Can we use Tramadol as an anti-shivering agent?

Sir,

Tramadol seems to have the best combination of anti-shivering and analgesic efficacy without causing too much sedation in the post-operative period. Seizures have been reported in patients receiving the drug in overdose and, rarely, at the recommended dose unless it is taken by the patients with history of epilepsy or taken with other drugs that reduce seizure threshold.[1]

We report a case of a 45-year-old, ASA Grade I, female patient, weighing 52 kg electively posted for vaginal hysterectomy. The patient had no family history of epilepsy and was not on any other medication.

Subarachnoid anaesthesia was instituted at the L3-4 interspace using hyperbaric 0.5% Bupivacaine. Towards the end of the procedure, the patient complained of shivering, and intravenous Tramadol 100 mg was administered slowly over 2–3 min. After 2 min, the patient had generalized tonic-clonic seizures. The patient was given 100% oxygenation using Bain's circuit, and intravenous Midazolam 2 mg was administered. The convulsions subsided. The patient was awake but confused and disoriented. She got better after 30 min. Other neurological examinations were normal. Serum electrolytes, blood sugar and computed tomography of the brain were normal. The patient was followed-up for the next 15 days, and there was no recurrence of seizure.

After searching the literature, we found few Tramadol- induced seizure reports at therapeutic doses in non operative setting.

Talaie and others concluded in their study that Tramadol intake does not differ between patients with and without seizures, and the most common dose range in those with seizures is 500–1000 mg, with the incidence of seizure with Tramadol not being dose-dependent.[2]

Jick et al. found that there was no increased risk of idiopathic incident seizures associated with exposure to Tramadol alone. The seizures seem rarely attributable to the agent.[3]

Gasse et al. also suggested that the risk of idiopathic seizures was elevated in each analgesic exposure category compared with non-users, suggesting that the risk for patients taking Tramadol was not increased compared with other analgesics.[4]

Massoud Mehrpour reported two cases of intravenous Tramadol-induced seizure at therapeutic doses prescribed for headache, and opined that Tramadol can induce seizure and even status epilepticus, especially in intravenous prescription, which could be due to serotonergic effects.[5]

In our case, administration of other epileptogenic drugs was ruled out and we ruled out all possible secondary causes like electrolyte imbalance, undiagnosed cerebral pathology, hypoglycemia etc.

In conclusion, though intravenous Tramadol, in therapeutic doses, has proven antishivering as well as analgesic actions in the peri operative setting, utmost caution should be exercised while using the drug.