c c n s . o r gCysts of the ligamentum flavum are unusual causes of spinal compression. Their etiology and histopathologic classification have yet to be fully elucidated. We report our experience of four cases of ligamentum flavum cysts occurring in the lumbar spine and discuss some of the etiologies and possible pathophysiologic mechanisms for their development. CASE REPORTSAn outline of the cases is contained in the Table, and imaging examples are shown in Figure 1. Case 1The patient was an 82-year-old woman referred for recent onset of right-sided sciatica involving mostly the S1 distribution and causing major incapacitation because of severe pain. There was no pain on coughing; however, she had increased urinary frequency at night. On examination, motor function was normal and there was no sensory disturbance on examination of the legs. Reflexes were hypoactive in the right leg with plantar reflexes downgoing.Computerized tomography (CT) imaging of the lumbo-sacral spine showed significant degenerative disease in the lumbar spine, as well as an epidural mass occupying the L5-S1 region, with a small posterocentral subligamentous hernia, possibly representing a synovial or arachnoid cyst but also compatible with a benign cystic tumour such as a schwannoma. Subsequent magnetic resonance imaging (MRI) demonstrated a voluminous epidural cystic lesion compressing the cauda equina to the right of the sac at L5-S1, compatible with a synovial cyst of the ligamentum flavum. In light of the acuity and degree of incapacitation of the disease, the patient was hospitalized for urgent laminectomy with microsurgical removal of the cyst.ABSTRACT: Background: Cysts of the ligamentum flavum are rare and unusual causes of spinal compression. Methods: We report our experience of four cases of ligamentum flavum cysts occurring in the lumbar spine and discuss some of the possible etiologies and pathophysiologic mechanisms according to the available literature. Conclusion: This entity is clearly different from the synovial facetjoints or ganglion cysts.RÉSUMÉ: Sténose spinale lombaire incapacitante causée par un kyste du ligament jaune. Introduction: Les kystes du ligament jaune sont rares et causent très rarement une compression spinale. Méthodes: Nous rapportons notre expérience au sujet de quatre cas de kystes du ligament jaune au niveau lombaire et nous discutons de l'étiologie et de la physiopathologie de cette entité à la lumière de la littérature actuelle. Conclusion: Cette pathologie est nettement différente des kystes synoviaux des articulations facettaires ou des kystes ganglionnaires.

Among cases of cerebellopontine angle (CP) lesions, vascular lesions involving the internal auditory canal are extremely rare. We report a distal mycotic fusiform pseudoaneurysm of the anterior inferior cerebellar artery that simulated an acoustic neuroma on presentation. Its surgical management is described and possible pathophysiologic mechanisms are discussed along with the currently available literature. CASE REPORTA 60-year-old woman in otherwise healthy condition experienced onset of acute dizziness in the context of a twenty year history of rightsided tinnitus that had recently accentuated. There was no history of chronic mastoiditis. She had no facial nerve disfunction or any hearing complaints, and audiological assessment was excellent (speech reception threshold (SRT) 10 dB, speech discrimination score (SDS) 92%). Magnetic resonance imaging (MRI) examination (Figure 1) revealed a 6-7 mm lesion in the proximal internal auditory canal occupying approximately 1/3 of the porus and minimally protruding into ABSTRACT: Background: Among cases of cerebellopontine angle lesions, vascular lesions involving the internal auditory canal are extremely rare. We report a distal fusiform mycotic pseudoaneurysm of the anterior inferior cerebellar artery (AICA) that simulated an acoustic neuroma on presentation. Methods: A 60-year-old woman was investigated for recent onset of acute dizziness. Laboratory and radiographic investigations are presented, as well as the surgical management of the patient and pathological examination of the aneurysm. Conclusions: An exceptionally rare case of distal mycotic intracanalicular pseudoaneurysm of the AICA with intraluminal thrombus and fusiform anatomy is described. In our review of the literature (1966-present), only five other intracanalicular AICAaneurysms were encountered, none of which were infectious in etiology. The possible pathophysiologic mechanisms of distal AICA-aneurysms are discussed along with the currently available literature. CASE REPORTthe CP angle. The lesion was hyperintense in T1 and enhancing with gadolinium injection. On T2-weighted MRI, the lesion was found to be hypointense. On the basis of these findings a pre-operative diagnosis of right intracanalicular acoustic neuroma was made by both neuroradiologists and the neuro-otology team. In view of the excellent hearing, an attempt at hearing preservation was planned for removal of the mass. OperationThe patient was placed in the left park-bench position with the appropriate needle electrodes placed for intraoperative monitoring of the https://www.cambridge.org/core/terms. https://doi

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