| More common causes according to location | Common accompanying features* |
| Nuclear/fascicular lesions in the pons |
- Demyelinating
- Ischemic
- Neoplastic
| - Horizontal gaze palsy; ipsilateral facial palsy; other brainstem signs including hemiparesis, hemisensory loss, and/or dysmetria
|
| | - Encephalopathy, gait ataxia
|
| Subarachnoid space lesions |
- Increased intracranial pressure from any cause including IIH
| - Maybe bilateral, maybe associated with signs of increased intracranial pressure
|
| | - Isolated cranial nerve palsy, often with ipsilateral periorbital pain
|
- Aneurysm (causing nerve compression)
| - Usually isolated cranial nerve palsy if unruptured aneurysm
|
- Meningeal inflammation or infiltration from infection, neoplasia, or inflammatory process
| - Meningismus, other cranial mononeuropathies
|
- Low intracranial pressure
| - Headache, nausea, and vomiting worse with upright posture
|
| Petrous apex lesions |
- Neoplasm/tumor
- Infection or inflammatory (Gradenigo)
- Thrombosis of inferior petrosal sinus
- Traumatic, basilar skull, petrous apex fracture
| - Facial pain (especially retro-orbital); fifth, seventh, eighth (deafness) cranial nerve involvement
|
| Cavernous sinus lesions |
- Cavernous sinus thrombosis
- Cavernous sinus fistula
- Neoplasm/tumor
- Pituitary adenoma
- Infections
- Inflammatory (including Tolosa-Hunt syndrome)
- Internal carotid artery aneurysm or dissection
| - Impaired function of third, fourth, and fifth cranial nerves
- +/– ipsilateral Horner syndrome
|
| Orbital lesions |
- Neoplastic
- Infectious
- Inflammatory (including orbital pseudotumor)
| - Variably affected cranial nerve III, IV, V1
- Proptosis, chemosis, compressive optic neuropathy
|
