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1 ⇓ ⇓ ⇓– 5 The most common neurovascular compression syndromes are trigeminal neuralgia (TN compression of CN V), hemifacial spasm (HFS CN VII), vestibulocochlear neuralgia (CN VIII), and glossopharyngeal neuralgia (GN CN IX). Neurovascular compression syndrome (NVCS) is defined as a direct contact with mechanical irritation of cranial nerves (CNs) by blood vessels. Although symptomatic neurovascular compression syndromes may also occur if the neurovascular contact is outside the transition zone, symptomatic neurovascular compression syndromes are more common if the neurovascular contact occurs at the transition zone or central myelin section, in particular when associated with nerve displacement and atrophy.ĪBBREVIATIONS: AICA anterior inferior cerebellar artery CN cranial nerve GN glossopharyngeal neuralgia HFS hemifacial spasm NVC neurovascular compression NVCS neurovascular compression syndrome REZ root entry/exit zone TN trigeminal neuralgia TZ transition zone The transition zone overlaps the root entry zone close to the brain stem in cranial nerves V, VII, and IX, yet it is more distal and does not overlap the root entry zone in cranial nerve VIII. Glossopharyngeal neuralgia (cranial nerve IX) has an incidence of 0.5/100,000, a transition zone of 1.5 mm, with symptomatic neurovascular compression typically proximal. Vestibular paroxysmia (cranial nerve VIII) has an unknown incidence, a transition zone of 11 mm, with symptomatic neurovascular compression typically at the internal auditory canal. Hemifacial spasm (cranial nerve VII) has an incidence of 1/100,000, a transition zone of 2.5 mm, with symptomatic neurovascular compression typically proximal. Trigeminal neuralgia (cranial nerve V) has an incidence of 4–20/100,000, a transition zone of 4 mm, with symptomatic neurovascular compression typically proximal. The transition zone between the central and peripheral myelin is the most vulnerable region for symptomatic neurovascular compression syndromes.

Not all cases of neurovascular contact are clinically symptomatic. SUMMARY: Neurovascular compression syndromes are usually caused by arteries that directly contact the cisternal portion of a cranial nerve.