Dravet syndrome and parkinsonism

Effect of levodopa on pathological gait in Dravet syndrome: A randomized crossover trial using three-dimensional gait analysis

OBJECTIVE

Individuals with Dravet syndrome (DS) exhibit progressive gait disturbance. No quantitative studies have been conducted to evaluate the effectiveness of medication for gait disturbance. Therefore, the aim of this study was to evaluate the effectiveness of levodopa for pathological gait in people with DS using three-dimensional gait analysis (3DGA).

METHODS

Nine individuals with DS, ages 6-20 years, participated in a crossover study of levodopa and were randomly assigned to the levodopa precedence or no levodopa precedence group. Levodopa/carbidopa hydrate was prescribed at a dose of 5 mg/kg/day (body weight <60 kg) or 300 mg/day (body weight ≥60 kg). The medication was taken for 4-6 weeks (4-week washout period). 3DGA was performed three times before the study, with and without levodopa. A mixed-effects model was used to evaluate the effectiveness of levodopa. The primary outcome was the change in the Gait Deviation Index (GDI). In addition, spatiotemporal gait parameters, 6-minute walking distance (6MD), and balance were evaluated. The correlation between the effectiveness of levodopa and age or gait performance before starting levodopa was analyzed.

RESULTS

Levodopa improved the GDI by 4.2 points, (p = .029), 6MD by 52 m (p = .002), and balance test result by 4.1 mm (p = .011) in participants with DS. No severe adverse events were observed, with the exception of one participant, who exhibited fever and consequently stopped taking levodopa. Levodopa was more effective in younger participants with a higher baseline gait performance.

SIGNIFICANCE

Our randomized crossover trial showed that levodopa has the potential to improve gait disturbance in people with DS.

Motor and behavioral phenotype of Dravet syndrome in adulthood

In a comparative cross-sectional study, 26 adult individuals with clinically typical, genetically confirmed Dravet syndrome (DS) and an equal number of individuals with early onset, problematic epilepsy, and intellectual disability (ID) of comparable severity were included. The aim of the study was to find out whether patients with DS could be clearly distinguished from the comparison group with regard to neurological and behavioral symptoms. Significant differences were found in that individuals with DS clearly more frequently exhibited a symptom cluster characterized by bradykinesia, hypomimia, hypophonia, (spastic) increased muscle tone, ataxia, sthenic perseveration, and a special interest in colors. To these symptoms must be added, according to the findings of previous examinations, mastication, camptocormia/antecollis on the one hand, and the tendency to visual hallucinations on the other hand, in order to define one neuropsychiatric phenotype of DS in adulthood. To these symptoms must be added, according to the findings of previous investigations, crouch gait with camptocormia/antecollis on the one hand, and the tendency to visual hallucinations on the other hand, in order to define one outlined neuropsychiatric phenotype of DS in adulthood.

Gamma-decanolactone: Preliminary evaluation as potential antiparkinsonian drug

Treatment of Parkinson's disease (PD) includes the use of monoamine oxidase-B (MAO-B) inhibitor drugs. In this work we have evaluated the possible gamma-decanolactone (GD) effect in vitro to inhibit the A and B isoforms of human monoamine oxidase (hMAO) enzyme and their citotoxicity in human hepatoma cell line (HepG2). Also, binding studies to A₁, A_2A A_2B and A₃ adenosine receptors were performed. A docking study of gamma-decanolactone has been carried out with the molecular targets of MAO-A and MAO-B isoforms. The physicochemical properties and ability to cross physiological barriers, as the blood brain barrier (BBB), was elucidated by computational studies. The in vivo assays, the rota-rod test, body temperature assessment and open field test were performed in reserpinized mice (1.5 mg/kg, i.p.; 18:00 before) to evaluate the effect of gamma-decanolactone (300 mg/kg), alone or associated with Levodopa plus Benserazide (LD + BZ, 100:25 mg/kg, i.p.). Gamma-decanolactone inhibited preferentially the MAO-B in a reversible manner, with an inhibitory concentration of 50% (IC₅₀) 55.95 ± 9.06 μM. It was shown to be a safe drug since only at the highest concentration decreased the viability of HepG2 cells. It also does not bind to adenosine receptors investigated in this study. The molecular docking study show that the gamma-decanolactone ligand adopts a relatively compact conformation in the active site of hMAO-B, while we note an extended conformation of gamma-decanolactone ligand in the hMAO-A isoform. The physicochemical properties obtained, and the theoretical models utilized for the evaluation of ability to cross the BBB, predict a good gamma-decanolactone bioavailability and access to the central nervous system (CNS). In the in vivo studies, gamma-decanolactone partially reversed the ataxia of the reserpinized mice at 01:00 h and 01:30 h post-administration. Concomitant treatment of gamma-decanolactone with LD + BZ, at 01:30 h showed a potentiation of the reversibility of ataxia and facilitated the reversal of hypothermia caused by reserpine for all measured times (P <0.01 vs vehicle), except at 24:00 h, but not reversed the hypokinesia in the open field test. In summary, the results herein obtained and in conjunction with previous studies, suggest that gamma-decanolactone could be a drug with potential utility as antiparkinsonian drug.

Dravet syndrome with parkinsonian symptoms and intact dopaminergic neurons: A case report

INTRODUCTION

Dravet syndrome (DS) is severe myoclonic epilepsy in infancy and associated with a heterozygous mutation of the gene for the sodium channel alpha 1 subunit (SCN1A). Recently, adult patients with DS have been reported to show parkinsonism, but no corresponding neuroimaging data are available. Here, we present neuroimaging data in 2 adult patients with DS showing parkinsonian symptoms.

CASE REPORT

Case 1: A man who had intractable seizures from the age of 1 year and 2 months was diagnosed with DS at 7 with a mutation in the SCN1A gene. At 18, he had parkinsonian symptoms such as masked face and bradykinesia. At 20, he was admitted to our department. Dopamine transporter single-photon emission computed tomography (DAT SPECT) showed no decrease in striatal binding of ¹²³I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane (¹²³I-FP-CIT), and myocardial scintigraphy showed no decrease in cardiac uptake of ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG). Levodopa showed no significant improvement in his symptoms. Case 2: A woman who had febrile seizures at 4 months of age and myoclonic seizures at 1 year and 5 months was diagnosed with DS at 31. She had myoclonus, resting tremor, hypertonia, antecollis, crouch gait, and bradykinesia. DAT SPECT imaging showed no decrease in striatal FP-CIT binding, and levodopa did not improve her symptoms.

DISCUSSION

The normal DAT SPECT and ¹²³I-MIBG results suggest that dopaminergic neurons projecting onto striatal neurons were not impaired in our patients, explaining the lack of response to levodopa. Thus, dopamine imaging can help to guide treatment decisions in patients with DS and parkinsonism.