Case report: Consecutive hyperbaric oxygen therapy for delayed post-hypoxic leukoencephalopathy resulting from CHANTER syndrome caused by opioid intoxication.

Delayed post-hypoxic leukoencephalopathy (DPHL) is a poorly recognized syndrome characterized by neuropsychiatric symptoms following recovery from an acute hypoxic episode. Although most cases are related to carbon monoxide poisoning, some have been linked to excessive opioid use. Opioid intoxication has recently become known for manifesting the characteristic imaging findings involving cerebellar, hippocampal, and basal nuclei transient edema with restricted diffusion (CHANTER) syndrome. Herein, we present a patient with severe disturbances in consciousness who was initially diagnosed with CO poisoning but was later found to have taken excessive tramadol. Magnetic resonance imaging (MRI) in the acute phase revealed abnormal intensities in the bilateral globus pallidus and the cerebellum, indicative of CHANTER syndrome. After intensive care, his level of consciousness was restored. However, around the 3rd week after hospitalization, his consciousness gradually deteriorated and he developed severe neurological symptoms. Another MRI on day 25 revealed a new diffuse white matter abnormality; DPHL was suspected. Cerebrospinal fluid collected on day 28 revealed significantly elevated myelin basic protein levels. Although it was challenging to decide on a treatment plan, hyperbaric oxygen (HBO) therapy trials were initiated on day 58; the patient's condition improved after a series of HBO sessions. MRI revealed gradual shrinkage of the white matter abnormality. A total of 63 consecutive HBO sessions were performed, leading to the successful resolution of the serious neurological symptoms. While the effectiveness of HBO therapy for DPHL remains inconclusive, especially in opioid-related cases, this patient made a remarkable recovery, likely due to the therapeutic effect of improved cerebral blood flow and oxygenation.

Ictal Direct Current Shifts Preceded Much Earlier Than High Frequency Oscillations After Status: Is It the Effect of Status or Antiseizure Medication?

PURPOSE: While spikes and sharp waves are considered as markers of epilepsy in conventional electroencephalography, ictal direct current (DC) shifts and high-frequency oscillations (HFOs) appear to be useful biomarkers for epileptogenicity. We analyzed how ictal DC shifts and HFOs were affected by focal status epilepticus and antiseizure medications (ASMs). METHODS: A 20-year-old female patient who underwent long-term intracranial electrode implantation for epilepsy surgery presented with 72 habitual seizures and a focal status epilepticus episode lasting for 4 h. Ten, 3, and 10 consecutive habitual seizures were analyzed before the status, after the status, and after ASM (valproate) loading, respectively. RESULTS: Before and immediately after the status, ictal DC shifts remained the same in terms of the amplitude, duration, and slope of DC shifts. High-frequency oscillations also remained the same in terms of the duration, frequency, and power except for the power of the lower frequency band. After ASM loading, the duration, amplitude, and slope of the ictal DC shift were significantly attenuated. The duration, frequency, and power of the HFOs were significantly attenuated. Furthermore, the interval between the DC onset and HFO onset was significantly longer and the interval between the HFO onset and ictal DC shift peak was significantly shorter. CONCLUSIONS: The attenuation of ictal DC shifts and HFOs after ASM loading implies that astrocyte and neuronal activity may be both attenuated by ASMs. This finding may help with our understanding of the pathophysiology of epilepsy and can aid with the discovery of new approaches for epilepsy management.