1527 - Acute-onset Distal Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) vs Acute Inflammatory Demyelinating Neuropathy (AIDP)

Case Diagnosis: Acute-onset Distal Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP)

Case Description: A 49-year-old healthy male developed acute onset cervico lumbar pain with dysesthesia in all four extremities, further progressing to right facial weakness and ataxia one week later. No inciting event. During the initial visit, approximately one month from symptom onset, he reported rapid improvement with only mild persistent dysesthesias in the distal upper and lower extremities, asymptomatic proximal to the wrist and upper calf. Physical exam revealed diminished power in left thumb adduction, bilateral plantarflexion and hallux extension. He had a preserved left triceps reflex, otherwise reflexes were absent or diminished. Hyperalgesia was present in the distal extremities bilaterally, as well as loss of vibratory sense. Electrodiagnostic studies revealed markedly prolonged distal latencies with distal temporal dispersion and significant distal conduction slowing. Proximal conduction velocities were normal. Ultrasound revealed diffuse enlargement of peripheral nerves.

Discussions: His presentation is most consistent with acute-onset distal CIDP, supported by distal neuropathic symptoms, exclusively distal electrodiagnostic findings, and diffuse nerve enlargement on ultrasound. While the acute onset and rapid improvement could suggest AIDP, which typically presents with ascending paralysis, the early phase of CIDP may appear similar. Taken together, the clinical, electrodiagnostic, and ultrasound findings favor acute-onset distal CIDP.

Conclusions: Distinguishing between AIDP and CIDP is essential for appropriate management. If this were AIDP, his symptoms would be unlikely to recur, and he would not respond to treatments such as corticosteroids. In contrast, distal CIDP may follow a relapsing-remitting course and may require long-term therapy, including corticosteroids. Although an acute presentation of distal CIDP is uncommon, the combination of his clinical, electrodiagnostic, and sonographic findings strongly supports this diagnosis and has important implications for guiding treatment.