Viral mononeurities causing partial oculomotor nerve palsy in an 8 month old child.

BACKGROUND: Palsy of the oculomotor nerve is rarely seen in children, and comprehensive guidelines for management and outcome are difficult to find. CASE: Here we describe a 8 month old boy with left sided ptosis and infero-leteral deviation of left eye and normally reacting pupil and CSF antimeasles antibody titre negative. OUTCOME: The ptosis improved within 3 weeks with no residual neurodeficit. MESSAGE: Viral mononeuritis leading to partial 3rd nerve palsy is a rare entity in children till date.

Introduction

Clinical findings of acquired third nerve palsy depend on the affected area of the oculomotor nerve track. It can be divided into partial or complete palsy.

Partial 3rd nerve palsy are more common, and presents with a variable duction limitation of the affected extraocular muscles and with variable degree of ptosis and/or pupil dysfunction.

Among the various etiology of partial oculomotor nerve palsy in children, viral being the most common, having a self limiting course and good prognosis. We here describe an 8 month old child having partial viral mononeurities of oculomotor nerve, presented with left sided ptosis and down and outward deviation of the eyeball with normally reacting pupil, resolved spontaneously, a rare entity.

Case

An 8-month-old boy presented with fever for 9 days and left-sided ptosis from the very 1st day of fever. The fever was moderate grade and intermittent in nature. It was not associated with any rash, joint pain, convulsion, altered sensorium, or any neurodeficit. The child was otherwise playful. On examination, there was left-sided ptosis with eyeball deviated down and out [Figures 1 and 2]. Pupillary reflex was normal. There was inability to lift the left eyelid. No neurodeficit, with normal tone, power, and reflexes in all the four limbs. Investigations show complete blood count, electrolytes, urea, and creatinine within normal limit.

Figure 1

Left-sided ptosis

Figure 2

Deviation of left eyeball with slightly improved ptosis after 7 days

ANA, ASO titer, pANCA, and cANCA all within normal limit. Magnetic resonance imaging (MRI) of the brain and both orbits along with MRI angio was normal. Cerebrospinal fluid (CSF) study showed lymphocytic pleocytosis with 10 cells/HPF, with normal protein and sugar. IgM and IgG antimeasles antibody in CSF were within normal titer. With supportive management, the child improved. Ptosis and eye deviation resolved almost within 2 weeks [Figure 3] and completely after 3 weeks with no steroids given [Figure 4].

Figure 3

Improvement after 2 weeks follow-up

Figure 4

Complete improvement after 3 weeks

Palsy of the oculomotor nerve is rarely seen in children, and comprehensive guidelines for management and outcome are difficult to find.[12] In a series of 28 children reported by Keith.,[3] CN-III palsy was most often due to trauma, infection, and idiopathic causes, and in a series of 30 children studied by Miller,[4] CN-III palsy was most often congenital or due to traumatic or inflammatory causes. In a study by Schumacher-Feero et al. of the patients with partial CN-III palsy, 47% did not require any alignment surgery because of spontaneous resolution or partial recovery.[5] The association of pediatric oculomotor nerve palsy with inflammatory diseases is well established. It may occur as a part of autoimmune mononeuropathy[6] as a part of ophthalmoplegic migraine,[6] or following antecedent viral infection in the evolution to diffuse ophthalmoplegia in the setting of Miller–Fisher syndrome. Hence, among the causes of ptosis in children, one is infection which may be of viral origin as in our case. Postviral oculomotor nerve palsy is reported in children following measles[7] and norovirus[8] infection. In our case, all autoimmune markers were negative, and CSF measles antibody titer was within normal range. CSF norovirus polymerase chain reaction could not be done due to financial constraints. Transient unilateral third nerve palsy is associated with endoscopic third ventriculostomy and pseudotumor cerebri.[9] Third nerve palsy also has been reported in childhood tubercular meningitis. Here, CSF picture showed only lymphocytic pleocytosis. It has been well established now that oculomotor nerve palsy in children is frequently associated with aneurysm of internal carotid artery and posterior communicating artery.[10] In our case, MRI of the brain along with angiography was normal ruling out all the above possibilities. Thus, having similarity with viral etiology, by the presence of fever and self-limiting course and CSF showing aseptic meningitis, our case becomes a unique one showing unilateral partial third nerve palsy due to viral mononeuritis which is very rare and showed complete recovery without any deficit.

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Conflicts of interest

There are no conflicts of interest.