Infectious mononucleosis with cranial nerve palsies.

The neurological complications of infectious mononucleosis may rarely occur in the absence of the classical symptoms and signs of infectious mononucleosis. Widespread involvement of the cranial nerves is very rare. It is important to consider infectious mononucleosis in the differential diagnosis of any young adult presenting with a neurological illness. CASE HISTORY A 19-year-old female student presented with a one-week history of headaches in the left temple, each lasting two hours and preceding a sudden onset of diplopia and left ptosis, which came on while she was photocopying at work. The diplopia deteriorated over the next few days and she developed an aching pain in the jaw. There was a three-day history of difficulty in swallowing and of slurring of speech. In particular, she had difficulty moving food around her mouth. There was no history of weakness in the limbs. She had had a mild irritation of her throat two or three weeks prior to her admission. There was no history of fever. She was well nourished, alert and well orientated. There was no significant enlargement or tenderness of the lymph nodes. She was not icteric. There were no rashes. She was normotensive, in sinus rhythm and had no cardiac murmurs. The chest was clinically clear. Liver and spleen were not palpable. The pupils were normal size and reacted normally to light and accommodation. Visual acuity was 6/6 on both sides. Fields of vision were full. Optic fundi were normal. There was no bilateral ptosis. External ocular movements were restricted on both sides. Depression and adduction were full in both eyes. In the right eye, adduction was reduced to 50% of the full range and elevation to 25 %. In the left eye, elevation was reduced to 50% and adduction to 75%. There was no nystagmus. Corneal reflexes and facial sensation were normal. Jaw jerk was not present. There was no wasting or weakness of the jaw muscles. There was an almost complete bilateral facial palsy. Hearing was not impaired and she could hear a whisper at two feet. Rinnie's and Weber's tests were normal. The soft palate moved normally, and gag reflexes were normal. The sternomastoids and trapezii had full power. The tongue was weak and could not be protruded fully. It