Neuro-ophthalmology, neuro-otology, and cranial nerve disorders
Neuro-ophthalmology, neuro-otology, and cranial nerve disorders
The exam tests pupil and visual pathway localization, diplopia, nystagmus, hearing loss, and cranial nerve palsies. A painful third nerve palsy with pupil involvement suggests compressive aneurysm and needs urgent vascular imaging. Painless pupil-sparing third nerve palsy is often microvascular but must be monitored. Optic neuritis causes painful monocular vision loss with decreased color vision and a relative afferent pupillary defect. In acute vestibular syndrome, HINTS testing can distinguish central from peripheral causes: normal head impulse, direction-changing nystagmus, or skew deviation suggests central lesion. Bell palsy is lower facial weakness with forehead involvement; treat early with corticosteroids.
Worked example
A 60-year-old has acute diplopia, ptosis, and a dilated unreactive pupil. Reasoning: compressive third nerve palsy until proven otherwise. Obtain urgent CTA or MRA; do not simply observe as diabetic palsy because pupil involvement is a red flag.
Traps
Do not miss pupil-involving third nerve palsy; do not use HINTS in patients with obvious peripheral vestibular disease without caution; do not delay steroids in Bell palsy; do not overlook sudden sensorineural hearing loss; do not confuse Horner syndrome with third nerve palsy.