Pediatric fulminant malignant hyperthermia with severe electroencephalographic abnormality and brain damage: a case report

Abstract

Background: Malignant hyperthermia is an extremely dangerous condition that can occur with exposure to volatile inhalant anesthetics and depolarizing muscle relaxants, and that requires immediate intervention. Neurological complications have rarely been reported, with no reports of electroencephalographic abnormalities or encephalopathy. Here, we report a case of severe electroencephalographic abnormality in the acute phase of malignant hyperthermia that eventually led to diffuse cerebral cortical damage.

Case presentation: A 15-month-old Japanese boy underwent a Rastelli procedure to correct a double-outlet right ventricle and pulmonary atresia. Sevoflurane was used for induction and maintenance of anesthesia during surgery. After withdrawal from the heart-lung machine, his body temperature rose at a rate of 0.1 ℃/minute, and when he left the operating room, his core body temperature had reached 42 ℃. After admission to the intensive care unit, tachycardia, high PaCO₂, and progressive metabolic acidosis were observed. A clinical grading scale score of 63 indicated malignant hyperthermia, and dantrolene was administered. The pupils were dilated, and the electroencephalogram showed persistent generalized continuous multifocal spikes. Midazolam, levetiracetam, and fosphenytoin were administered without improvement, and thiamylal and ketamine were infused continuously. After the electroencephalogram shifted to burst suppression, the epileptic firing gradually decreased, and the background electroencephalogram became lower in amplitude. Magnetic resonance imaging of the head performed after the patient was hemodynamically stable suggested diffuse cerebral cortical damage. Severe mental retardation, hypertonia, and quadriplegia were observed as neurological complications.

Conclusions: In this case, despite the use of high-dose anticonvulsants, the patient showed severe electroencephalogram abnormality, resulting in diffuse cortical damage. Hyperthermia is known to damage the central nervous system by causing increased brain pressure and cerebral edema, which may have triggered the severe neuronal excitation that we observed in this case. The presence of systemic inflammatory response syndrome and the patient's background, including young age and ethnicity, might also have been factors. Malignant hyperthermia can be complicated by encephalopathy, and continuous electroencephalogram monitoring should be considered.

Keywords: Brain disease; Cardiac surgical procedures; Case report; Electroencephalography; Malignant hyperthermia; Pediatrics.

Fig. 1

Electroencephalographic findings. A Onset: generalized continuous multifocal spikes are observed. B Day 2: High-amplitude multifocal spikes and low voltage are repeatedly observed, considered burst suppression. C Day 5: A decrease in multifocal spikes is observed. D Day 12: A focal seizure occurs in the left occipital region. E Day 14: A decrease in the amplitude of the background electroencephalographic activity can be observed

Fig. 2

Clinical course of the patient. Dantrolene was administered, and body temperature was controlled by CRRT. The patient was treated with midazolam, levetiracetam, and fosphenytoin, but without improvement, and after continuous administration of thiamylal and ketamine, the patient was placed on oral phenobarbital. CRRT continuous renal replacement therapy, BT body temperature, CK creatinine kinase

Fig. 3

Magnetic resonance imaging findings: day 19. a Diffusion-weighted images show diffuse hyperintensity in the cerebral cortex. b T2-weighted images show slight hyperintensity throughout the subcortical area. c T1-weighted imaging shows pale hyperintensity in the cortex, mainly in the occipitoparietal lobe, which is considered to be due to a state of cortical laminar necrosis