embolization was performed. Six weeks post-surgery, LVIS® Jr. stent was placed in the posterior communicating artery. Recurrence of the aneurysm was not detected 6 months post-surgery. He underwent lumboperitoneal shunting for secondary normal pressure hydrocephalus after dual antiplatelet therapy discontinuation and is being followed-up as an outpatient with a modified Rankin Scale of 2 10 months post-surgery.
Two-staged stent-assisted coil embolization using LVIS® stent was effective for a posterior communicating artery pseudoaneurysm occurring after posterior communicating artery injury following endoscopic trans-sphenoidal surgery for Follicle stimulating hormone secreting pituitary adenoma 1).
Traumatic injury of the posterior communicating artery or the basilar artery causing arteriovenous fistulae is rare.
Ko et al., report an unusual case of the coincidence of a posterior communicating artery-cavernous sinus fistula and a basilar artery-cavernous sinus fistula associated with traumatic pseudoaneurysms of the posterior communicating and basilar arteries. The fistulas and pseudoaneurysms were obliterated completely after staged endovascular surgery via a transarterial and transvenous route.
This is the first such report worldwide 2).
A middle-aged patient presented with a rapidly growing right dural-based extra-axial posterior clinoid mass extending to the right cavernous sinus that was surgically resected. Histological examination showed solid growth of primitive neuroectodermal tumor arising from the third nerve. Following surgical resection, the patient was further managed by radiation and chemotherapy. Two years later the patient developed new intracranial hemorrhage in the area adjacent to the previous surgical cavity. A cerebral angiogram showed contrast extravasation at the junction of the posterior communicating artery (Pcom) and the right posterior cerebral artery (PCA), with an expanding pseudoaneurysm. This was managed with N-butyl cyanoacrylate embolization. Autopsy showed microscopic recurrence of tumor into the PCA/PCom region with invasion of the wall of the Pcom. This case report illustrates the concept of vascular blowout in intracranial cerebral vasculature. It appears that, in the presence of risk factors that contribute to weakening of vessel walls (surgery, radiation, tumor recurrence), a blowout can occur intracranially 3).