From the Guidelines
Diagnosing lower brachial plexopathy associated with herpes simplex virus requires a comprehensive approach combining clinical examination, imaging, and laboratory testing, with the most recent guidelines from 2021 (1) emphasizing the importance of early diagnosis and treatment to prevent permanent neurological damage. The diagnosis should begin with a thorough neurological examination focusing on muscle weakness in the C8-T1 distribution (affecting the hand intrinsic muscles, wrist and finger flexors), sensory deficits along the medial forearm and hand, and possible Horner's syndrome.
- Electromyography (EMG) and nerve conduction studies are essential to confirm the plexopathy and determine its severity and distribution, as recommended by the American College of Radiology (1).
- MRI of the brachial plexus with contrast should be performed to visualize inflammation, compression, or structural abnormalities, with the 2021 update (1) highlighting the importance of imaging in the evaluation of brachial plexopathy.
- For herpes simplex virus confirmation, cerebrospinal fluid analysis for HSV PCR and antibodies is recommended, along with serum antibody testing, as suggested by the management guidelines for suspected viral encephalitis (1).
- Skin lesions, if present, should be swabbed for viral PCR testing. Treatment typically involves antiviral therapy with acyclovir 10 mg/kg IV every 8 hours for 14-21 days, or oral valacyclovir 1 gram three times daily if less severe, with pain management often requiring a multimodal approach with gabapentin (starting at 300 mg daily and titrating up), pregabalin, or amitriptyline, combined with physical therapy to prevent contractures and maintain range of motion, as recommended by the guidelines (1).
- Early diagnosis and treatment are crucial as herpes-related plexopathy can cause permanent neurological damage if left untreated, with the virus directly damaging nerve tissue through inflammatory and cytopathic effects, emphasizing the need for prompt and effective management (1).
From the Research
Diagnosis of Lower Brachial Plexopathy Herpes Simplex
- The diagnosis of brachial plexopathy, including lower brachial plexopathy due to herpes simplex, can be challenging due to non-specific clinical features and similar presentations to other root, nerve, and non-neurologic disorders 2.
- Various diagnostic tests, including electrodiagnostic (EDX) studies, neuroimaging (including ultrasound, MRI, or PET), serologic studies, and genetic testing, may be used to confirm a plexopathy and assist in identifying the underlying etiology 2.
- EDX testing plays an important role in confirming a plexopathy, defining the localization, pathophysiology, chronicity, severity, and prognosis 2.
- Brachial plexopathies can be caused by various factors, including idiopathic neuralgic amyotrophy, which may be more common than previously thought, and herpes zoster infection 3, 4, 5, 6.
- Herpes zoster infection can cause brachial plexopathy, although it is a rare complication, and the mechanism of zoster paresis is still unclear 4, 5, 6.
- Treatment of brachial plexopathy due to herpes zoster infection may include antiviral medications, corticosteroids, and intravenous immunoglobulin, and early diagnosis and treatment can improve outcomes 4, 5, 6.
Diagnostic Approaches
- Electrodiagnostic (EDX) studies, including nerve conduction studies and electromyography, can help diagnose brachial plexopathy and determine the extent of nerve damage 2, 6.
- Neuroimaging studies, such as MRI and ultrasound, can help visualize the brachial plexus and detect any abnormalities or lesions 5, 6.
- Serologic studies can help diagnose herpes zoster infection and other underlying causes of brachial plexopathy 6.
Treatment Options
- Antiviral medications, such as acyclovir and valacyclovir, can help treat herpes zoster infection and reduce the risk of complications 4, 6.
- Corticosteroids, such as methylprednisolone, can help reduce inflammation and relieve symptoms of brachial plexopathy 5, 6.
- Intravenous immunoglobulin can be effective in treating brachial plexopathy due to herpes zoster infection, especially if standard treatment fails 6.