Internuclear Ophthalmoplegia

Abstract

nternuclear ophthalmoplegia (INO) is a sign of exquisite localizing value, often due to either multiple sclerosis or infarction. To demonstrate that unusual causes of INO are more common than the 11% reported in previous series, this review considers a case series of 410 inpatients whom I personally examined during a 33-year period. In this series, the cause of INO was infarction in 157 patients (38%), multiple sclerosis in 139 (34%), and unusual causes in 114 (28%). Unusual causes included trauma (20 cases), tentorial herniation (20 cases), infection (17 cases), tumor (17 cases), iatrogenic injury (12 cases), hemorrhage (13 cases), vasculitis (7 cases), and miscellaneous (8 cases). Internuclear ophthalmoplegia was unilateral in 136 of the infarct cases (87%), 38 of those with multiple sclerosis (27%), and 48 of the unusual cases (42%). Because unusual causes compose more than one quarter of the cases, the differential diagnosis of INO should be tripartite: multiple sclerosis, stroke, and other causes.

Bilateral pseudo-internuclear ophthalmoplegia in a patient with myasthenia gravis

“…6 Although the mechanism is unknown, pseudo-INO associated with MG may arise from the combination of: (1) antibody-mediated peripheral disruption of neural signals to the extraocular muscles at the NMJ, producing adduction deficit 5 and (2) central overcompensation for the adduction deficit, producing dissociated contralateral nystagmus. 8 , 11 , 18 …”

“…Patients with bilateral INO display bilateral adduction deficits with contralateral abducting nystagmus. True INO is a sign classically associated with demyelination-induced dysfunction in multiple sclerosis (often bilateral INO) 10 , 11 or with ischemic damage to the MLF (often unilateral INO). 12 However, extraocular muscle weakness can rarely produce a pseudo-INO.…”

Profile of Gaze Dysfunction following Cerebrovascular Accident

“…However, INO may be due to infarction at many levels of the brainstem including caudal and rostral pons, isthmus, and midbrain [25] and is due to interference with interconnections between the sixth nerve nucleus and contralateral medial rectus subnucleus via the medial longitudinal fasciculus [19, 20]. All our cases were unilateral as is usual for INO caused by infarction [26]. …”

Neurocysticercosis presenting as isolated wall-eyed monocular internuclear ophthalmoplegia with contraversive ocular tilt reaction

“…These include vertical diplopia, nystagmus, one and a half syndrome, isolated facial myokymia, bilateral INO, and oculomotor nerve palsy. [3–6] Thus, depending on the location of the lesion, neurocysticerci can have varied manifestations. Other well-known causes of INO include brainstem neoplastic lesions, myasthenia gravis, Arnold-Chiari malformation, nutritional and metabolic encephalopathies.…”