Chronic Inflammatory Demyelinating Polyneuropathy With Reversible Severe Cognitive Impairment and Gastrointestinal Dysfunction.

We treated a patient with an unusual case of reversible rapidly progressive cognitive impairment, gastrointestinal dysfunction, and generalized neuromyopathy in chronic inflammatory demyelinating polyneuropathy (CIDP) with optic neuropathy. A man in his 50s presented with a four-month history of rapidly progressive cognitive decline in addition to a six-month history of proximal greater than distal painful muscle weakness, wasting in all extremities, almost complete loss of deep tendon reflexes in his lower extremities, and slow progressive vision loss. Additionally, he had a 90-pound weight loss over the past two years with loss of appetite and ongoing chronic diarrhea. The exam showed muscle weakness and wasting with absent deep tendon reflexes. Initial Saint Louis University Mental Status (SLUMS) exam score was 16/30. Visual acuity was 20/25 with full extraocular movements; optical coherence tomography revealed superior arcuate bundle thinning bilaterally. Gastrointestinal workup proved nonrevealing. Serologic studies for vitamin deficiencies, heavy metals, and autoantibodies were negative. Whipple, Giardia lamblia , and Campylobacter jejuni stool testing were negative. Imaging studies were unremarkable. Nerve conduction studies showed demyelinating sensorimotor peripheral neuropathy. Muscle biopsy was indicative of denervation with scattered myopathic changes; no evidence of inflammatory myopathy nor glycogen or mitochondrial abnormalities was seen. Intravenous immunoglobulin treatment was begun. The patient was started at a dose of 0.75g/kg every three weeks. Following good but incomplete clinical improvement after the first treatment, his dose was increased to 1g/kg every three weeks. He improved remarkably after four months of infusions, scoring 30/30 on SLUMS with a full return of muscle strength and reflexes. Diarrhea remitted. Visual acuity and conduction delay remained unchanged. Symptom timing and dramatic response to immunoglobulins suggest a common immunological mechanism. In light of extensive differential investigations, unremarkable imaging and serology, and no other systemic disease processes, this case plausibly represents a potential new CIDP phenotypic variant.