Reversible myoclonus, asterixis, and tremor associated with high dose trimethoprim-sulfamethoxazole: a case report

Reversible myoclonus, tremor, and asterixis induced by high dose trimethoprim-sulfamethoxazole.

The patient was a 66-year-old male with T9 AIS(1) C quadriplegia secondary to spinal cord compression by a tumor due to large B cell lymphoma. Subsequent to tumor resection and chemotherapy, the patient was discovered to have Pneumocystis jiroveci pneumonia (PJP). Once started on high dose trimethoprim-sulfamethoxazole (TMP-SMX) therapy (15.6 mg/kg/day of trimethoprim) for the treatment of PJP, he displayed bilateral upper extremity myoclonic jerks at rest, asterixis, and postural tremor. Symptoms resolved once TMP-SMX therapy was discontinued.

Myoclonus, asterixis, and tremor have been linked to high dose TMP-SMX therapy as a toxic side effect. Our patient's symptoms did improve with levetiracetam therapy, but did not fully resolve until TMP-SMX was discontinued.

This is thought to be the first reported case of reversible myoclonus, tremor, and asterixis induced by high dose TMP-SMX in the spinal cord injury population. Early recognition of TMP-SMX induced complications were of key importance as they negatively impacted the rehabilitation process. We also recommend consideration of symptomatic treatment with levetiracetam for the duration of required TMP-SMX therapy as it appeared to mitigate the severity of our patient's movement disorders.