This case is meant to explore some of the mechanisms of the development of motor paresis following herpes zoster infection known as HCV. The characteristic painful sensory changes following HCV are well-known and recognized. It is also possible to develop subsequent motor paresis, which is a rare and under-recognized complication without a fully agreed upon mechanism. This poster reviews the case of a 60-year-old female who presented with right upper extremity pain followed by the development of a characteristic shingles rash in the C4 through C5 dermatomes. She subsequently developed acute onset of proximal right upper extremity weakness. She underwent physical therapy and regained near full function three months after initial onset of weakness. Regarding her diagnostic workup, she had a right shoulder MRI and an EMG performed three weeks after initial symptom onset. On MRI, T2 hyperintensity can be seen in the supraspinatus, infraspinatus, and deltoid, which are labeled in Figure 1. On electrodiagnostic evaluation, nerve conduction studies were within normal limits and abnormalities on needle EMG were noted in the deltoid and infraspinatus as outlined in Figure 2. We will now explore the possible diagnoses for this case, which include brachial neuritis, mononeuritis multiplex, and less likely segmental zoster paresis. Brachial neuritis is well recognized as a post-infectious process and has been previously associated with HCV. The patient experienced the classic symptoms of pain followed by weakness, and the MRI findings are consistent with this diagnosis. Now moving on to mononeuritis multiplex. There are case reports describing this as a post-infectious process but not specifically occurring with HCV. In this case, there would be involvement of the axillary and suprascapular nerves. It would be beneficial to assess additional muscles innervated by these nerves on needle EMG. Finally, we will consider segmental zoster paresis. It is estimated to occur in 0.5% to 5% of cases of cutaneous herpes zoster. The pathogenesis is controversial but is believed to be due to direct viral spread of the infection from the dorsal root ganglion to the anterior horn cells, ventral root, or peripheral nerves. There is a close relationship documented between dermatome and myotome involvement in previously published cases. In our case, the patient has involvement of some but not all C5 innervated muscles tested on needle EMG. An important point to consider in this case is the utility of electrodiagnostic testing and prognostication. The minimal amount of denervation and normal recruitment pattern in most muscles was promising. And as we anticipated, this patient made a very good recovery in only a few months. While it remains challenging to definitively diagnose our patient with the data that we have, this case serves as a reminder that HCV can have not only sensory but also motor involvement. I would like to thank Dr. Tim Foster and Dr. Mark Goddard for their assistance with this write-up. Thank you for taking the time to listen, and I hope you found this case to be both interesting and informative.

60-year-old female

motor paresis

herpes zoster infection

complication

diagnostic workup