Adult patients with Dravet syndrome (DS) may experience a decrease in seizures with age, but motor symptoms and gait become progressively worse, according to study findings published in the journal Neurology.

DS is a treatment-resistant, developmental and epileptic encephalopathy with disease onset in the first year of life. Realizing that limited data are available on DS in adults, the researchers sought to evaluate gait and motor manifestations among older individuals with the disease. The study was conducted among patients who were identified at the Adult Epilepsy Genetic Clinic at Toronto Western Hospital in Toronto, Ontario, Canada, between 2010 and 2020.

The current study had 2 arms — a prospective arm and a cross-sectional arm. The prospective arm enrolled 6 patients (mean age, 32 years) who were examined with the use of a modified version of the Unified Parkinson’s Disease Rating Scale (mUPDRS) in 2014 and then again in 2019. mUPDRS scores were given for gait, resting tremors, facial expression, posture, arising from a chair, and body bradykinesia.


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The cross-sectional arm of the study included mUPDRS testing in patients who were not assessed in 2014, along with an instrumental gait analysis (IGA). The cross-sectional tests were performed in the 2019 to 2020 period. The IGA was carried out in 17 patients with DS (mean age, 31 years); the control group comprised 81 healthy individuals (mean age, 62 years).

Study findings revealed that 5 of 6 participants who were evaluated prospectively over 5 years experienced worsening of parkinsonian manifestations, including their gait. Of the 6 patients in this portion of the study, 2 individuals (aged 47 years and 51 years) who were initially ambulatory could no longer walk 5 years later.

In the cross-sectional analysis of mUPDRS, significantly worse scores with respect to gait (P =.0003), body bradykinesia (P =.01), and arising from a chair (P =.04) were positively associated with age. In the IGA cross-sectional arm, all 17 adults with DS exhibited abnormal gait parameters in all of the domains that were assessed. This group of participants had a worse performance than the healthy, older control group.

Study limitations included its small sample size and the fact the more than one-third of the eligible patients were unable to be enrolled — due largely to the COVID-19 pandemic. Additionally, muscle weakness may be a potential confounding limitation in the evaluation of gait.

It remains unclear why this progressive deterioration in gait and motor function occurs in patients with DS as they age. The researchers concluded that “further research should help explain not only why this happens, but also if it is possible to slow down or even avoid this progression.”

Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 

Reference  

Selvarajah A, Gorodetsky C, Marques P, et al. Progressive worsening of gait and motor abnormalities in older adults with Dravet syndrome. Neurology. Published online April 13, 2022. doi:10.1212/WNL.0000000000200341