1. Within the pons, causes include a. Multiple sclerosis b. Infarct c. Mass (eg, glioma or tuberculoma)
d. Wernicke's syndrome
Look for ipsilateral
• Seventh nerve lesion
• Horner's syndrome
• Facial hypesthesia
• Internuclear ophthalmoplegia
Look for contralateral
• Nystagmus (possibly in more than one direction)
• Hemisensory pain and temperature loss in the trunk or limbs
2. At the base of the brain, causes include a. Acoustic neuroma b. Meningitis c. Subarachnoid hemorrhage d. Compression of an aneurysm or anomalous vessel e. Basal meningioma f. Nasopharyngeal carcinoma g. Chordoma h. Wegener's granulomatosis
Look for signs of involvement of the fifth, seventh, and eighth cranial nerves.
3. In relation to the petrous portion of the temporal bone, causes include a. Infection, fracture, or tumor of the petrous bone
Look for pain, paresthesia, or hyperesthesia of the face (same side) and deafness.
4. In the cavernous sinus/superior orbital fissure, causes include a. Aneurysm (carotid)
b. Carotid—cavernous fistula (trauma)
c. Tumor—pituitary, meningioma, or nasopharyngeal carcinoma d. Tolosa-Hunt syndrome e. Cavernous sinus thrombosis f. Mucormycosis (in diabetics)
Look for signs of involvement of the third and fourth cranial nerves as well as first and second divisions of the fifth.
5. In the orbit, causes include a. Tumor b. Trauma
6. Common and not so common causes, but with an uncertain site, include a. Postviral infection (especially in children)
Was this article helpful?