17.2 Function
The abducens nerve has only GSE motor fibers. It innervates the lateral rectus muscle, the activation of which causes abduction of the eye allowing for conjugate horizontal gaze.
17.3 Pathology
Individual symptoms: Damage to the abducens nerve results in the following symptoms depending on location:
Nuclear lesions: Mass lesions that compress at the skull base such as meningioma, epidermoid cyst, arachnoid cyst, and schwannoma can cause compression at the level of the dorsal pons. A nuclear lesion always causes impairment of the ipsilateral gaze of both eyes due to interneuron connections with the contralateral CN III through the medial longitudinal fasciculus. Inflammatory and ischemic pontine (Millard-Gubler syndrome) lesions also cause fascicular parenchymal lesions causing ipsilateral gaze deficit.
Cisternal lesions: Due to its unusually lengthy course of the nerve, CN VI is particularly prone to traumatic injury. Changes in intracranial pressure (in particular idiopathic intracranial hypertension), diabetic ischemia, aneurysmal compression from basilar artery or neurovascular conflict (e.g., presence of dolicho basilar artery), neoplasms (tentorium of clival meningioma), and idiopathic hypertrophic pachymeningitis are some of the most frequent etiologies. Miller-Fischer variant of Guillain-Barrè can cause CN VI palsy.
Cavernous segment: Carotid-cavernous sinus fistula, cavernous sinus thrombosis, and carotid artery aneurysms result in mass effect-induced CN VI palsy [2].Related posts:
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