822 - Atypical Coexistence: Postherpetic Neuralgia and Brachial Plexitis in a 70-year-old Male

Case Diagnosis: Concurrent Postherpetic Neuralgia (PHN) and Brachial Plexitis.

Case Description: A 70-year-old male with a history of CLL, CVID, Hypothyroidism, and herpes zoster presented with severe left arm pain, allodynia, hyperalgesia, and weakness in the ulnar distribution. Initial investigations suggested PHN, but persisting motor deficits signaled an atypical scenario. A subsequent ganglion block (SGB) provided no relief. An MRI of the C-spine revealed multilevel degenerative disc disease but did not offer an anatomical explanation for the symptoms. An EMG study suggested axon-loss pathology involving C8 >T1 innervated muscles which confirmed brachial plexitis, revealing a rare combination of disorders.

Discussions: The coexistence of PHN and brachial plexitis in the same patient poses a unique diagnostic and therapeutic challenge. While PHN is a relatively common aftermath of herpes zoster, its convergence with brachial plexitis is scarcely documented in literature. The patient's non-response to the stellate ganglion block was an indicator of the underlying complex pathology, emphasizing the importance of a multifaceted diagnostic approach. The decision to proceed with ESI was based on earlier MRI findings, underscoring the necessity of correlating clinical findings with diagnostic tools. Moreover, introducing icosapent ethyl (Vascepa) in the patient's regimen, given its known anti-inflammatory benefits in neuropathic conditions, highlights the value of a personalized therapeutic approach.

Conclusions: The simultaneous presentation of PHN and Brachial Plexitis offers a unique diagnostic challenge. Treatment strategies must be comprehensive, considering the overlapping symptomatology and potential for atypical presentations. This case underscores the importance of nuanced clinical evaluation, especially in atypical presentations, guiding therapeutic decision-making.