NEU

ROLO

GY

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SYMPTOMS

In addition to focal abnormalities, patients often suffer from chronic fatigue.Symptoms are exacerbated by heat and exercise (the Uhthoff phenomenon);old deficits are also worsened by underlying illness, especially infections suchas UTIs or URIs.

EXAM

Classic lesions and exam findings include the following:

■ Optic nerve: Optic neuritis presents as unilateral subacute vision loss as-sociated with pain on eye movement. Exam shows pallor of the opticnerve, decreased visual acuity, difficulty with color discrimination, and arelative afferent pupillary defect (RAPD, or Marcus Gunn pupil) (seeFigure 13-2).

■ Brain stem: A demyelinating lesion of the medial longitudinal fasciculus(MLF) that yields an internuclear ophthalmoplegia (INO). Patients com-plain of double vision when looking to one side; exam reveals inability toadduct the eye ipsilateral to the lesion when looking to the contralateral

F I G U R E 1 3 - 2 . Afferent pupillary defect (Marcus Gunn pupil).

(Reproduced, with permission, from Riordan-Eva P. Vaughan & Asbury’s General Ophthalmol-ogy, 16th ed. New York: McGraw-Hill, 2004, Figure 14-32.)

Diffuse illumination

Light on normal eye

Light on eye with afferent defect

Normal reaction of both pupils

Decreased reaction of both pupils

5 mm 5 mm

2 mm 2 mm

4 mm 4 mm

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