Anterior clinoidectomy

Anterior clinoidectomy

The optic nerve within the optic canal, the parophthalmic segment of the internal carotid artery, and the oculomotor nerve in the superior orbital fissure all lay against the anterior clinoid process. Bone resection uncovers these structures.


Removal of the anterior clinoid process(ACP) facilitates radical removal of tumors or radical neck clipping of aneurysms in the suprasellar region and parasellar regions by providing a wide operative exposure of the internal carotid artery (ICA) and the optic nerve and by reducing the need for brain retraction.

Preoperative imaging of anterior clinoid region meningioma can accurately predict the presence or absence of tumor involvement of the clinoid in only approximately 75% of cases. In light of the fact that a quarter of patients with radiographically negative clinoids will have tumor present on pathological analysis, Copeland et al. recommend a clinoidectomy for all anterior clinoid region meningioma1).

Initially developed intradurally 2) 3) , later extradural 4).


A high-speed power-drilling technique of anterior clinoidectomy has been advocated in all publications on paraclinoid region surgery. The entire shaft of the power drill is exposed in the operative field; thus, all neurovascular structures in proximity to any portion of the full length of the rotating drill bit are at risk for direct mechanical and/or thermal injury. Ultrasonic bone removal has recently been developed to mitigate the potential complications of the traditional power-drilling technique of anterior clinoidectomy. However, ultrasound-related cranial neuropathies are recognized complications of its use, as well as the increased cost of device acquisition and maintenance.

see Endoscopic extradural anterior clinoidectomy.

Extradural clinoidectomy

Extradural removal of the anterior clinoid process (ACP) is a crucial step in the proper surgical exposure of various pathologies in and around the central skull base. Since the pioneering description by Vinko Dolenc, the technique of extradural clinoidectomy has undergone several refinements in the light of improved understanding of microsurgical anatomy and maturation of neurosurgical techniques 5).

Noguchi et al., in 2005 compared the original Dolenc procedure and its subsequent derivatives with their own simpler and less laborious technique. Different clinical situations in which to use the procedure were described based on the authors’ experience from 60 cases (40 aneurysm cases and 20 tumor cases) during a 4-year period 6).

For extradural resection of the anterior clinoid process and surrounding bone, two key steps are recommended: bony opening of the superior orbital fissure, and transection of the orbitotemporal periosteal fold.

Key Points: Pterional craniotomy • Complete extradural anterior clinoidectomy • Slit dura (3 mm) to drain cerebrospinal fluid • Peel dura from orbital roof and lateral wall • Bony opening of superior orbital fissure to use it as surgical corridor • Drilling of optic canal • Transection of orbitotemporal periosteal fold • Hollow anterior clinoid process and piece-meal resection • Transection of falciforme ligament to free optic nerve • Replace falciforme ligament by extradural free pericranial flap 7).

Hybrid technique

It is important to note that the surgeon should prefer the method he or she feels most comfortable with. This preference is often affected by the surgeon’s training. Extradural clinoidectomy is advantageous during removal of the medial sphenoid wing meningiomas as aggressive bony removal facilitates extradural devascularization of the tumor and may enhance gross tumor removal, especially if the clinoid is infiltrated with tumor. The intradural technique may be preferred for clipping of ophthalmic aneurysms as bony removal can be tailored based on the pathology at hand and clinoidectomy can be done under careful monitoring of the aneurysm to prevent manipulations that would place the aneurysm at risk of intraoperative rupture.

The hybrid method theoretically can be used as a versatile method under both circumstances mentioned above. Cutting the dura along the sphenoid wing will prevent the dural layers from obscuring the clinoid and offers intradural visualization to monitor the lesion and potentially tailor bony removal. 8).

In a study, Tayebi Meybodi et al., sought to develop a hybrid technique based on localization of the optic strut (OS) to combine the advantages and avoid the disadvantages of both techniques. Ten cadaveric specimens were prepared for surgical simulation. After a standard pterional craniotomy, the anterior clinoid process (ACP) was resected in 2 steps. The segment anterior to the OS was resected extradurally, while the segment posterior to the OS was resected intradurally. The proposed technique was performed in 6 clinical cases to evaluate its safety and efficiency. Anterior clinoidectomy was successfully performed in all cadaveric specimens and all 6 patients by using the proposed technique. The extradural phase enabled early decompression of the optic nerve while avoiding the adjacent internal carotid artery. The OS was drilled intradurally under direct visualization of the adjacent neurovascular structures. The described landmarks were easily identifiable and applicable in the surgically treated patients. No operative complication was encountered. A proposed 2-step hybrid technique combines the advantages of the extradural and intradural techniques while avoiding their disadvantages. This technique allows reduced intradural drilling and subarachnoid bone dust deposition. Moreover, the most critical part of the clinoidectomy-that is, drilling of the OS and removal of the body of the ACP-is left for the intradural phase, when critical neurovascular structures can be directly viewed 9).


Extradural anterior clinoidectomy is a versatile technique to increase exposure of the sellar and parasellar region. It is of particular use in the resection of clinoidal meningiomas, as sphenoidal and clinoidal hyperostosis can cause compression of the optic nerve. Extradural clinoidectomy follows a series of steps, consisting of (1) unroofing of the superior orbital fissure, (2) unroofing of the optic canal, (3) removal of the optic strut, and (4) removal of the anterior clinoid process. The authors show these steps in detail, as well as their application to the resection of a large clinoidal meningioma. The video can be found here: 10).

Case series


Between June 2007 and January 2011, a total of 82 patients with neoplastic and vascular lesions underwent anterior clinoidectomy by the senior author (J.H.) through the LSO approach. They analyzed the operative videos paying particular attention to the surgical technique used for removal of the anterior clinoid process (ACP) and compared the microsurgical nuances to postoperative complications related to anterior clinoidectomy.

Forty-five patients were treated for aneurysms; 35 patients for intraorbital, parasellar, and suprasellar tumors; and 2 patients for carotid-cavernous fistulas. Intradural anterior clinoidectomy was performed in 67 (82%) cases; in 15 (18%) cases an extradural approach was used. In 51 (62%) cases, ACP was removed completely, whereas in the remaining 31 (38%) a tailored anterior clinoidectomy was performed. Four (5%) patients had new postoperative visual deficits and 3 (4%) experienced a worsening of preoperative visual deficits. Twelve (15%) patients improved their preoperative visual deficits after intradural anterior clinoidectomy. Ultrasonic bone device is a useful tool but may damage the optic nerve when performing anterior clinoidectomy. There was no mortality in our series.

Anterior clinoidectomy can be performed through an LSO approach with a safety profile that is comparable to other approaches. Ultrasonic bone dissector is a useful tool but may lead to injury of the optic nerve and should be used very carefully in its vicinity 11).


A retrospective review of a cerebrovascular/cranial base fellowship-trained neurosurgeon’s 45 consecutive cases of anterior clinoidectomy using the “no-drill” technique is presented. Clinical indications have been primarily small to giant aneurysms of the proximal internal carotid artery; however, in addition to ophthalmic segment aneurysms, selected internal carotid artery-posterior communicating artery aneurysms and internal carotid artery bifurcation aneurysms, and other large/giant/complex anterior circulation aneurysms, this surgical series of “no-drill” anterior clinoidectomy includes tuberculum sellae meningiomas, clinoidal meningiomas, cavernous sinus lesions, pituitary macroadenomas with significant suprasellar extension, other perichiasmal lesions (sarcoid), and fibrous dysplasia. A bony opening is made in the mid-to posterior orbital roof after the initial pterional craniotomy. Periorbita is dissected off the bone from inside the orbital compartment. Subsequent piecemeal resection of the medial sphenoid wing, anterior clinoid process, optic canal roof, and optic strut is performed with bone rongeurs of various sizes via the bony window made in the orbital roof. RESULTS: No power drilling was used in this surgical series of anterior clinoidectomies. Optimal microsurgical exposure was obtained in all cases to facilitate complete aneurysm clippings and lesionectomies. There were no cases of direct injury to surrounding neurovascular structures from the use of the “no-drill” technique. The surgical technique is presented with illustrative clinical cases and intraoperative photographs, demonstrating the range of applications in anterior and central cranial base neurosurgery. CONCLUSION: Power drilling is generally not necessary for removal of the anterior clinoid process, optic canal roof, and optic strut. Rigorous study of preoperative computed tomographic scans/computed tomographic angiography scans, magnetic resonance imaging scans, and angiograms is essential to identify important anatomic relationships between the anterior clinoid process, optic strut, optic canal roof, and neighboring neurovascular structures. The “no-drill” technique eliminates the risks of direct power-drilling mechanical/ thermal injury and the risks of ultrasound-associated cranial neuropathies. The “no-drill” technique provides a direct, time-efficient, and efficacious approach to the paraclinoid/ parasellar/pericavernous area, using a simplified mechanical route. This technique is applicable to any neurosurgical diagnosis and approach in which anterior clinoidectomy is necessary. It is arguably the gentlest and most efficient method for exposing the paraclinoid/parasellar/pericavernous region 12).


Over a period of 3 years, anterior clinoidectomy was performed in 40 patients, 30 of whom harbored aneurysms (18 of the ICA and 13 of the basilar artery [one patient had two aneurysms]) and 10 of whom had tumors (four large pituitary tumors, four craniopharyngiomas, and two sphenoid ridge meningiomas). The ACP was removed extradurally in 31 cases and intradurally in nine cases. Extradural clinoidectomy was performed in all cases of pituitary adenoma and craniopharyngioma and in most cases of basilar artery aneurysm. Intradural clinoidectomy was performed in two cases of ICA-ophthalmic artery aneurysm, two cases of ICA-posterior communicating artery aneurysm, two cases of ICA cavernous aneurysm, one case of basilar artery aneurysm, and two cases of sphenoid ridge meningioma. The outcome was satisfactory in all patients, except for one patient who underwent clipping of a basilar tip aneurysm and suffered a thalamic and midbrain infarction. Three patients who underwent extradural clinoidectomy suffered a postoperative diminution of visual acuity or a visual field defect on the side of the clinoidectomy. These deficits may have been caused either by drilling of the ACP or by other operative manipulation of the optic nerve. Cerebrospinal fluid rhinorrhea, which required reoperation, occurred in one patient. The authors’ experience suggests that the extradural technique of ACP removal is easier and less time consuming than the intradural one and provides better operative exposure. It can be used routinely in treating lesions in the supra- and parasellar region 13).



Copeland WR, Van Gompel JJ, Giannini C, Eckel LJ, Koeller KK, Link MJ. Can Preoperative Imaging Predict Tumor Involvement of the Anterior Clinoid in Clinoid Region Meningiomas? Neurosurgery. 2015 Oct;77(4):525-30. doi: 10.1227/NEU.0000000000000873. PubMed PMID: 26120799.

Drake CG, Vanderlinden RG, Amacher AL. Carotid-ophthalmic aneurysms. J Neurosurg. 1968;29:24–31.

Hauser MJ, Gass H. Optic nerve pressure by aneurysm relieved by decompression of optic nerve; report of a case. AMA Arch Ophthalmol. 1952;48:627–31.

Dolenc VV. A combined epi- and subdural direct approach to carotid-ophthalmic artery aneurysms. J Neurosurg. 1985;62:667–72.

Mishra S, Leão B, Rosito DM. Extradural anterior clinoidectomy: Technical nuances from a learner’s perspective. Asian J Neurosurg. 2017 Apr-Jun;12(2):189-193. doi: 10.4103/1793-5482.145544. PubMed PMID: 28484528; PubMed Central PMCID: PMC5409364.

Noguchi A, Balasingam V, Shiokawa Y, McMenomey SO, Delashaw JB Jr. Extradural anterior clinoidectomy. Technical note. J Neurosurg. 2005 May;102(5):945-50. PubMed PMID: 15926728.

Lehmberg J, Krieg SM, Meyer B. Anterior clinoidectomy. Acta Neurochir (Wien). 2014 Feb;156(2):415-9; discussion 419. doi: 10.1007/s00701-013-1960-1. Epub 2013 Dec 10. Review. PubMed PMID: 24322583.

Kulwin C, Tubbs RS, Cohen-Gadol AA. Anterior clinoidectomy: Description of an alternative hybrid method and a review of the current techniques with an emphasis on complication avoidance. Surg Neurol Int. 2011;2:140. doi: 10.4103/2152-7806.85981. Epub 2011 Oct 12. PubMed PMID: 22059135; PubMed Central PMCID: PMC3205487.

Tayebi Meybodi A, Lawton MT, Yousef S, Guo X, González Sánchez JJ, Tabani H, García S, Burkhardt JK, Benet A. Anterior clinoidectomy using an extradural and intradural 2-step hybrid technique. J Neurosurg. 2018 Feb 23:1-10. doi: 10.3171/2017.8.JNS171522. [Epub ahead of print] PubMed PMID: 29473783.

Buttrick S, Morcos JJ, Elhammady MS, Wang AC. Extradural clinoidectomy for resection of clinoidal meningioma. Neurosurg Focus. 2017 Oct;43(VideoSuppl2):V10. doi: 10.3171/2017.10.FocusVid.17363. PubMed PMID: 28967317.

Romani R, Elsharkawy A, Laakso A, Kangasniemi M, Hernesniemi J. Complications of anterior clinoidectomy through lateral supraorbital approach. World Neurosurg. 2012 May-Jun;77(5-6):698-703. doi: 10.1016/j.wneu.2011.08.014. Epub 2011 Nov 7. PubMed PMID: 22120307.

Chang DJ. The “no-drill” technique of anterior clinoidectomy: a cranial base approach to the paraclinoid and parasellar region. Neurosurgery. 2009 Mar;64(3 Suppl):ons96-105; discussion ons105-6. doi: 10.1227/01.NEU.0000335172.68267.01. PubMed PMID: 19240577.

Yonekawa Y, Ogata N, Imhof HG, Olivecrona M, Strommer K, Kwak TE, Roth P, Groscurth P. Selective extradural anterior clinoidectomy for supra- and parasellar processes. Technical note. J Neurosurg. 1997 Oct;87(4):636-42. PubMed PMID: 9322855.

Cerebellopontine angle arachnoid cyst

Cerebellopontine angle arachnoid cyst


Middle cranial fossa is the most common site of intracranial arachnoid cysts, followed by the cerebellopontine angle (CPA) and suprasellar area.

Gardner et al., in 1960 attributed a embryonal atresia of the fourth ventricle as the cause of “arachnoid cyst” of the cerebellopontine angle 1).

Clinical features

They usually remain asymptomatic so they are often diagnosed incidentally during radiological evaluation for other reason 2).

As these cysts enlarge, they may compress surrounding structures and cause neurological symptoms. Patients may present with vague, nonspecific symptoms such as headache and ataxia. 3).

These cysts also can cause dysfunction of specific cranial nerves, including III, IV, VI (to cause diplopia), V (to induce trigeminal neuralgia), VII (to cause congenital or acquired facial paralysis), VIII (to cause hearing loss, tinnitus, vertigo), X (to result in hoarseness and dysphagia) 4) 5) 6).

Gurkas et al. report a patient with cranial nerve palsies and mirror movements found in upper extremities. They postulated that CPA arachnoid cyst compressing the brain stem and the pyramidal decussation may lead to mirror movements 7).


MRI (magnetic resonance imaging) scan techniques have led to CPA arachnoid cysts being more frequently diagnosed and with a higher degree of certainty. The need for further understanding of their natural history as well as for the development of a management rationale has been highlighted with this increased rate of diagnosis.

In the series of Alaani et al. these lesions have a characteristic location in the posterior-inferior aspect of the CPA below the facial and vestibulocochlear nerves. These cysts did not show change in size on repeated MRI scan and the patients’ symptoms did not progress over the period of follow up 8).

Differential diagnosis

A cerebellopontine angle lesion could be a vestibular schwannoma, meningioma, epidermoid cyst, or less likely, arachnoid cyst, metastasis, lower cranial nerves schwannoma, lipoma, hemangioma, paraganglioma, or vertebra-basilar dolichoectasia. Primary meningeal melanocytoma is a rare neoplasm, especially when it occurs at the cerebellopontine angle 9).

MRI is helpful in differentiating arachnoid cysts from those cystic lesions. If a pathologic cause of a retrocochlear disorder is suspected in a patient with a unilateral sensorineural hearing loss and tinnitus, MRI should be performed to evaluate the cerebellopontine angle.

On MRI, arachnoid cysts appear as smooth-surfaced lesions that in all magnetic resonance sequences exhibit a signal characteristic of CSF. In contrast, epidermoid cysts show mixed signals on FLAIR images and high signals on diffusion weighted images. Neurenteric cysts present high signals on T1-weighted images and cystic schwannomas show some foci of contrast enhancement on T1-weighted postcontrast images 10) 11).

The rising of a neuroglial cyst from the nerve sheath is a finding that brings other possible origins of neuroglial cysts into consideration 12).


The optimal surgical management of arachnoid cysts remains controversial.

Although surgery for these entities is controversial, arachnoid cysts can be treated surgically with open craniotomy for cyst removal, fenestration into adjacent arachnoid spaces, shunting of cyst contents, or endoscopic fenestration.

Alaani et al. support a conservative management approach to the majority of these cysts 13).

The definitive treatment for these arachnoid cysts is a retrosigmoid suboccipital craniotomy and microsurgical resection and fenestration of the cyst walls 14).


The risks of surgery are few, but complications (meningitis, hemiparesis, oculomotor palsy, subdural hematoma, grand mal epilepsy, and death) have been reported 15). 16) 17).

Olaya et al. report the first case of complete recovery from sensorineural hearing loss and facial weakness following endoscopic fenestration 18).

Case series

3 pediatric patients with CPA arachnoid cysts (2 with hearing loss and 1 with recurrent headaches) who underwent neurosurgical treatment at the authors’ institution.

Four pediatric patients were diagnosed with CPA arachnoid cysts at the International Neuroscience Institute during the period from October 2004 through August 2012, and 3 of these patients underwent surgical treatment. The authors describe the patients’ clinical symptoms, the surgical approach, and the results on long-term follow-up. RESULTS One patient (age 14 years) who presented with headache (without hearing deficit) became asymptomatic after surgical treatment. The other 2 patients who underwent surgical treatment both had hearing loss. One of these children (age 9 years) had recent-onset hypacusia and experienced complete recovery immediately after the surgery. The other (age 6 years) had a longer history (2 years) of progressive hearing loss and showed an interruption of the deficit progression and only mild improvement at the follow-up visit.

CPA arachnoid cysts are uncommon in pediatric patients. The indication and timing of the surgical treatment are fundamental, especially when a hearing deficit is present 19)


Alaani et al. present a series of five adult patients with different clinical presentations attributed to CPA arachnoid cysts. These lesions have a characteristic location in the posterior-inferior aspect of the CPA below the facial and vestibulocochlear nerves. These cysts did not show change in size on repeated MRI scan and the patients’ symptoms did not progress over the period of follow up. The findings would support a conservative management approach to the majority of these cysts 20).


Five patients (three male and two female patients) with a mean age of 5.6 years have been operated on at the Department of Neurosurgery, New York University Medical Center, USA. since 1980 till 1997.

All five arachnoid cysts compressed the cerebellum or brain stem. One patient had associated hydrocephalus. Three patients presented with refractory headaches associated with nausea and vomiting. The remaining two patients presented with cerebellar signs. No patient had an initial cranial neuropathy.

All patients underwent a retrosigmoid suboccipital craniotomy and microsurgical resection and fenestration of the cyst walls. One patient underwent two procedures. A cystoperitoneal shunt was inserted at the first operation. After the shunting procedure, the patient’s condition deteriorated; however, after the microsurgical resection and fenestration, his symptoms improved. With a mean 5.2-year follow-up, there has been no evidence of clinical or radiographic recurrence 21).


Two cases of arachnoid cysts of the cerebello-pontine angle. The otologic symptoms were unsteadiness, hearing fall and tinnitus. In the first case, the patient who presented a cerebellar syndrome was operated. Afterwards the hearing felt and he developed a transient hydrocephalus. The symptoms disappeared in 9 months. In the second cas, the patient was not operated. She was treated medically and supervised. Then the symptoms disappeared too. The authors review the paraclinic exams especially MR, relevant to the diagnosis and discuss the opportunity of a surgical operation 22).


Ten cases of arachnoid cysts of the ponto-cerebellar angle are presented. In most cases, local arachnoiditis is disclosed during surgery, directing the discussion toward acquired pathology, and perhaps toward local infection. The clinical symptoms are dominated by the cochleo-vestibular deficit, but the involvement of the V and the VII cranial nerves is inconstant and discreet. At the present time, C.T. scan allows a rapid diagnosis but the prognosis must be reserved, in account to the possibility of a local post operatory arachnoiditis 23).

Case reports


A 4-year-old boy with global developmental delay, esotropia, moderate aortic root dilation, genu valgum, and in-toeing gait. MRI brain for evaluation of neonatal hypotonia revealed a left cerebellopontine angle arachnoid cyst. He referred on newborn hearing screening, and diagnostic auditory brainstem response (ABR) showed left profound retrocochlear hearing loss. Surgical intervention for the arachnoid cyst was deferred, with spontaneous resolution at age two years without hearing recovery. CMA revealed a novel, de novo 5.1 Mb microdeletion of 22q13.31q13.33 not involving SHANK3, a gene typically deleted in PMS.

As diagnostic sensitivity improves, smaller chromosomal imbalances will be detectable related to milder or different phenotypes. They present two patients with novel deletions of chromosome 22q13 associated with multiple congenital anomalies and features distinct from PMS 24).


A 14-year-old previously healthy girl presented to our outpatient clinic with a 6-weeks history of frontal headache. They typically would start in the occipital region and then radiate bifrontally. The neurological examination was unremarkable. Magnetic resonance imaging revealed an extra-axial bilateral lesion in bilateral cerebellopontine angle, larger on left side. The lesions were homogeneously hypointenese on T1-weighted imaging and hyperintense on T2-weighted imaging without evidence of contrast enhancement and without evidence of restriction on diffusion-weighted imaging. No surgical treatment was indicated.

Bilateral arachnoid cysts of the cerebellopontine angle are very infrequent and the main indication for surgery is the existence of clinical symptoms or neurological deficit coincident with the locations of the cysts 25).


Petscavage et al. present the case of a 49-year-old woman who presented with acute, nonprogressive left sensorineural hearing loss and benign positional vertigo that was associated with an arachnoid cyst of the cerebellopontine angle. The presence of the lesion was documented by MRI examinations that were obtained 7 years apart. Arachnoid cysts at the cerebellopontine angle are usually found incidentally on MRI performed for unrelated reasons. However, if the arachnoid cyst displaces or compresses adjacent cranial nerves, symptoms may result. They review the salient imaging features of arachnoid cysts that allow their differentiation from other lesions of the cerebellopontine angle 26).

Gurkas et al. report a patient with a CPA arachnoid cyst. He presented with cranial nerve palsies and mirror movements found in upper extremities. They postulated that CPA arachnoid cyst compressing the brain stem and the pyramidal decussation may lead to mirror movements, and conclude that mirror movements can be associated with CPA arachnoid cyst 27).

A 71-year old woman presenting with a right hemifacial spasm and an ipsilateral arachnoid cyst. Preoperative magnetic resonance imaging findings suggested a neurovascular compression caused by displacement of the facial-acoustic complex and the anterior inferior cerebellar artery by the cyst. Cyst excision and microvascular decompression of the facial nerve achieved permanent relief. The existing cases of arachnoid cysts causing hemifacial spasm are reviewed and the importance of a secondary neurovascular conflict identification and decompression in these cases is highlighted 28).

Trigeminal Neuralgia in a Child With a Cerebellopontine Angle Arachnoid Cyst 29).

Sharma et al. report two cases of bilateral CPA AC with their pathophysiology and review of literature 30).


Visagan et al. first report a CPA arachnoid cyst causing TGN in a paediatric case 31).


A 62-year-old man complaining of vertigo and progressive hearing loss was diagnosed with an arachnoid cyst at the right cerebellopontine angle based on magnetic resonance imaging (MRI). In this case-report, we used computed tomography (CT) cisternography to determine whether the arachnoid cyst communicated with the cerebrospinal fluid (CSF) space. Differentiating between a noncommunicating and communicating arachnoid cyst is required for presurgical evaluation. CT cisternography is a less used but reliable radiological technique for determining the presence of communication, and could therefore be included in the diagnostic work-up of arachnoid cysts. The patient underwent surgery with fenestration of the arachnoid cyst; his vertigo improved and his hearing was preserved 32).

Superior oblique myokymia (SOM) is a rare disorder with an unclear pathogenesis. We describe a first reported case of chronic disabling SOM in association with a cerebellopontine angle arachnoid cyst, who had a gradual and eventually complete symptomatic resolution 8 months following cyst marsupialisation. Among other aetiologies, SOM may therefore be due to abnormal CSF flow dynamics resulting in structural compromise of the nerve 33).


A 7-month-old infant presented to the hospital with a history of delayed milestones and an abnormal increase in head circumference. Magnetic resonance images and CT scans of the brain showed a large CSF cavity involving the entire brainstem and a right CPA arachnoid cyst causing obstruction of the fourth ventricle and dilation of the lateral and third ventricles. Cerebrospinal fluid diversion was performed by direct communication from the syringobulbia cavity to the left lateral ventricle and from the left lateral ventricle through another ventricular catheter; external ventricular drainage was performed temporarily for 5 days. Communication between the syrinx and arachnoid cyst was confirmed. Clinically, there was a reduction in head circumference, and serial MR imaging of the brain showed a decrease in the size of the syrinx cavity and the ventricle along with opening of the normal CSF pathways. The postoperative course was uneventful, and no further intervention was necessary. On follow-up of the child at 3 years, his developmental milestones were normal. Surgical intervention for this condition is mandatory. The appropriate type of surgery should be performed on the basis of the pathophysiology of the developing syringobulbia 34).

A 47-year-old woman complaining of sharp and lancinating pain in the right periauricular and submandibular areas visited our hospital. Swallowing, chewing, and lying on her right side triggered the pain. Her neurologic examination revealed no specific abnormalities. The results of routine hematologic and blood chemistry studies were all within normal limits. Carbamazepine and gabapentin were given, but her symptoms persisted. Her pain was temporarily relieved only by narcotic pain medication. MRI showed an arachnoid cyst located in the right cerebellomedullary cistern extending to the cerebellopontine cistern. Cyst removal was performed via a right retrosigmoid approach. Lateral suboccipital craniotomy was performed using the right park-bench position. After opening the dura and cerebellopontine angle, the arachnoid cyst was exposed. The arachnoid cyst was compressing the flattened lower cranial nerves at the right jugular fossa. Her symptoms resolved postoperatively. Two months after the operation, she was completely free from her previous symptoms 35).


A rare case of cerebellopontine angle arachnoid cyst manifesting as hemifacial spasm (HFS) is reported. The patient is a 42-year-old woman with 10-month history of left HFS. A preoperative magnetic resonance imaging scan showed a well-demarcated area, hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging, in the left cerebellopontine angle, without contrast enhancement, resembling an arachnoid cyst. METHODS: The cyst was excised with microneurosurgical technique and the facial, vestibular, and acoustic nerves were completely decompressed from the arachnoid wall. RESULTS: The postoperative course was uneventful, and the left HFS disappeared immediately. Histologically, the cyst wall was a typical arachnoidal membrane. Ten months after surgery, the patient is symptom free. CONCLUSION: It is well-known that in approximately 10% of cases, trigeminal neuralgia can be caused by a space-occupying mass. However, the fact that HFS can also be caused by organic lesions as well as neurovascular compression is less well-known. Although the occurrence of tumor compression causing HFS has been previously recognized, cerebellopontine angle cysts have very rarely been described. The observation of a patient with a cerebellopontine angle arachnoid cyst causing HFS prompted us to review the literature relative to HFS caused by an organic lesion rather than neurovascular compression 36).


a patient with a CPA arachnoid cyst who presented with hoarseness (unilateral vocal cord paralysis) and dysphagia secondary to isolated compression of the vagus nerve. This rare presentation of a CPA arachnoid cyst has not been reported previously. CLINICAL PRESENTATION: The patient described is a 50-year-old man who experienced a precipitous onset of hoarseness and dsyphagia. An otolaryngological evaluation revealed right-sided vocal cord paralysis. Brain magnetic resonance images displayed a cystic mass at the right CPA and anterior displacement of the vagus nerve. INTERVENTION: The patient underwent retrosigmoidal craniectomy with cyst fenestration, which was well tolerated. Intraoperatively, Cranial Nerve X was found splayed over the cyst and was consequently decompressed. CONCLUSION: Postoperatively, the patient’s dysphagia completely resolved. However, the results of a laryngeal electromyocardiogram revealed minimal evidence of recovery in the affected vocal fold, and the patient continued to suffer from dysphonia. Although CPA arachnoid cysts are rare, they should be considered when a patient presents with an isolated cranial nerve palsy. Treatment options include cyst fenestration and cranial nerve decompression 37).


A 51 years old female is reported who was diagnosed by IRM of a 4,5 x 2 cm arachnoid cyst, situated on the left cerebello-pontine angle, with tinnitus, hearing loss and vertigo that mimicked a Meniere’s attack. We think thees benign tumors must be included in the differential diagnosis of Meniere’s disease because they can be indistinguishable from it clinically 38).


Higashi et al., reported the first case of hemifacial spasm with an ipsilateral cerebellopontine angle arachnoid cyst in a 25-year-old man. The patient underwent evacuation of the arachnoid cyst by a partial membranectomy without any beneficial effect, and finally got rid of the hemifacial spasm by reexploration and microvascular decompression of the facial nerve. The operative findings and results revealed that the cyst produced deviation of the ipsilateral posterior inferior cerebellar artery, which was secondarily in contact with the root exit zone of the facial nerve 39).

A 17-month-old girl who developed two cerebellopontine angle arachnoid cysts after posterior fossa surgery for a brain tumor. After surgical excision of the tumor the child developed a left cerebellopontine angle cyst. This was treated through a suboccipital craniectomy by evacuating the cyst and excising the cyst wall. Two months later the child developed a second right-sided cerebellopontine angle cyst. It was treated by inserting a cystoperitoneal shunt. This article presents the case with radiological evidence of the acquired nature of the cysts. It also includes a brief review of the clinical presentation, pathogenesis, radiological evaluation, and surgical treatment of arachnoid cysts with emphasis on those occurring in the posterior fossa 40).


A case of an arachnoid cyst in the cerebellopontine angle manifesting as contralateral trigeminal neuralgia is presented. Decompression and excision of the lesion resulted in total relief of symptoms. The possible causes of contralateral trigeminal neuralgia are briefly reviewed, and the surgical treatment of this entity is discussed 41).


A case of a cerebellopontine angle arachnoid cyst spontaneously disappeared is reported. A 1-year-and-11-month old boy was suffered from sudden onset of left facial palsy. CT scan demonstrated dilatation of left internal auditory canal and a cystic lesion in the left cerebellopontine angle. Neurological examination disclosed only left facial palsy and left hearing loss. There was no signs and symptoms of increased intracranial pressure. He was followed up by CT scan. Repeated CT scan showed non-enhanced cystic lesion, the attenuation value of which was similar to that of cerebrospinal fluid. The cyst expanded gradually, and the brain stem was severely compressed. Then operation was planned under the diagnosis of left cerebellopontine angle arachnoid cyst about 2 years after the onset. But CT scan performed before operation showed disappearance of the cyst. Without operation the patient was followed by CT scan. There is no recurrence of the cyst. Natural history of arachnoid cyst will be well understood with repeated CT scan 42).



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Esthesioneuroblastoma (ENB)

AKA: Olfactory neuroblastoma.

Esthesioneuroblastoma is a rare malignant tumor of sinonasal origin. These tumors typically present with unilateral nasal obstruction and epistaxis, and diagnosis is confirmed on biopsy.


Case series

Nineteen patients from Brescia received endoscopic resection with transnasal craniectomy and subpial dissection (ERTC-SD) and 11 had pathological-proven brain invasion. Histologies were 6 olfactory neuroblastomas (ONB), 3 neuroendocrine carcinomas, and 2 intestinal-type adenocarcinomas. Mean follow-up was 21.9 months. Three-year overall, local recurrence-free, and distance recurrence-free survivals were 65.5%, 81.8%, and 68.2%, respectively. Overall and distant recurrence-free survivals were significantly better in patients with ONB (P = 0.032 and P = 0.013, respectively). Hospitalization ratio was 4.1%. Complication rate was 10.5%.

In selected nasal-ethmoidal tumors with brain invasion, ERTC-SD can provide good local control, satisfactory survival, and limited morbidity 1).

Klironomos et al., presented the use of pure EEA in the management of ENB in the Toronto Western Hospital, along with a literature review. They retrospectively reviewed the clinical, radiology and pathology records of patients with ENB treated during the period July 2006 to January 2016. During the above period, ten patients with ENB were treated using pure EEA. The mean age was 47.5 years. The gender distribution was: eight males, two females. The most common presenting symptoms were nasal obstruction and discharge or epistaxis (8/10). The mean duration of symptoms was 1.5 years. All patients had preoperative confirmation of ENB by biopsy. Five patients received neoadjuvant radiation and four underwent postoperative radiation. One patient did not receive any radiotherapy and no patient received chemotherapy. Gross total resection was achieved in all patients and intraoperative microscopically negative surgical margins achieved in 9/10 (90%). No major intraoperative complications occurred. The most common postoperative complication was nasal infection. Cerebrospinal fluid leak was noted in one patient. During the follow-up period of 6-120 months (mean 74.8) two cases of neck lymph node recurrence were observed. No deaths due to the disease occurred during the follow-up period. Pure EEA offer excellent results in the management of ENB. Neoadjuvant radiation treatment is promising although more studies need to establish its role 2).

There is a scarcity of data about different treatment strategies. Intensity modulated radiotherapy (IMRT) and carbon ion radiotherapy (CIRT) are advanced radiation techniques that might improve local tumor control.

In a retrospective analysis of 17 patients with ENB (Kadish stage ≥ C: 88%; n = 15). Four patients had already undergone previous radiotherapy (RT). The treatment consisted of either IMRT (n = 5), CIRT (n = 4) or a combination of both techniques (n = 8). Median follow-up was 29 months. (3) Results: In patients that had not been irradiated before (n = 13), calculated overall survival (OS) and progression free survival (PFS) rates after 48 months were 100% and 81% respectively (Kaplan-Meier estimates). Two of four patients that underwent reirradiation died after RT, presumably due to tumor progression. Besides common toxicities, five patients (30%) showed mostly asymptomatic radiation-induced brain changes, most likely due to a disturbance of the blood-brain barrier.

The results demonstrate that IMRT, CIRT, a combined approach of IMRT and CIRT as well as reirradiation with CIRT seem to be feasible and effective treatment methods in ENB. 3).

ENB is safely and effectively treated with craniofacial resection (CFR) followed by proton beam irradiation. The high incidence of regional metastases warrants strong consideration for elective neck irradiation. Proton beam radiation is associated with lower rates of severe late-radiation toxicity than conventional radiotherapy 4).

The National Cancer Database (NCDB) was used to identify patients diagnosed with ENB between 2004 to 2015. Patients were excluded based on the ability to properly stage their disease as well as the availability of treatment data.

Eight-hundred eighty-three patients had sufficient data for analysis. On multivariate analysis, age and government insurance were associated with primary surgical treatment, whereas tumor stage, gender, race, hospital type and volume, and comorbidity score were not. Age, charlson-deyo comorbidity (CDCC) score, hospital volume, and nodal status were found to be predictors of survival. Multivariate-analysis controlling for stage failed to demonstrate clear survival differences between staging in both TNM and Kadish systems. T-stage and the presence of regional nodal metastasis were associated with an increased risk of positive margins on multivariate analysis.

Although primary surgical management and positive margins can be predicted by certain patient and tumor factors, clinical staging systems for ENB poorly predict prognosis over a 10-year horizon 5).

Esthesioneuroblastoma case reports

A case of non-contiguous meningeal recurrence of olfactory neuroblastoma presenting as a giant frontal mass. A 66-year-old woman was admitted with a left nasal intranasal localized tumor without cranial extension and gross total removal was achieved. Pathological examination showed olfactory neuroblastoma and radiation therapy was added in a limited region of the removal cavity. Radiological follow-up continued for 10 years and there was no local recurrence. Sixteen years after radiation therapy, the patient found a slight frontal mass gradually growing. Magnetic resonance imaging revealed an enhanced mass lesion of 7 cm in thickness and 9 cm in diameter associated with marked thickness of the frontal bone, intradural cystic mass compressing the bilateral frontal lobe, and no local recurrence. A second operation was performed followed by radiotherapy and we diagnosed no-contiguous meningeal recurrence of metastatic olfactory neuroblastoma. Olfactory neuroblastoma is a locally aggressive tumor. Although metastasis of this tumor has been reported, non-contiguous spread to the dura is rare. Understanding the route of remote metastasis and careful evaluation after primary treatment are needed to avoid misdiagnosis and treatment delays 6).



Mattavelli D, Ferrari M, Bolzoni Villaret A, Schreiber A, Rampinelli V, Turri-Zanoni M, Lancini D, Taglietti V, Accorona R, Doglietto F, Battaglia P, Castelnuovo P, Nicolai P. Transnasal endoscopic surgery in selected nasal-ethmoidal cancer with suspected brain invasion: Indications, technique, and outcomes. Head Neck. 2019 Jan 12. doi: 10.1002/hed.25621. [Epub ahead of print] PubMed PMID: 30636181.

Klironomos G, Gonen L, Au K, Monteiro E, Mansouri A, Turel MK, Witterick I, Vescan A, Zadeh G, Gentili F. Endoscopic management of Esthesioneuroblastoma: Our experience and review of the literature. J Clin Neurosci. 2018 Dec;58:117-123. doi: 10.1016/j.jocn.2018.09.011. Epub 2018 Oct 16. Review. PubMed PMID: 30340976.

Liermann J, Syed M, Held T, Bernhardt D, Plinkert P, Jungk C, Unterberg A, Rieken S, Debus J, Herfarth K, Adeberg S. Advanced Radiation Techniques in the Treatment of Esthesioneuroblastoma: A 7-Year Single-Institution’s Clinical Experience. Cancers (Basel). 2018 Nov 20;10(11). pii: E457. doi: 10.3390/cancers10110457. PubMed PMID: 30463343; PubMed Central PMCID: PMC6267306.

Herr MW, Sethi RK, Meier JC, Chambers KJ, Remenschneider A, Chan A, Curry WT, Barker FG 2nd, Deschler DG, Lin DT. Esthesioneuroblastoma: an update on the massachusetts eye and ear infirmary and massachusetts general hospital experience with craniofacial resection, proton beam radiation, and chemotherapy. J Neurol Surg B Skull Base. 2014 Feb;75(1):58-64. doi: 10.1055/s-0033-1356493. Epub 2013 Sep 20. PubMed PMID: 24498591.

Joshi RR, Husain Q, Roman BR, Cracchiolo J, Yu Y, Tsai J, Kang J, McBride S, Lee NY, Morris L, Ganly I, Tabar V, Cohen MA. Comparing Kadish, TNM, and the modified Dulguerov staging systems for esthesioneuroblastoma. J Surg Oncol. 2019 Jan;119(1):130-142. doi: 10.1002/jso.25293. Epub 2018 Nov 22. PubMed PMID: 30466166.

Saito A, Sasaki T, Inoue T, Narisawa A, Inoue T, Suzuki S, Ezura M, Uenohara H. Non-contiguous Meningeal Recurrence of Olfactory Neuroblastoma: A Case Report and Literature Review. NMC Case Rep J. 2018 Jun 28;5(3):69-72. doi: 10.2176/ eCollection 2018 Jul. PubMed PMID: 30023143; PubMed Central PMCID: PMC6048349.
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