Third CN palsy and underlying lesions

Anatomic Site	3. CN Dysfunction Features	Associated Clinical Findings	Etiologies	Contrast Enhancement of 3.CN or Its Nuclei
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:
Subarachnoid space	Complete or incomplete (divisional) paresis	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