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Original Article

Vascular loops in the cerebellopontine angle cistern and their role in causing compression symptoms of 7th and 8th nerves as determined in Magnetic Resonance Imaging

1Senior resident, 2Assistant Professor, 3Professor and Head, Department of Radiology, 4Assistant professor, Department of Neurosurgery, Kamineni Institute of Medical Sciences, Narketpally, Nalgonda District, Telangana State, India.

Abstract

Introduction: Neurovascular compression syndrome is a group of symptoms seen as a result of compression or irritation of the nerve root by aberrant or tortuous vessel. The vessels in the cerebellopontine (CP) angle are classified into four types depending on their extension into the CP angle and formation of a loop. Neurovascular conflict (NVC) is defined as an "abnormal" contact between a vessel and a cranial nerve. Three-dimensional constructive interference in steady state (CISS) is routinely used in the assessment of cerebellopontine angle and its fine structures like 7th and 8th cranial nerves.

Aim: To identify the most common type of vasculature in the cerebellopontine angle and the most common type implicated in neurovascular compression by identifying the conflict rather than just contact of the vessel with the nerve.

Materials and methods: 100 patients (with 200 sides) were taken for scanning with defined criteria for study purpose. Out of them, 64 patients had unilateral symptoms, the symptomatic side was taken as diseased and asymptomatic side was taken as controls. 18 patients with bilateral symptoms were taken as diseased and 18 patients with no symptoms of cranial nerve compression were taken as controls. Out of the study subjects, 64 patients were with unilateral symptoms, 18 patients with bilateral symptoms and 18 patients with no symptoms of cranial nerve compression (A total of 100 sides diseased and 100 sides controls were studied). Most common type causing neurovascular conflict was studied and compared between cases and controls and the statistical significance of which was assessed using Chi square test.

Results: Most common pattern of vascularity in all cases together was type IA (44%), in cases with 7th nerve compression symptoms is type IA (82%) and in cases with 8th nerve compression symptoms was type IB (50%). Neurovascular contact noted in 97% cases with 7th nerve compression symptoms out of which there was conflict in 88.2%. In cases with 8th nerve compression symptoms, neurovascular contact was noted in 65.15% and conflict noted in 27.27%. This difference was statistically significant. Conclusion: Most common vascular pattern is type IA in cases, type IB in controls and type IB in cases and controls together. Vascular type implicated in 7th nerve compression was type IA and there is no statistically significant relation between the vascular pattern and nerve compression in 8th nerve.

Key words:Neurovascular Compression, Neurovascular Conflict, 7th and 8th Nerves, Vascular Loops