False Localising Signs – Bilateral 6th Nerve Palsies — SCE Neurology MCQ

Correct answer: A — Raised intracranial pressure stretches the long intracranial course of both abducens nerves

The best answer is “Raised intracranial pressure stretches the long intracranial course of both abducens nerves”. The abducens nerve is vulnerable to downward brain displacement and stretch, so bilateral palsies may reflect pressure rather than a focal pontine lesion. “Direct compression of both abducens nuclei by the optic discs” remains a plausible alternative in a different presentation, but it does not fit the decisive finding or management threshold here. “Neuromuscular-junction failure caused by cerebrospinal-fluid obstruction” remains a plausible alternative in a different presentation, but it does not fit the decisive finding or management threshold here. “Bilateral medial-longitudinal-fasciculus infarction from venous congestion” remains a plausible alternative in a different presentation, but it does not fit the decisive finding or management threshold here. “Selective cavernous-sinus inflammation caused by papilloedema” remains a plausible alternative in a different presentation, but it does not fit the decisive finding or management threshold here.

Reference: Consensus guidelines on management of idiopathic intracranial hypertension: https://pmc.ncbi.nlm.nih.gov/articles/PMC6166610/