Spinal myoclonus post-CRT-D implantation: a rare case report of iodinated contrast neurotoxicity

Contrast-induced neurotoxicity (CIN) is a rare complication of iodinated contrast agents, with spinal myoclonus representing an exceptionally uncommon manifestation (<0.01%). To date, no cases have been reported following cardiac resynchronization therapy with defibrillator (CRT-D) implantation.

A 65-year-old man with advanced heart failure (LVEF 28%, NYHA III, QRS 162 ms) underwent successful CRT-D implantation using 50 mL of iopamidol. Four hours post-procedure, he developed sudden, generalized, stimulus-sensitive spinal myoclonus with preserved consciousness. Electroencephalography was normal. Brain and cervical-thoracic spinal MRI on day 3 showed no ischaemic, haemorrhagic, or inflammatory lesions. Serum creatinine remained stable. Intravenous hydration and clonazepam resulted in complete resolution within 72 h, with no neurological sequelae at three-month follow-up (NYHA II, LVEF 38%).

This represents the first documented case of iodinated contrast-induced spinal myoclonus following CRT-D implantation, occurring with the lowest reported contrast volume (50 mL) and preserved renal function. Normal neuroimaging and rapid reversibility under supportive therapy confirm a functional, non-structural mechanism. This case expands the spectrum of CIN in device-based heart failure therapy and emphasizes the need for heightened clinical awareness during coronary sinus cannulation, even in low-risk patients. Early recognition and simple supportive measures ensure excellent outcomes.