A case of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) associated with acute bilateral optic neuritis with normal findings on pattern-reversal visual evoked potential study

Abstract

A 35-year-old man with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) associated with acute bilateral optic neuritis is described. At age 33, he noticed a tingling sensation in his toes followed by weakness in the lower limbs. He was admitted to our hospital because he became unable to walk without support. His motor and sensory symptoms gradually resolved during 7 months admission only with physical rehabilitation. At age 35, in July 1988, he noticed a tingling sensation in his toes and fingers, which reached to the knees and elbows in October 1988, when he developed weakness in the lower limbs. Motor and sensory symptoms were almost stationary thereafter and in March l989, he experienced bilateral blurred vision of acute onset without ocular pain. He was readmitted to our hospital in April 1989. The neurological examination revealed decreased visual acuity of both eyes without any abnormality of the optic disks, mild weakness on flexion and extension of toes, an absence of Achilles reflex, and distal impairment of pain and touch sensations in the upper limbs, and of pain, touch and vibration sensations in the lower limbs. After laboratory examinations, CSF protein was elevated (122 mg/dl), and sensory nerve conduction velocity of the right median nerve was decreased (37.1 m/sec). The sural nerve action potential was not elicited on electrical stimulation. Central scotoma was found in both eyes by the visual field examination. P100 latency was seen to be normal by repeated pattern-reversal visual evoked potential (VEP) studies. CT and MRI of the brain were unremarkable. On sural nerve biopsy, axonal degeneration and segmental demyelination with a moderate decrease in the density of the myelinated fibers and onion-bulb formation at low frequency were found. After two months treatment with prednisolone (40 to 60 mg on alternate days), visual acuity was markedly improved and central scotoma disappeared. Motor and sensory symptoms in both limbs were also improved. CSF protein was normalized and sensory nerve conduction velocity of the right median nerve was definitely improved. In this patient, pattern-reversal VEP studies were normal and failed to support the presenee of demyelinating lesions in the visual pathway, which was strongly suggested hy the neurologic findings. However, steroid treatment resulted in a marked improvement of neurologic symptoms and signs, including visual acuity and lahoratory findings. Therefore, we concluded optic neuritis was one of the signs of CIDP in this patient.