Anesthetic management of a child with Lennox-Gastaut syndrome with intractable epilepsy posted for intracranial surgery!

Dear Sir,

Lennox–Gastaut syndrome (LGS) is childhood epilepsy which is difficult to treat. It usually appears before 8 years of age. LGS is characterized by a triad of multiple types of seizures, moderate to severe cognitive impairment,[1] and an abnormal electroencephalogram (EEG) pattern (<2.5 Hz).[2] Most patients have both tonic and atonic seizures while tonic seizure occurs commonly during sleep. Nearly, all have treatment resistant seizure and about 60% of patients progress to status epilepticus. Uncontrolled seizures are difficult to treat during both induction and emergence. Anesthesiologists must prepare themselves for managing such situation before taking up for surgery since there is high probability of perioperative seizures due to proconvulsive effects of anesthetic drugs due to the interaction between anesthetics and therapeutic drugs. We report a successful anesthetic management of child with LGS.

The patient, a 4-year-old male child weighing 14 kg, was diagnosed as a case of LGS with intractable epilepsy posted for corpus callosotomy surgery under general anesthesia. He was apparently alright till the age of 2 years until he started to have seizure of semiology – epileptic spasm followed by atonic seizure with associated mental and language regression. He was born by normal vaginal delivery at full-term with immediate cry with normal developmental milestones till the age of 2 years. At 2 years, he developed low to moderate fever associated with lethargy and vomiting. After 1 month of this episode, he was noticed to have sudden onset abduction of shoulders with flexion of both arms associated with head flexion. These episodes used to occur in clusters, sometimes 50–60 times/day. It usually consists of head drop either forward or backward lead to injury multiple times [Figure 1]. There were no associated movements in limbs or up rolling of eyeballs or bladder or bowel incontinence. Although he took antiepileptic drugs (AEDs) (valproate, levetiracetam), the tonic/atonic seizures persisted. After 3 months of onset of illness, he developed episodes of abnormal behavior lasting for few minutes. He was noticed to have mental regression and stopped eating. Slowly, there was associated gradual decrease in speech output. He was diagnosed as case of LGS as sequel of viral encephalitis. On magnetic resonance imaging, no structural abnormality detected. His first EEG showed <2.5 Hz slow spiked wave. His video-EEG monitoring revealed a continuous slow interictal activity with asymmetrical progression on left hemisphere. His serum valproate (64.1 mcg/ml) and serum ammonia (49.8 µmol/L) levels were within normal range; the metabolic profile was also found to be normal.

Figure 1

Arrows showing multiple recurrent injuries on head following drop attacks

His preoperative laboratory investigations and vital signs were normal. He received regular AEDs (lamotrigine 25 mg, clobazam 10 mg, and oxcarbazepine 75 mg) in the morning of the surgery. Anesthesia was induced with sevoflurane (6%) with 100% oxygen along with fentanyl 25 mcg. After checking the mask ventilation, rocuronium bromide 10 mg was administered. Trachea was intubated with 4.5 mm polyvinyl chloride endotracheal (microcuff) tube. Anesthesia was maintained with sevoflurane (1–1.5%), nitrous oxide, and oxygen. Intraoperative and postoperative period remained uneventful. His trachea was extubated and he was shifted to Neuro Intensive Care Unit (NICU) for monitoring and further management. He remained seizure-free in postoperative period and shifted to neurosurgical ward after 24 h of monitoring in NICU.

Distinguishing LGS from other childhood epilepsy conditions requires an assessment of clinical as well as EEG features. LGS mainly comprises drop attacks resulting in multiple recurrent injury. An abnormal EEG tracing would consist of slow spike-and-wave discharges (<2.5 Hz). The etiology of LGS is either symptomatic or of unknown origin. In 75% of the cases, it is thought to be symptomatic, suggesting causes such as hypoxic injury or cerebral malformation. In rest of 25% of cases, the cause is unknown. Management of patients with LGS includes AEDs, ketogenic diet, corticosteroids, intravenous immunoglobulins, surgery (corpus callostomy), and vagus nerve stimulation. There are several anesthetic considerations which include presence of other medical conditions associated with epilepsy, interactions of AEDs and anesthetic drugs, avoidance of proconvulsant anesthetic agents whenever possible,[3456] difficulty in assessing mental status due to mental regression or impaired cognition, difficulty in venous cannulation due to contractures, and multiple injuries. All these considerations should be taken care of while giving anesthesia to patients with LGS.

Among inhalational agents, sevoflurane (occasional) and enflurane have epileptogenic activity. Isoflurane, desflurane, and N2O are considered to be safe to use.[5] In our case, we used sevoflurane for induction of anesthesia since it is an agent of choice for pediatric patients. Propofol produces anticonvulsant effect and have been used to treat status epilepticus.[7] Barbiturates have been used to induce burst suppression in patients with status epilepticus.[8] Ketamine even in low dose can induce the alpha and beta activity leading to excitation of the brain.[9] Propofol and barbiturates can be used safely in patients with LGS. Opioids produce less effect on EEG activity. Remifentanil, however, causes electroconvulsive therapy-induced seizure in humans.[10] The common side effects of AEDs, for example, drowsiness, lethargy, and sedation, should also be taken care of. AEDs are also considered to be hepatic enzyme inducers which may alter the anesthetic drug metabolism. The newer AEDs have lower side effects as well as less interaction with anesthetic agents.[1011]

To conclude, it is difficult to determine that particular anesthetic technique would be superior to another for patients with LGS with intractable seizures posted for surgery. Through our reported case and on the basis of available literature, we would advocate propofol and sevoflurane in the anesthetic management of patients with LGS with intractable seizure.

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