Neuronal Intranuclear Inclusion Disease Mimicking Chronic Inflammatory Demyelinating Polyradiculoneuropathy: A Case Report

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an inflammatory neuropathy, characterized by a slowly progressive onset and symmetrical, sensorimotor involvement. Several diseases, nevertheless, may present similar features as CIDP. It is of paramount importance to recognize these mimics to yield an optimal therapeutic effect. Neuronal intranuclear inclusion disease (NIID) is a rare, progressive neurodegenerative disorder known for its diverse clinical manifestations. Since it may present as sporadic as well as inherited manner and may only involve the peripheral nerve system, it might resemble the clinical course of CIDP. Here, we report the case of a 61-year-old male who presented with subacute onset progressive paresthesia and weakness in lower extremities associated with gait disturbance. Nerve conduction studies demonstrated the features of demyelinating polyneuropathy with predominantly motor involvement. Under the impression of CIDP, immunomodulating therapy was given but with limited clinical response, prompting our consideration of seeking other diseases. Guided by characteristic magnetic resonance image findings during the second round survey, a diagnosis of NIID was confirmed by tissue and molecular pathologies. This is the first report in Taiwan to describe a patient with NIID who initially presented with clinical, electrophysiological, and laboratory features of CIDP, yet later confirmed to be NIID by tissue and molecular proof. Clinicians need to be aware of the possibility of NIID when diagnosing CIPD, especially if atypical presentation such as multi-system involvement or poor therapeutic responsiveness is present.