Delayed Diagnosis of Herpes Zoster Infection due toLong-Term Pregabalin Treatment for Lumbar Spinal Canal Stenosis: A Case Report

INTRODUCTION: Lumbar spinal stenosis is a common disease among elderly adults, and pregabalin is increasingly used for pain relief in this disease. However, little is known about whether pregabalin may cause any undesirable outcomes when used conjointly with other medications in elderly people. We report a case of herpes zoster infection, the initial symptom of which was obscured due to the use of a combination of pregabalin, tramadol, and acetaminophen for lumbar spinal canal stenosis. CASE REPORT: In February 2018, a 72-year-old Japanese man presented with eruption without pain on his right shoulder. As an itching sensation and pain gradually emerged, he visited the clinic10days after the initial appearance of the eruption. He was diagnosed with lumbar spinal canal stenosis, in 2014, and had been prescribed a combination of tramadol, acetaminophen, and pregabalin for pain relief. He was diagnosed with herpes zoster infection, and valacyclovir was prescribed for 7 days. His symptoms were relieved on the 10thdayafter the initial presentation. CONCLUSION: The use of multiple analgesic agents, including pregabalin, may conceal pain associated with herpes zoster infection and delay its early diagnosis, possibly leading to a worse outcome of the disorder.