Brain atrophy documented in prolonged status epilepticus
medwireNews: Using magnetic resonance imaging (MRI), US investigators have found evidence of brain atrophy in patients with super-refractory status epilepticus (SRSE) despite seizure control treatment with anaesthetic agents.
“The reason for the progressive brain atrophy is not known but may be owing to reversible cerebral edema, ongoing subclinical seizures that are not detected by scalp [electroencephalography], direct effects of anesthetic medication therapy, or disuse of therapy”, writes the team from Mayo Clinic in Rochester, Minnesota.
This chart review included 19 individuals (median age 41 years) with SRSE – defined as SE that continues or recurs a day or more after initiation of anaesthetic therapy – who had an MRI scan within 2 weeks of SRSE onset and another one within 6 months of SRSE resolution, with at least a week between scans.
The ventricular brain ratio (VBR) was measured at disease onset and during follow-up from T2-weighted fluid-attenuated inversion recovery images, by dividing the area of the lateral ventricles in a single slice by the total brain area. And the change in VBR, expressed as a percentage of the baseline value, was calculated, such that a higher value indicated greater parenchymal loss.
As reported in JAMA Neurology, the median VBR values at the initial and later scans were 0.06 and 0.08, respectively, and equated to a change in VBR of 23.3%.
Editorialist Andrew Cole (Massachusetts General Hospital, Boston, USA) points out that although the value is “striking”, it does not suggest a reduction in brain volume of nearly a quarter, “because VBR may change as the result of an increase in ventricular area, a decrease in whole brain area, or a combination of both”.
He continues: “It would have been instructive for the authors to provide a table listing the actual measured ventricular and whole brain areas, along with some measurement of interobserver variability, to allow the reader to better consider the significance of the [change in VBR] observed.”
Cole also notes that increases in ventricular area could be transient, “perhaps due to altered cerebrospinal fluid pressure dynamics” – a point that could potentially have been addressed by the use of serial scans.
The research team also found that change in VBR correlated significantly and positively with duration of anaesthetic use and hospital stay, but negatively with age. By contrast, there was no significant correlation between change in VBR and functional outcome, as assessed by the modified Rankin scale, a finding that the study authors and the editorialist find surprising.
But given this result, Sara Hocker and co-researchers suggest that “atrophy per se may not determine poor recovery and, therefore, should not be used as the sole argument to withdraw life-sustaining measures”.
And they conclude: “Future studies should focus on which areas are most affected, assess the association of atrophy with relevant clinical variables, and importantly, examine the influence of atrophy development on long-term cognitive function in survivors of SRSE.”
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