Sulthiame impairs mitochondrial function in vitro and may trigger onset of visual loss in Leber hereditary optic neuropathy

Sulthiame use in children with pharmacoresistant epilepsies: A retrospective study

OBJECTIVE

This retrospective study aimed to assess the efficacy and tolerability of sulthiame as an add-on treatment in children with pharmacoresistant epilepsies.

METHODS

All patients with epilepsy who received sulthiame at Montreal Children's Hospital over an 11-year period were included. Medical charts were reviewed, and extracted data included patient age and sex, seizure types, epilepsy syndrome, electroencephalography (EEG) reports, brain imaging reports, antiseizure treatments trialed, starting and final dose of sulthiame, duration of sulthiame treatment, adverse events attributed to sulthiame, and seizure frequency before and after sulthiame treatment. EEG studies were also analyzed and spike-wave index (SWI) in the first 10 min of sleep was calculated.

RESULTS

Sixteen patients were included, all of whom had pharmacoresistant epilepsies (mean of 9.9 trials of other antiseizure treatments). Six had genetic diagnoses, four had in utero/perinatal acquired brain injury, one had a suspected focal cortical dysplasia, and five were idiopathic. Ten patients had developmental and epileptic encephalopathy with spike-wave activation in sleep, three had Lennox-Gastaut syndrome, and one each had sleep-related hyperkinetic epilepsy, self-limited epilepsy with centrotemporal spikes, and mixed generalized and multifocal epilepsy. Of the 12 patients with uncontrolled seizures at the time of sulthiame initiation, 4 had improvement in seizure frequency, including 2 who became seizure free. Eight patients had EEG data available that allowed calculation of sleep SWI; from this group, SWI decreased from 81.1% +/- 17.6% to 45.1% +/- 36.5% (p = .007). The most common adverse events reported were somnolence/drowsiness, aggression, and increased seizure frequency. Of the patients with genetic etiologies, significant positive responses were seen in patients with pathogenic variants in NDUFS1 and SATB1.

SIGNIFICANCE

These data demonstrate the therapeutic potential of sulthiame, even in patients with highly pharmacoresistant epilepsy. Improvements may be seen in both seizure frequency and sleep SWI.

Vitamin B12 in Leber hereditary optic neuropathy mutation carriers: a prospective cohort study

Background

Leber hereditary optic neuropathy (LHON) is the most common mitochondrial disorder, frequently resulting in acute or subacute severe bilateral central vision loss. Vitamin B12 deficiency is also a known cause of optic neuropathy through mitochondrial dysfunction. Here we evaluated the prevalence and clinical significance of vitamin B12 deficiency in a large cohort of LHON patients and asymptomatic mutation carriers from a tertiary referral center.

Methods

From the Munich LHON prospective cohort study, participants included all LHON patients and asymptomatic LHON mutation carriers, who were recruited between February 2014 and March 2020 and consented to participate. Neurological, general, and ophthalmological examinations were regularly performed, as were laboratory tests. Vitamin B12 deficiency was diagnosed if serum vitamin B12 was below 201 pg/mL, or if 201–339 pg/mL plus low serum holotranscobalamin or elevated serum methylmalonic acid or elevated total plasma homocysteine.

Results

We analyzed 244 subjects, including 147 symptomatic LHON patients (74% males) and 97 asymptomatic mutation carriers (31% males). Median age at study baseline was 34 years (range 5–82 years). The prevalence of vitamin B12 deficiency was higher for LHON mutation carriers than for the general population in all age categories. This was statistically significant for the LHON mutation carriers under 65 years (21% vs. 5–7%, p = 0.002). While vitamin B12 deficiency prevalence was not statistically different between LHON patients and asymptomatic mutation carriers, its clinical correlates, e.g., macrocytosis and polyneuropathy, were more frequent in the subgroup of LHON patients. Excessive alcohol consumption was a significant predictor of vitamin B12 deficiency (p < 0.05).

Conclusions

The high prevalence of vitamin B12 deficiency in LHON mutation carriers, both asymptomatic mutation carriers and LHON patients, highlights the need for regular vitamin B12 screening in this population, in order to ensure early treatment, aiming for better outcomes. Our study is not conclusive regarding vitamin B12 deficiency as determinant for disease conversion in LHON, and further research is warranted to disentangle the role of vitamin B12 in the pathophysiology and prognosis of LHON.