Chronic subdural hematoma recurrence

Chronic subdural hematoma recurrence

In 2 large cohorts of US patients, approximately 5% to 10% of patients who underwent surgery for nontraumatic SDH were required to undergo repeated operation within 30 to 90 days. These results may inform the design of future prospective studies and trials and help practitioners calibrate their index of suspicion to ensure that patients are referred for timely surgical care 1).

Recurrence rates after chronic subdural hematoma (CSDH) evacuation with any of actual techniques twist drill craniostomy (TDC), burr hole craniostomy, craniotomy range from 5% to 30%. 2).

Oslo grading system.

Hyperdense hematoma components were the strongest prognostic factor of recurrence after surgery. Awareness of these findings allows for individual risk assessment and might prompt clinicians to tailor treatment measures 3).


In the series of Santos et al. it was possible to demonstrate an age-related protective factor, analyzed as a continuous variable, regarding the recurrence of the chronic subdural hematoma (CSDH), with a lower rate of recurrence the higher the age.

The results indicate that, among possible factors associated with recurrence, only age presented a protective factor with statistical significance. The fact that no significant difference between the patients submitted to trepanning or craniotomy was found favors the preferential use of burr-hole surgery as a procedure of choice due to its fast and less complex execution 4).


In the series of Han et al. independent risk factors for recurrence were as follows: age > 75 years (HR 1.72, 95% CI 1.03-2.88; p = 0.039), obesity (body mass index ≥ 25.0 kg/m2), and a bilateral operation 5).


Chon et al. shown that postoperative midline shifting (≥5 mm), diabetes mellitus, preoperative seizure, preoperative width of hematoma (≥20 mm), and anticoagulant therapy were independent predictors of the recurrence of chronic subdural hematoma.

According to internal architecture of hematoma, the rate of recurrence was significantly lower in the homogeneous and the trabecular type than the laminar and separated type 6).


The recurrence rate of chronic subdural hematoma cSDH seems to be related to the excessive neoangiogenesis in the parietal membrane, which is mediated via vascular endothelial growth factor (VEGF). This is found to be elevated in the hematoma fluid and is dependent on eicosanoid/prostaglandin and thromboxane synthesis via cyclooxygenase-2 (COX-2).

see Chronic subdural hematoma and anticoagulant therapy.

Antiplatelet therapy significantly influences the recurrence of CSDH 7).

Timing of Low-Dose Aspirin Discontinuation for chronic subdural hematoma.

Pneumocephalus

Remaining pneumocephalus is seen as an approved factor of recurrence 8) 9).

Septation

Jack et al.found a 12% reoperation rate. CSDH septation (seen on computed tomogram scan) was found to be an independent risk factor for recurrence requiring reoperation (p=0.04). Larger post-operative subdural haematoma volume was also significantly associated with requiring a second drainage procedure (p<0.001). Independent risk factors of larger post-operative haematoma volume included septations within a CSDH (p<0.01), increased pre-operative haematoma volume (p<0.01), and a greater amount of parenchymal atrophy (p=0.04). A simple scoring system for quantifying recurrence risk was created and validated based on patient age (< or ≥80 years), haematoma volume (< or ≥160cc), and presence of septations within the subdural collection (yes or no).

Septations within CSDHs are associated with larger post-operative residual haematoma collections requiring repeat drainage. When septations are clearly visible within a CSDH, craniotomy might be more suitable as a primary procedure as it allows greater access to a septated subdural collection. The proposed scoring system combining haematoma volume, age, and presence of septations might be useful in identifying patients at higher risk for recurrence 10).

Membranectomy

Opening the internal hematoma membrane does not alter the rate of patients requiring revision surgery and the number of patients showing a marked residual hematoma six weeks after evacuation of a CSDH 11).

In the study of Lee et al, an extended surgical approach with partial membranectomy has no advantages regarding the rate of reoperation and the outcome. As initial treatment, burr-hole drainage with irrigation of the hematoma cavity and closed-system drainage is recommended. Extended craniotomy with membranectomy is now reserved for instances of acute rebleeding with solid hematoma 12).

Diabetes

Surgeons should consider informing patients with diabetes mellitus that this comorbidity is associated with an increased likelihood of recurrence

13) 14) 15).


Balser et al. report 11% recurrence, which included individuals who recurred as late as 3 years after initial diagnosis 16).

Close imaging follow-up is important for CSDH patients for recurrence prediction. Using quantitative CT volumetric analysis, strong evidence was provided that changes in the residual fluid volume during the ‘self-resolution’ period can be used as significantly radiological predictors of recurrence 17).

A structural equation model showed a significant association between increased antiinflammatory activity in hematoma fluid samples and a lower risk of recurrence, but this relationship was not statistically significant in venous blood samples. Moreover, these findings indicate that anti-inflammatory activities in the hematoma may play a role in the risk of a recurrence of CSDH 18).

Irrigation with artificial cerebrospinal fluid (ACF) decreased the rate of CSDH recurrence 19).

There is no definite operative procedure for patients with intractable chronic subdural hematoma (CSDH).

Most recurrent hematomas are managed successfully with burr hole craniostomies with postoperative closed-system drainage. Refractory hematomas may be managed with a variety of techniques, including craniotomy or subdural-peritoneal shunt placement 20).

Although many studies have reported risk factors or treatments in efforts to prevent recurrence, those have focused on single recurrence, and little cumulative data is available to analyze refractory CSDH.

Matsumoto et al. defined refractory CSDH as ≥2 recurrences, then analyzed and compared clinical factors between patients with single recurrence and those with refractory CSDH in a cohort study, to clarify whether patients with refractory CSDH experience different or more risk factors than patients with single recurrence, and whether burr-hole irrigation with closed-system drainage reduces refractory CSDH.

Seventy-five patients had at least one recurrence, with single recurrence in 62 patients and ≥2 recurrences in 13 patients. In comparing clinical characteristics, patients with refractory CSDH were significantly younger (P=0.04) and showed shorter interval to first recurrence (P<0.001). Organized CSDH was also significantly associated with refractory CSDH (P=0.02). Multivariate logistic regression analysis identified first recurrence interval <1 month (OR 6.66, P<0.001) and age <71 years (OR 4.16, P<0.001) as independent risk factors for refractory CSDH. On the other hand, burr-hole irrigation with closed-system drainage did not reduce refractory CSDH.

When patients with risk factors for refractory CSDH experience recurrence, alternative surgical procedures may be considered as the second surgery, because burr-hole irrigation with closed-system drainage did not reduce refractory CSDH 21).

Implantation of a reservoir 22) 23) 24).

Subdural-peritoneal shunt 25).

Embolization of the MMA is effective for refractory CSDH or CSDH patients with a risk of recurrence, and is considered an effective therapeutic method to stop hematoma enlargement and promote resolution 26) 27) 28) 29) 30) 31).

A pilot study indicated that perioperative middle meningeal artery (MMA) embolization could be offered as the least invasive and most effectual means of treatment for resistant patients of CSDHs with 1 or more recurrences 32).

Chihara et al. have treated three cases of CSDH with MMA embolization to date, but there was a postoperative recurrence in one patient, which required a craniotomy for hematoma removal and capsulectomy. MMA embolization blocks the blood supply from the dura to the hematoma outer membrane in order to prevent recurrences of refractory CSDH. Histopathologic examination of the outer membrane of the hematoma excised during craniotomy showed foreign-body giant cells and neovascular proliferation associated with embolization. Because part of the hematoma was organized in this case, the CSDH did not resolve when the MMA was occluded, and the development of new collateral pathways in the hematoma outer membrane probably contributed to the recurrence. Therefore, in CSDH with some organized hematoma, MMA embolization may not be effective. Magnetic resonance imaging (MRI) should be performed in these patients before embolization 33).

see Chronic subdural hematoma recurrence case series.

Chronic subdural hematoma recurrence case reports.


1)

Knopman J, Link TW, Navi BB, Murthy SB, Merkler AE, Kamel H. Rates of Repeated Operation for Isolated Subdural Hematoma Among Older Adults. JAMA Netw Open. 2018 Oct 5;1(6):e183737. doi: 10.1001/jamanetworkopen.2018.3737. PubMed PMID: 30646255.
2)

Escosa Baé M, Wessling H, Salca HC, de Las Heras Echeverría P. Use of twist-drill craniostomy with drain in evacuation of chronic subdural hematomas: independent predictors of recurrence. Acta Neurochir (Wien). 2011 May;153(5):1097-103. doi: 10.1007/s00701-010-0903-3. Epub 2010 Dec 31. PubMed PMID: 21193935.
3)

Miah IP, Tank Y, Rosendaal FR, Peul WC, Dammers R, Lingsma HF, den Hertog HM, Jellema K, van der Gaag NA; Dutch Chronic Subdural Hematoma Research Group. Radiological prognostic factors of chronic subdural hematoma recurrence: a systematic review and meta-analysis. Neuroradiology. 2020 Oct 22. doi: 10.1007/s00234-020-02558-x. Epub ahead of print. Erratum in: Neuroradiology. 2020 Nov 5;: PMID: 33094383.
4)

Santos RGD, Xander PAW, Rodrigues LHDS, Costa GHFD, Veiga JCE, Aguiar GB. Analysis of predisposing factors for chronic subdural hematoma recurrence. Rev Assoc Med Bras (1992). 2019 Jul 22;65(6):834-838. doi: 10.1590/1806-9282.65.6.834. PubMed PMID: 31340313.
5)

Han MH, Ryu JI, Kim CH, Kim JM, Cheong JH, Yi HJ. Predictive factors for recurrence and clinical outcomes in patients with chronic subdural hematoma. J Neurosurg. 2017 Nov;127(5):1117-1125. doi: 10.3171/2016.8.JNS16867. Epub 2016 Dec 16. PubMed PMID: 27982768.
6)

Chon KH, Lee JM, Koh EJ, Choi HY. Independent predictors for recurrence of chronic subdural hematoma. Acta Neurochir (Wien). 2012 Sep;154(9):1541-8. doi: 10.1007/s00701-012-1399-9. Epub 2012 Jun 1. PubMed PMID: 22653496.
7)

Wada M, Yamakami I, Higuchi Y, Tanaka M, Suda S, Ono J, Saeki N. Influence of antiplatelet therapy on postoperative recurrence of chronic subdural hematoma: a multicenter retrospective study in 719 patients. Clin Neurol Neurosurg. 2014 May;120:49-54. doi: 10.1016/j.clineuro.2014.02.007. Epub 2014 Feb 24. PubMed PMID: 24731576.
8)

Mori K, Maeda M (2001) Surgical treatment of chronic subdural hematoma in 500 consecutive cases: clinical characteristics, surgical outcome, complications, and recurrence rate. Neurol Med Chir (Tokyo) 41:371–381
9)

Stanišić M, Hald J, Rasmussen IA, Pripp AH, Ivanović J, Kolstad F, Sundseth J, Züchner M, Lindegaard KF (2013) Volume and densities of chronic subdural haematoma obtained from CT imaging as predictors of postoperative recurrence: a prospective study of 107 operated patients. Acta Neurochir 155:323–333
10)

Jack A, O’Kelly C, McDougall C, Max Findlay J. Predicting Recurrence after Chronic Subdural Haematoma Drainage. Can J Neurol Sci. 2015 Jan 5:1-6. [Epub ahead of print] PubMed PMID: 25557536.
11)

Unterhofer C, Freyschlag CF, Thomé C, Ortler M. Opening the Internal Hematoma Membrane does not Alter the Recurrence Rate of Chronic Subdural Hematomas – A Prospective Randomized Trial. World Neurosurg. 2016 May 2. pii: S1878-8750(16)30210-8. doi: 10.1016/j.wneu.2016.04.081. [Epub ahead of print] PubMed PMID: 27150644.
12)

Lee JY, Ebel H, Ernestus RI, Klug N. Various surgical treatments of chronic subdural hematoma and outcome in 172 patients: is membranectomy necessary? Surg Neurol. 2004 Jun;61(6):523-7; discussion 527-8. PubMed PMID: 15165784.
13)

Matsumoto K, Akagi K, Abekura M, Ryujin H, Ohkawa M, Iwasa N, Akiyama C. Recurrence factors for chronic subdural hematomas after burr-hole craniostomy and closed system drainage. Neurol Res. 1999 Apr;21(3):277-80. PubMed PMID: 10319336.
14)

Yamamoto H, Hirashima Y, Hamada H, Hayashi N, Origasa H, Endo S. Independent predictors of recurrence of chronic subdural hematoma: results of multivariate analysis performed using a logistic regression model. J Neurosurg. 2003 Jun;98(6):1217-21. PubMed PMID: 12816267.
15)

Pang CH, Lee SE, Kim CH, Kim JE, Kang HS, Park CK, Paek SH, Kim CH, Jahng TA, Kim JW, Kim YH, Kim DG, Chung CK, Jung HW, Yoo H. Acute intracranial bleeding and recurrence after bur hole craniostomy for chronic subdural hematoma. J Neurosurg. 2015 Jul;123(1):65-74. doi: 10.3171/2014.12.JNS141189. Epub 2015 Feb 13. PubMed PMID: 25679282.
16)

Balser D, Rodgers SD, Johnson B, Shi C, Tabak E, Samadani U. Evolving management of symptomatic chronic subdural hematoma: experience of a single institution and review of the literature. Neurol Res. 2013 Apr;35(3):233-42. doi: 10.1179/1743132813Y.0000000166. Review. PubMed PMID: 23485050.
17)

Xu FF, Chen JH, Leung GK, Hao SY, Xu L, Hou ZG, Mao X, Shi GZ, Li JS, Liu BY. Quantitative computer tomography analysis of post-operative subdural fluid volume predicts recurrence of chronic subdural haematoma. Brain Inj. 2014;28(8):1121-6. doi: 10.3109/02699052.2014.910702. Epub 2014 May 6. PubMed PMID: 24801643.
18)

Pripp AH, Stanišić M. The Correlation between Pro- and Anti-Inflammatory Cytokines in Chronic Subdural Hematoma Patients Assessed with Factor Analysis. PLoS One. 2014 Feb 27;9(2):e90149. doi: 10.1371/journal.pone.0090149. eCollection 2014. PubMed PMID: 24587250.
19)

Adachi A, Higuchi Y, Fujikawa A, Machida T, Sueyoshi S, Harigaya K, Ono J, Saeki N. Risk factors in chronic subdural hematoma: comparison of irrigation with artificial cerebrospinal fluid and normal saline in a cohort analysis. PLoS One. 2014 Aug 4;9(8):e103703. doi: 10.1371/journal.pone.0103703. eCollection 2014. PubMed PMID: 25089621; PubMed Central PMCID: PMC4121178.
20)

Desai VR, Scranton RA, Britz GW. Management of Recurrent Subdural Hematomas. Neurosurg Clin N Am. 2017 Apr;28(2):279-286. doi: 10.1016/j.nec.2016.11.010. Epub 2017 Jan 4. Review. PubMed PMID: 28325462.
21)

Matsumoto H, Hanayama H, Okada T, Sakurai Y, Minami H, Masuda A, Tominaga S, Miyaji K, Yamaura I, Yoshida Y, Yoshida K. Clinical investigation of refractory chronic subdural hematoma: a comparison of clinical factors between single and repeated recurrences. World Neurosurg. 2017 Aug 24. pii: S1878-8750(17)31402-X. doi: 10.1016/j.wneu.2017.08.101. [Epub ahead of print] PubMed PMID: 28844917.
22)

Sato M, Iwatsuki K, Akiyama C, Masana Y, Yoshimine T, Hayakawa T. [Use of Ommaya CSF reservoir for refractory chronic subdural hematoma]. No Shinkei Geka. 1999 Apr;27(4):323-8. Japanese. PubMed PMID: 10347846.
23)

Sato M, Iwatsuki K, Akiyama C, Kumura E, Yoshimine T. Implantation of a reservoir for refractory chronic subdural hematoma. Neurosurgery. 2001 Jun;48(6):1297-301. PubMed PMID: 11383733.
24)

Laumer R. Implantation of a reservoir for refractory chronic subdural hematoma. Neurosurgery. 2002 Mar;50(3):672. PubMed PMID: 11841742.
25)

Misra M, Salazar JL, Bloom DM. Subdural-peritoneal shunt: treatment for bilateral chronic subdural hematoma. Surg Neurol. 1996 Oct;46(4):378-83. PubMed PMID: 8876720.
26)

Mandai S, Sakurai M, Matsumoto Y. Middle meningeal artery embolization for refractory chronic subdural hematoma. Case report. J Neurosurg. 2000 Oct;93(4):686-8. PubMed PMID: 11014549.
27)

Takahashi K, Muraoka K, Sugiura T, Maeda Y, Mandai S, Gohda Y, Kawauchi M, Matsumoto Y. [Middle meningeal artery embolization for refractory chronic subdural hematoma: 3 case reports]. No Shinkei Geka. 2002 May;30(5):535-9. Japanese. PubMed PMID: 11993178.
28)

Hirai S, Ono J, Odaki M, Serizawa T, Nagano O. Embolization of the Middle Meningeal Artery for Refractory Chronic Subdural Haematoma. Usefulness for Patients under Anticoagulant Therapy. Interv Neuroradiol. 2004 Dec 24;10 Suppl 2:101-4. Epub 2008 May 15. PubMed PMID: 20587257; PubMed Central PMCID: PMC3522210.
29)

Tsukamoto Y, Oishi M, Shinbo J, Fujii Y. Transarterial embolisation for refractory bilateral chronic subdural hematomas in a case with dentatorubral-pallidoluysian atrophy. Acta Neurochir (Wien). 2011 May;153(5):1145-7. doi: 10.1007/s00701-010-0891-3. Epub 2010 Dec 2. PubMed PMID: 21125409.
30)

Mino M, Nishimura S, Hori E, Kohama M, Yonezawa S, Midorikawa H, Kaimori M, Tanaka T, Nishijima M. Efficacy of middle meningeal artery embolization in the treatment of refractory chronic subdural hematoma. Surg Neurol Int. 2010 Dec 13;1:78. doi: 10.4103/2152-7806.73801. PubMed PMID: 21206540; PubMed Central PMCID: PMC3011107.
31)

Hashimoto T, Ohashi T, Watanabe D, Koyama S, Namatame H, Izawa H, Haraoka R, Okada H, Ichimasu N, Akimoto J, Haraoka J. Usefulness of embolization of the middle meningeal artery for refractory chronic subdural hematomas. Surg Neurol Int. 2013 Aug 19;4:104. doi: 10.4103/2152-7806.116679. eCollection 2013. PubMed PMID: 24032079; PubMed Central PMCID: PMC3766342.
32)

Kim E. Embolization Therapy for Refractory Hemorrhage in Patients with Chronic Subdural Hematomas. World Neurosurg. 2017 May;101:520-527. doi: 10.1016/j.wneu.2017.02.070. Epub 2017 Feb 27. PubMed PMID: 28249828.
33)

Chihara H, Imamura H, Ogura T, Adachi H, Imai Y, Sakai N. Recurrence of a Refractory Chronic Subdural Hematoma after Middle Meningeal Artery Embolization That Required Craniotomy. NMC Case Rep J. 2014 May 9;1(1):1-5. doi: 10.2176/nmccrj.2013-0343. eCollection 2014 Oct. PubMed PMID: 28663942; PubMed Central PMCID: PMC5364934.

Ventriculoperitoneal shunt abdominal complications

Ventriculoperitoneal shunt abdominal complications

Abdominal complications include peritonitisascites, bowel and abdominal wall perforation, and inguinal hernias.

Abdominal complications are reported in 5–47 % of ventriculoperitoneal shunt cases 1) 2).

Ascites

Abdominal pseudocyst

Bowel perforation

Hydrocele

Shunt extrusion

Shunt migration

CSF leaks

Viscous perforations

Protrusion of the catheter from the anus

Spontaneous knotting of the peritoneal catheter is a rare complication of the VP shunt 3).

Peritoneal catheter knot formation

Liver abscess

Pyogenic liver abscess in Taiwan is most commonly due to Klebsiella pneumoniae infection in diabetic patients, and less frequently due to biliary tract infections. Liver abscess caused by ventriculoperitoneal (VP) shunt is very rare. We report a case of liver abscess caused by methicillin-resistant Staphylococcus aureus (MRSA), which developed as a complication of an infected VP shunt. A 53-year-old woman, who had shad a VP shunt implanted 3 months previously for hydrocephalus due to intracranial hemorrhage, presented with fever off and on, drowsiness and seizure attacks for 1 week. Computed tomography (CT) of the brain showed only mild right-sided hydrocephalus, and was negative for intracranial hemorrhage and intracranial mass. Analysis of cerebrospinal fluid showed significant pleocytosis and hypoglycorrhachia. CT scan of the abdomen disclosed a huge abscess in the right lobe of the liver. Cultures of both the cerebrospinal fluid and aspirated liver abscess isolated MRSA. The patient was treated with intraventricular and intravenous vancomycin, intravenous teicoplanin and oral rifampicin, followed by oral chloramphenicol and rifampicin. Percutaneous drainage of the liver abscess and externalization of the VP shunt were performed. The liver abscess had resolved almost completely on ultrasonography after 2 weeks of therapy. Liver abscess in patients with a VP shunt should be considered a possible abdominal complication of the VP shunt, and may be caused by unusual pathogens. Diagnosis requires CT scan and direct aspiration and culture of the liver abscess. Treatment requires management of both the liver abscess and the infected shunt 4).

Liver pseudocyst

The formation of a liver pseudocyst is a rare occurrence, and its mechanisms are still largely unknown.

Mallereau et al. reported the case of a 69-year-old woman with a ventriculoperitoneal shunt, inserted for the management of hydrocephalus after aneurysmal subarachnoid hemorrhage, presenting to the Accident and Emergency for acute cholecystitis. Besides confirming the diagnosis, an ultrasound investigation revealed the presence of a hepatic cyst. Conservative treatment with antibiotics and non-steroidal anti-inflammatory drugs was performed with favorable outcomes and resorption of the cyst. Interestingly the patient kept on presenting several similar episodes managed well by non-steroidal anti-inflammatory drugs alone, each of them associated with transient symptoms and signs of ventriculoperitoneal shunt malfunction. Computerized Tomography brain and lumbar puncture were normal, whereas the CT abdomen showed the ventriculoperitoneal shunt distal catheter passing through the hepatic cyst. Given the ventriculoperitoneal shunt malfunction, in the context of an infective/inflammatory process, a conversion of the ventriculoperitoneal shunt into a ventriculoatrial shunt was carried out with a successful clinical outcome.

Based on current literature they propose a clinical and radiological classification of such pseudocysts related to ventriculoperitoneal shunt. Clinical presentation, diagnostic findings, and management options are proposed for each type: purely infective, spurious (infective/inflammatory), and purely inflammatory. In the absence of system infection, a simple replacement of the distal catheter seems to be the best solution 5).

References

1)

Chung J, Yu J, Joo HK, Se JN, Kim M. Intraabdominal complications secondary to ventriculoperitoneal shunts: CT findings and review of the literature. American Journal of Roentgenology. 2009;193(5):1311–1317.
2)

Murtagh FR, Quencer RM, Poole CA. Extracranial complications of cerebrospinal fluid shunt function in childhood hydrocephalus. American Journal of Roentgenology. 1980;135(4):763–766.
3)

Borcek AO, Civi S, Golen M, Emmez H, Baykaner MK. An unusual ventriculoperitoneal shunt complication: spontaneous knot formation. Turkish Neurosurgery. 2012;22(2):261–264.
4)

Shen MC, Lee SS, Chen YS, Yen MY, Liu YC. Liver abscess caused by an infected ventriculoperitoneal shunt. J Formos Med Assoc. 2003 Feb;102(2):113-6. PubMed PMID: 12709741.
5)

Mallereau CH, Ganau M, Todeschi J, Addeo PF, Moliere S, Chibbaro S. Relapsing-Remitting Hepatic Pseudo-Cyst: a great simulator of malfunctioning ventriculoperitoneal shunt. Case report and proposal of a new classification. Neurochirurgie. 2020 Oct 10:S0028-3770(20)30399-4. doi: 10.1016/j.neuchi.2020.08.001. Epub ahead of print. PMID: 33049283.

Intraoperative microelectrode recording

Intraoperative microelectrode recording

Microelectrode recording (MER) is used to confirm targeting accuracy during deep brain stimulation (DBS) surgery.


While the efficacy of deep brain stimulation (DBS) to treat various neurological disorders is undisputed, the surgical methods differ widely and the importance of intraoperative microelectrode recording (MER) or macrostimulation (MS) remains controversially debated 1).


At many centers around the world that treat movement disorders, the gold standard for optimally targeting the sensorimotor area of the STN currently relies on microelectrode recording (MER) of single and multi-neuron activity traversing the planned surgical trajectories.

see HaGuide Tool.

When extracellular microelectrodes (tens of microns in diameter) are placed within the brain, they record the extracellular electric field generated by multiple nearby spiking neurons. This is the basis of the microelectrode recording technique used daily by many functional neurosurgeons, and is core to the development of various brain computer interfaces.


The functional regions clustering through microelectrode recording (MER) is a critical step in deep brain stimulation (DBS) surgery. The localization of the optimal target highly relies on the neurosurgeon’s empirical assessment of the neurophysiological signal. This work presents an unsupervised clustering algorithm to get the optimal cluster result of the functional regions along the electrode trajectory.

The dataset consists of the MERs obtained from the routine bilateral DBS for PD patients. Several features have been extracted from MER and divided into groups based on the type of neurophysiological signal. We selected single feature groups rather than all features as the input samples of each division of the divisive hierarchical clustering (DHC) algorithm. And the optimal cluster result has been achieved through a feature group combination selection (FGS) method based on genetic algorithm (GA). To measure the performance of this method, we compared the accuracy and validation indexes of three methods, including DHC only, DHC with GA-based FGS and DHC with GA-based feature selection (FS) in other studies, on the universal and DBS datasets.

Results show that the DHC with GA-based FGS achieved the optimal cluster result compared with other methods. The three borders of the STN can be identified from the cluster result. The dorsoventral sizes of the STN and dorsal STN are 4.45 mm and 2.02 mm. In addition, the features extracted from the multiunit activity, background unit activity and local field potential are found to be the most representative feature groups to identify the dorsal, d-v and ventral borders of the STN, respectively.

The clustering algorithm showed a reliable performance of the automatic identification of functional regions in DBS. The findings can provide valuable assistance for both neurosurgeons and stereotactic surgical robots in DBS surgery 2).


It is unclear which magnetic resonance imaging (MRI) sequence most accurately corresponds with the electrophysiological subthalamic nucleus (STN) obtained during microelectrode recording (MER, MER-STN). CT/MRI fusion allows for comparison between MER-STN and the STN visualized on preoperative MRI (MRI-STN).

Kochanski et al. describe a technique using intraoperative computed tomography (CT) extrapolation (iCTE) to predetermine and adjust the trajectory of the guide tube to improve microelectrode targeting accuracy. They hypothesized that this technique would decrease the number of MER tracks and operative time, while increasing the recorded length of the subthalamic nucleus (STN) 3).

Case series

Krauss et al. included 101 patients who underwent awake bilateral implantation of electrodes in the subthalamic nucleus with microelectrode recording (MER) and macrostimulation (MS) for Parkinson’s disease from 2009 to 2017 in a retrospective observational study. They analyzed intraoperative motor outcomes between anatomically planned stimulation point (PSP) and definite stimulation point (DSP), lead adjustments, and Unified Parkinson’s Disease Rating Scale Item III (UPDRS-III), levodopa equivalent daily dose (LEDD), and adverse events (AE) after 6 months.

They adjusted 65/202 leads in 47/101 patients. In adjusted leads, MS results improved significantly when comparing PSP and DSP (p < 0.001), resulting in a number needed to treat of 9.6. After DBS, UPDRS-III and LEDD improved significantly after 6 months in adjusted and nonadjusted patients (p < 0.001). In 87% of leads, the active contact at 6 months still covered the optimal stimulation point during surgery. In total, 15 AE occurred.

MER and MS have a relevant impact on the intraoperative decision of final lead placement and prevent a substantial rate of poor stimulation outcome. The optimal stimulation points during surgery and chronic stimulation strongly overlap. Follow-up UPDRS-III results, LEDD reductions, and DBS-related AE correspond well to previously published data 4).


The precision and accuracy of direct targeting with quantitative susceptibility mapping (QSM) was examined in a total of 25 Parkinson’s disease patients between 2013 and 2015 at the Department of Neurosurgery, Mount Sinai Health System, New York. QSM was utilized as the primary magnetic resonance imaging (MRI) method to perform direct STN targeting on a stereotactic planning station utilizing computed tomography/MR fusion. Intraoperative microelectrode recordings (MER) were obtained to confirm appropriate trajectory through the sensorimotor STN.

Estimations of STN thickness between the MER and QSM methods appeared to be correlated. Mean STN thickness was 5.3 mm. Kinesthetic responsive cells were found in > 90% of electrode runs. The mean radial error (±SEM) was 0.54 ± 0.1 mm. Satisfactory clinical response as determined by Unified Parkinson’s Disease Rating Scale (UPDRS III) was seen at 12 mo after surgery.

Direct targeting of the sensorimotor STN using QSM demonstrates MER correlation and can be safely used for deep brain stimulation lead placement with satisfactory clinical response. These results imply that targeting based on QSM signaling alone is sufficient to obtain reliable and reproducible outcomes in the absence of physiological recordings 5).

In their analysis, Rasouli et al accept that the raw measurements they derived by the 2 methods (microelectrode recording [MER] vs quantitaive susceptibility mapping [QSM]) do not exhibit a high degree of correlation. They offer several reasons for this (differences in resolution, standard deviations, and narrow range of measurements), thereby justifying the use of normalized data and the Bland–Altman analysis. In contrast to the Bland–Altman analysis, which suggests agreement, the intra-correlation coefficient (ICC) = 0.12 implies that there is high variability between QSM and MER measurements within an individual (ie, they are not in good agreement). More useful in our view would be to see how well the actual measurements made with the 2 methods agree on a case by case basis. How often do the measurements agree within 0.1, 0.5, 1, 2 mm, etc.? Such valuable information would allow the readers to decide for themselves whether a measured subthalamic nucleus (STN) span on QSM is a legitimate proxy for the gold standard of measuring the STN with MER and we urge the authors to publish this data in a subsequent letter 6).

References

1) , 4)

Krauss P, Oertel MF, Baumann-Vogel H, Imbach L, Baumann CR, Sarnthein J, Regli L, Stieglitz LH. Intraoperative Neurophysiologic Assessment in Deep Brain Stimulation Surgery and its Impact on Lead Placement. J Neurol Surg A Cent Eur Neurosurg. 2020 Oct 13. doi: 10.1055/s-0040-1716329. Epub ahead of print. PMID: 33049794.
2)

Cao L, Jie L, Zhou Y, Liu Y, Liu H. Automatic feature group combination selection method based on GA for the functional regions clustering in DBS. Comput Methods Programs Biomed. 2019 Sep 23;183:105091. doi: 10.1016/j.cmpb.2019.105091. [Epub ahead of print] PubMed PMID: 31590098.
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