The association of pediatric third nerve palsy with inflammatory disease is now well established. It may occur as a painless autoimmune mononeuropathy,189 as part of the spectrum of ophthalmoplegic migraine, or following antecedent viral infection in the evolution to diffuse ophthalmoplegia in the setting of Miller Fisher syndrome.616 Some of these cases may represent postviral oculomotor palsy (see below).

Neoplastic Causes of Third Nerve Palsy

in Children

A variety of neoplasms have been reported to cause childhood oculomotor palsy, involving the nerve along its subarachnoid, intracavernous, or orbital portion.

360,404,471,496,542,607

Causative tumors have included astrocytoma, sarcoma, lymphoma, meningioma, schwannoma, neuroepithelial cyst, pituitary adenoma, craniopharyngioma, epidermoid, dermoid cyst, arachnoid cyst, endodermal cyst, malignant peripheral nerve sheath tumor, teratoid tumor, and cavernous hemangioma.481 Among acquired pupil-involving oculomotor nerve palsies in children, 10% are estimated to be due to neoplasm.368,398

Schwannomas are now detected more commonly using high-resolution MR imaging in children with oculomotor nerve palsies using serial gadolinium-enhanced 1–2 mm thin-section MR imaging with coronal views.398,403 Norman et al described five children with isolated monocular oculomotor palsy originally believed to be idiopathic but subsequently documented to be secondary to a presumed neuroma (schwannoma) of the intracranial oculomotor nerve distal to the mesencephalon.403 In these patients, the oculomotor findings progressed, and no signs of aberrant regeneration were noted. Less commonly, neurofibromas in the cavernous sinus,97 and malignant peripheral nerve sheath tumors of the oculomotor nerve have been found.297 Neural grafting procedures have been used to partially restore oculomotor function.178,344

Postviral Third Nerve Palsy

Postviral oculomotor palsy have been reported in children following measles90 and norovirus infection.307

Oculomotor palsy occasionally develops in children with collagen vascular diseases. Kirkali et al282 described oculomotor palsies in two children with polyarteritis nodosa that resolved following treatment with cyclophosphamide. Transient unilateral oculomotor nerve palsy has been reported following endoscopic third ventriculostomy,430 and transient unilateral and bilateral oculomotor palsy has been reported in a child with pseudotumor cerebri.98,547 Third and sixth nerve palsies have been reported in patients with pediatric tubercular meningitis.13 One transient oculomotor palsy developed in conjunction with benign recurrent sixth nerve palsy.226

Differential Diagnosis

The differential diagnosis of third nerve palsy in childhood is summarized in Table 6.2. MR imaging has become an informative part of the routine diagnostic evaluation in pediatric oculomotor palsy. High-resolution intracranial and orbital MR imaging can demonstrate absence or hypoplasia of the involved oculomotor nerve, as well as hypoplasia of the extraocular muscles and correlative torsion causing a change in orbital extraocular muscle position in the coronal plane.136,606 In many cases, high-resolution MR imaging shows a reduction of volume and contractility of the involved extraocular muscles.262

The diagnosis of myasthenia gravis should be considered in the child with a painless, pupil-sparing third nerve palsy and no aberrant regeneration (especially when there is prominent inferior rectus or medial rectus weakness).47 Aberrant regeneration is commonly seen in congenital or acquired third nerve palsies but is never a feature of myasthenia gravis. The improvement of ptosis immediately upon awakening and a history of fluctuating or ophthalmologic or systemic symptoms (breathing difficulty, choking, drooling, facial palsy) warrant a prostigmine test and an antiacetylcholine receptor antibody test.

Congenital fibrosis of the extraocular muscles (CFEOM) is an autosomal dominant disorder characterized by diffuse

Table 6.2  Differential diagnostic considerations of third nerve palsy in childhood

Myasthenia gravis

Blowout fracture

Congenital fibrosis syndrome

Internuclear ophthalmoplegia

Duane syndrome (Type II)