Physician Montefiore Medical Center Bronx, New York, United States
Case Diagnosis: Brachial plexitis
Case Description: 60-year-old male with a past medical history of diabetes mellitus and renal transplant (therefore immunosuppressed) was diagnosed with shingles on left posterior arm and left thumb and treated with valacyclovir. Soon after, he developed severe left upper extremity (LUE) pain, which was managed with gabapentin. After four months, he developed LUE numbness and weakness. On examination, he had atrophy of his left deltoid, biceps, triceps, shoulder girdle and intrinsic hand muscles, a left wrist and finger drop, a positive Forment’s sign, and a resting tremor. Sensation to light touch was symmetrical except in the left forearm. EMG showed abnormal sensory nerve conduction study (NCS) in the left antebrachial cutaneous, radial and median nerves, abnormal motor NCS in the left median and ulnar nerve with axonal loss and fibrillations in multiple LUE muscles. Consequently, he was diagnosed with left brachial plexopathy.
Discussions: Herpes zoster virus (HZV) can cause shingles, a unilateral painful vesicular eruption within a dermatome. It often presents in adults over 50 or in immunocompromised individuals, with an incidence of 125/100,000. Shingles results from reactivation of latent HZV within the dorsal root ganglion and its axoplasmic transport to nerve terminals which causes the segmental cutaneous rash and neuralgic pain. Complications include post-herpetic neuralgia, meningoencephalitis, transverse myelitis, vision loss, cranial nerve palsies and deafness. Motor paresis seen with HZV is likely due to both proximal and distal spread of the virus to the spinal nerve/ventral root. While mononeuropathy may be seen with HZV, polyradiculopathy is rare.
Conclusions: Though rare, clinicians should consider HZV radiculopathy in immunosuppressed patients with motor weakness following a cutaneous HZV infection. Treatment is conservative and includes pain control and physiotherapeutic rehabilitation.