Description of Event or Problem · 1
JOURNAL REF: DALTON C, KEENAN E, STEVENSON V. A NOVEL CAUSE OF INTRATHECAL BACLOFEN OVERDOSAGE: LESSONS TO BE LEARNT. CLIN REHABIL. 2008;22(2): 188-190. THIS ARTICLE REPORTS ON AN INTRATHECAL BACLOFEN OVERDOSE IN A FEMALE WITH PRIMARY PROGRESSIVE MULTIPLE SCLEROSIS FOLLOWING A CATHETER DYE STUDY AND CONCOMITANT CHANGE IN BACLOFEN CONCENTRATION. HER PUMP HAD BEEN PLACED ABOUT 3 MONTHS EARLIER WITH GOOD CONTROL OF LOWER LIMB SPASTICITY. AT THE FIRST REFILL, ABOUT 3 WEEKS EARLIER, THE CONCENTRATION WAS CHANGED FROM 1000 MCG/ML TO 2000 MCG/ML TO DECREASE REFILL FREQUENCY. ABOUT THIS TIME HER LOWER LIMB SPASTICITY AND PAIN WORSENED. AN ABDOMINAL X-RAY INDICATED INTRATHECAL PUMP CATHETER DISLODGEMENT; HOWEVER, A REPEAT X-RAY DID NOT CONFIRM DISLODGEMENT. A DYE STUDY WAS DONE DURING WHICH THE PUMP WAS STOPPED AND EMPTIED, AND AN EXTRA 1 ML FLUID WAS REMOVED USING THE CATHETER ACCESS PORT. THIS FLUID WAS CHECKED FOR GLUCOSE, CONFIRMING THE PRESENCE OF CEREBROSPINAL FLUID. OMNIPAQUE 240 (6 ML) WAS INJECTED; THE CATHETER TIP WAS WITHIN THE SPINAL SUBARACHNOID SPACE. DUE TO HER WORSENING OF SPASTICITY AFTER THE FIRST REFILL, IT WAS DECIDED TO EMPTY AND REFILL THE PUMP WITH FRESH BACLOFEN. THE BACLOFEN CONCENTRATION WAS CHANGED FROM 2000 MCG/ML TO 1000 MG/M, AND THE PUMP WAS REPROGRAMMED AT THE SAME DOSE (139.8 MCG/24 HRS). A PRIMING DOSE WAS CALCULATED THAT ACCOMMODATED THE VOLUME OF THE EMPTY CATHETER BUT NOT THE VOLUME OF DRUG REMAINING IN THE INTERNAL PUMP TUBING, WHICH CONTAINED BACLOFEN 2000 MCG/ML. TWO HRS AFTER THE REFILL PROCEDURE, THE PT DEVELOPED SYMPTOMS OF OVERDOSE. THE PUMP DOSE WAS DECREASED TO 60 MCG/24 HRS. THE PT WAS TRANSFERRED TO INTENSIVE CARE, INTUBATED, AND VENTILATED DUE TO APNEIC EPISODES. SHE WAS WEANED OFF THE VENTILATOR OVER THE NEXT 48 HRS AND TRANSFERRED BACK TO THE REHABILITATION WARD.