Reversible dysphagia due to gabapentin-induced jaw myoclonus
Dysphagia—difficulty swallowing—is a common and scary issue for older adults, often tied to serious conditions like stroke or delirium. But what if the cause is something unexpected: a side effect of a widely used medication? A 2019 study from Queen Mary Hospital, part of the University of Hong Kong, shines a light on a rare but reversible case of dysphagia driven by jaw twitching (myoclonus) linked to gabapentin, a drug prescribed for nerve pain.
Led by Chun-Him Hui, Jackson Ka-Chun Leung, Richard Shek-Kwan Chang, and Yat-Fung Shea from the University of Hong Kong’s Department of Medicine, the study details an 89-year-old woman admitted with three days of inability to swallow liquids and nonstop lower jaw twitching. She had a history of hypertension, diabetes, a healed arm fracture, and postherpetic neuralgia (shingles-related nerve pain) in her right C5 area—for which she’d been taking gabapentin. Her dose was increased to 300 mg three times daily (TDS) two months before her symptoms started.
Doctors ran tests to rule out common culprits: her brain CT was normal, there was no sign of seizures on an EEG, and blood work (including electrolytes, kidney, and liver function) was unremarkable. She was fully alert, with no twitching in other limbs. The key clue? Her kidneys were in stage 3 chronic kidney disease (CKD), with an estimated glomerular filtration rate (eGFR) of 36 mL/min using the Cockcroft-Gault equation—a standard tool to measure kidney function from blood creatinine levels. Gabapentin is cleared by the kidneys, so even an adjusted dose can build up in people with reduced kidney function.
When gabapentin was discontinued and replaced with pregabalin (another nerve pain medication) plus a short course of valium (to calm muscle spasms), her jaw twitching stopped within two days. A speech therapist confirmed she could safely eat again, and she quickly resumed a normal diet. A month later, she had no recurrence of twitching.
Myoclonus—sudden, brief muscle jerks—can be caused by brain injury, infections, or medications. For gabapentin, research shows 0.1% to 12.5% of users may develop myoclonus. Using the Naranjo Adverse Drug Reaction Probability Scale (a tool to link symptoms to drugs), the team scored a 6—meaning gabapentin was the “probable” cause. Most gabapentin-induced myoclonus affects multiple limbs, but this case was unusual: the twitching was isolated to the jaw, directly making it hard to swallow.
Dysphagia in older adults is often linked to life-threatening issues like stroke, but this case highlights a rare, reversible cause. The takeaway for doctors? Always check for medication side effects—especially in patients with kidney disease, since drugs like gabapentin can accumulate even at “adjusted” doses. For patients, it’s a reminder that unexpected symptoms (like jaw twitching or trouble swallowing) should prompt a review of current medications.
This study was published in the Chinese Medical Journal in 2019. The authors report no conflicts of interest.
doi: 10.1097/CM9.0000000000000271
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