Midbrain: | | | | |
Nuclear | (+/−) Bilateral pupil involvement | Supranuclear ocular motility deficits | Infectious: | |
| (+/−) Bilateral ptosis | | Lyme disease | Usually present |
| Incomplete paresis (isolated extraocular muscle) | | Syphilis | Variable |
| | | Inflammatory: | |
| Contralateral superior rectus muscle paresis | | Multiple sclerosis | Variable |
| | | Sarcoidosis | Present |
| | | Autoimmune vasculitis | Variable |
| | | Neoplastic: | |
| | | Primary brain tumor | Variable |
| | | Metastasis | Present |
| | | Lymphoma | Present |
| | | Traumatic | Usually none |
| | | Vascular: | |
| | | Ischemia | Variable |
| | | Cavernous angioma | Usually none |
| | | Arteriovenous malformation (AVM) | Enhancement of the AVM only |
Fascicular | Complete or incomplete (divisional) paresis | Cerebellar Ataxia: Nothnagel’s | Same as above | |
| | Contralateral dyskinesia: Benedickt’s | | |
| (+/−) Pupil involvement | Contralateral hemiparesis: Weber’s | | |
Subarachnoid space | Complete or incomplete (divisional) paresis | Multiple cranial neuropathies | Infectious: | |
Meningeal irritation | Bacterial, viral or fungal meningitis | Present |
| (+/−) Pupil involvement | Mental status changes | Syphilis | Variable |
| | Raised intracranial pressure | Lyme disease | Usually present |
| | | HIV | Usually present |
| | | Inflammatory: | |
| | | Multiple sclerosis | Variable |
| | | Sarcoidosis | Present |
| | | Inflammatory demyelinating polyneuropathy | Variable |
| | | Neoplastic: | |
| | | Lymphoma | Present |
| | | Leukemia | Present |
| | | Meningeal carcinomatosis | Present |
| | | Schwannoma | Present |
| | | Traumatic | Usually none |
| | | Vascular: | |
| | | Ischemia | Variable |
| | | Aneurysm | Enhancement of the Aneurysm only |
| | | Other: | |
| | | Ophthalmoplegic migraine | Present |
Cavernous sinus/superior orbital fissure | Complete or incomplete (divisional) paresis | Multiple cranial neuropathies | Infectious: | |
| Visual Loss | Bacterial, viral or fungal meningitis | Present |
(+/−) Pupil involvement | Proptosis | Syphilis | Variable |
| | | Lyme disease | Usually present |
| | | HIV | Usually present |
| | | Inflammatory: | |
| | | Tolosa-Hunt syndrome | Present |
| | | Sarcoidosis | Present |
| | | Neoplastic: | |
| | | Lymphoma | Present |
| | | Leukemia | Present |
| | | Metastasis | Usually present |
| | | Schwannoma | Present |
| | | Pituitary macroadenoma | Present |
| | | Cavernous sinus meningioma | Present |
| | | Craniopharyngioma | Variable |
| | | Traumatic | Usually none |
| | | Vascular: | |
| | | Ischemia | Variable |
| | | Aneurysm | Enhancement of the aneurysm only |
| | | Pituitary gland apoplexy | Usually none |
| | | Other: | |
| | | Ophthalmoplegic migraine | Present |