Isolated Ulnar Neuropathy After Acute Angioedema

Ulnar neuropathy commonly causes hand paresthesia, often associated with mechanical compression or repetitive movements across the elbow or wrist. There are a few cases that document ulnar nerve injury from rapid compression in the absence of trauma. We present a 30-year-old previously healthy male who developed bilateral hand and forearm swelling, numbness, and pain after an allergic reaction initially treated with epinephrine and steroids. Following treatment, swelling improved; however, paresthesia and weakness persisted. Electrodiagnostic studies performed two months later showed severe ulnar neuropathy prominent at the left proximal wrist, confirmed by ulnar motor inching studies. Signs of acute or subacute denervation and active reinnervation were noted in the left flexor digitorum profundus and abductor digiti minimi. Right-sided studies were unrevealing, although magnetic resonance imaging (MRI) showed an acute flexor pollicis longus tear. Given the timing of events, it was felt that the ulnar neuropathy and acute muscle tear were related to the rapid onset of angioedema. Further research should be conducted on how acute episodes of angioedema (allergy) can cause nerve compression in different extremities. There are very scant reports of different types of angioedema (such as vibratory or hereditary) associated with neuropathy; however, there are no reports of acute allergic angioedema associated with neuropathy. A more comprehensive understanding of the pathophysiology of neuropathy following acute angioedema will help guide treatment approaches both acutely and after symptom presentation.