Abstract
Introduction
Classic chronic inflammatory demyelinating polyneuropathy (CIDP), an acquired demyelination of peripheral nerves and nerve roots presents with symmetric motor and sensory involvement, weakness in proximal and distal muscles, globally diminished or absent reflexes, painful dysesthesias, and back pain with no brain involvement. In this case, a highly functional lawyer presents with reversible dementia and motor and sensory symptoms consistent with CIDP. This case may represent a new clinical entity of CIDP with reversible dementia.
Case Report
A 60-year-old man presented with progressive weakness, and cognitive dysfunction in the form of dementia over the last 8 weeks. Sensory and motor weakness continued to progress affecting upper and lower extremities with both proximal and distal muscle groups to the point where the patient was unable to move without assistance. The patient had word finding difficulty, short-term memory impairment, and was disoriented, despite his comprehension being intact. Initial Montreal Cognitive Assessment (MoCA) was 12/30. Initial neurologic exam was notable for muscle strength 3/5, globally depressed deep tendon reflexes. Lumbar puncture revealed elevated protein with no pleocytosis and no serum paraprotein. EMG/NCS demonstrated mixed sensorimotor axonal and demyelination peripheral polyneuropathy. CIDP was diagnosed based on clinical history according to Koski criteria. He was started on a 5-day treatment of IVIG, after which he had marked cognitive improvement after just one dose and improvement in weakness after the second dose of IVIG. Three weeks after IVIG treatment, the patient's cognitive function was back at baseline with MoCA score 29/30; no further word finding difficulty, and no short term memory impairment. At discharge, the patient's weakness had significantly improved to the point where he was able to walk with only the aid of a walker. His neurologic exam had improved as well as his muscle strength 4/5 and 2/4 deep tendon reflexes. Left sural nerve biopsy would eventually reveal moderate peripheral neuropathy with axonal degeneration, moderate loss of large and small myelinated nerve fibers, confirming diagnosis of CIDP.
Discussion
CIDP encompasses several different variants, including Lewis-Sumner syndrome, distal acquired demyelinating sensory neuropathy, sensory predominant CIDP among other variants. However, none of the variations of CIDP have a reversible cognitive impairment component. Patient met diagnosis of CIDP according to Koski criteria, as he had chronic polyneuropathy progressive for at least 8 weeks with no serum paraprotein, no genetic abnormality, and symmetric exam revealing weakness in all four limbs and proximal weakness in both lower extremities. Potentially, the patient could have had simultaneous diagnosis of dementia and CIDP, but the marked improvement in cognitive function after just one dose of IVIG makes that theory unlikely. PubMed search yielded no single case of CIDP with supratentorial manifestations in a patient with normal brain MRI. This case may represent a new clinical variant: CIDP with cognitive impairment.
Conflict of Interest
The authors report no conflict of interest.