Acute encephalopathy in a patient with Dravet syndrome

Fatal Status Epilepticus in Dravet Syndrome

Dravet Syndrome (DS) is burdened by high epilepsy-related premature mortality due to status epilepticus (SE). We surveyed centres within Europe through the Dravet Italia Onlus and EpiCARE network (European Reference Network for Rare and Complex Epilepsies). We collated responses on seven DS SCN1A+ patients who died following refractory SE (mean age 6.9 year, range 1.3–23.4 year); six were on valproate, clobazam, and stiripentol. All patients had previous SE. Fatal SE was always triggered by fever: either respiratory infection or one case of hexavalent vaccination. SE lasted between 80 min and 9 h and all patients received IV benzodiazepines. Four patients died during or within hours of SE; in three patients, SE was followed by coma with death occurring after 13–60 days. Our survey supports the hypothesis that unresponsive fever is a core characteristic feature of acute encephalopathy. We highlight the need for management protocols for prolonged seizures and SE in DS.

The clinical outcome and neuroimaging of acute encephalopathy after status epilepticus in Dravet syndrome

AIM

To analyze the clinical outcome and neuroimaging over a long duration follow-up in the currently largest series of acute encephalopathy after status epilepticus in patients with Dravet syndrome.

METHOD

Clinical and neuroimaging data of patients with Dravet syndrome with a history of acute encephalopathy (coma >24h) after status epilepticus from February 2005 to December 2016 at Peking University First Hospital were reviewed retrospectively.

RESULTS

Thirty-five patients (15 males, 20 females) with a history of acute encephalopathy were enrolled from a total of 624 patients with Dravet syndrome (5.6%). The median onset age of acute encephalopathy was 3 years 1 month. The duration of status epilepticus varied between 40 minutes to 12 hours. Thirty-four patients had a high fever when status epilepticus occurred, and only one had a normal temperature. Coma lasted from 2 to 20 days. Twelve patients died and 23 survived with massive neurological regression. The median follow-up time was 2 years 1 month. Neuroimaging of 20 out of 23 survivors during the recovery phase showed diverse degrees of cortical atrophy with or without subcortical lesions.

INTERPRETATION

Acute encephalopathy after status epilepticus is more prone to occur in patients with Dravet syndrome who had a high fever. The mortality rate is high in severe cases. Survivors are left with severe neurological sequelae but often with either no seizure or low seizure frequency.

WHAT THIS PAPER ADDS

Acute encephalopathy is more prone to occur in patients with Dravet syndrome with a high fever. The mortality rate is high for acute encephalopathy after status epilepticus in patients with Dravet syndrome. Survivors have neurological sequelae.

Vaccination and occurrence of seizures in SCN1A mutation-positive patients: a multicenter Italian study

BACKGROUND

The relation between epileptic seizures and vaccinations is sometimes debated. In the present work, the impact of vaccination on seizure onset and clinical outcome of SCN1A mutation-positive patients is addressed.

METHODS

Seventy-two patients diagnosed with Dravet syndrome or generalized epilepsy with febrile seizure plus, carrying SCN1A mutations or not, were included. Details on vaccination type, temporal relationship between vaccination and seizure occurrence, seizure type at onset and during development, cognitive functioning, and vaccination completion was obtained by reviewing clinical records. Patients were divided into two groups based on the temporal window between vaccination and seizure onset (proximate group: <48 hours; distant group: >48 hours).

RESULTS

Vaccination-related seizures occurred in 25% of patients with SCN1A mutation and 18% of patients without the mutation (no significant difference). The proximate group showed an earlier age at seizure onset and a higher frequency of status epilepticus during development than did the distant group. No other significant differences were found. Subsequent vaccinations did not significantly alter the evolution of the disease.

CONCLUSIONS

Results from this relatively small series provide evidence that vaccinations do not significantly affect clinical and cognitive evolution of Dravet syndrome and generalized epilepsy with febrile seizure plus patients even if they carry SCN1A mutations.

Encephalopathy in children with Dravet syndrome is not a pure consequence of epilepsy

Background

Dravet syndrome (DS) is currently considered as an epileptic encephalopathy, a condition in which epilepsy causes deterioration or developmental delay but preliminary data suggested that cognitive course may worsen independently from epilepsy. Our objective was to prospectively analyze the neuropsychological features in a large cohort of DS patients and its relationships with epilepsy and SCN1A mutation.

Methods

81 examinations were performed in 67 patients with typical DS (9m-24y, 15 longitudinally studied) using Brunet-Lezine (developmental/intelligence quotient [DQ/IQ] and DQ sub-scores), Achenbach, Conners, and a semi-quantitative psychomotor score (SQPS). We studied the correlation between DQ/IQ/SQPS and age, epilepsy characteristics, and whether patients presented SCN1A mutation.

Results

DQ/IQ significantly decreased with age (r = −.53, p < .001), from normal before 2y (mean 80, range 64–105) to low after 3y (mean 48, range 30–69), with hyperactivity and attention disorders hampering learning abilities especially up to 6y. However, raw (not age-adjusted) DQ sub-scores increased with age during the first decade, showing that there is no regression. We did not find any significant correlation between DQ/IQ at last evaluation and epilepsy data, i.e. first seizure (age, type, duration, fever), seizures during the course (type, fever sensitivity), status epilepticus (age of onset, number, fever), photosensitivity, and treatment, except for myoclonus and focal seizures which were associated with a lower QD/IQ after 3y. SCN1A mutated patients (n = 58) seemed to exhibit worse psychomotor course than non-mutated ones (n = 9) (severe SQPS in 26% vs 0%), although their epilepsy tended to be less severe (tonic seizures in 12% vs 44% [p = 0.04], first status epilepticus before 6 m in 26% vs 67% [p = .02], mean number of SE 2.5 vs 4.5 [p = .09]). DQ sub-scores were dissociated throughout the whole course: from onset hand-eye coordination was significantly lower than language, posture and sociability (p < .01). Dissociation seemed to be more frequent in mutated than in non-mutated patients (motor SQPS was normal for in 77% vs 44% [p = 0.017] whereas language SQPS was normal for 47% vs 100%).

Conclusions

Although psychomotor/cognitive delay declines with age, there is no regression. In addition, encephalopathy is not a pure consequence of epilepsy but SCN1A mutation seems to play an additional, direct role.

Are SCN1A gene mutations responsible for genetic susceptibility to subacute sclerosing panencephalitis?

Dravet syndrome, characterized predominantly by myoclonus, has a striking clinical resemblance to subacute sclerosing panencephalitis (SSPE). Patients with Dravet syndrome develop significant mental decline with advancing age of affected child like in SSPE. It is well established that SCN1A gene mutations are associated with Dravet syndrome. Even periodic EEG complexes have been described in Dravet syndrome. In addition to Dravet syndrome, several other types of acute and subacute encephalopathic syndromes having clinical and electroencephalographic resemblance to SSPE are associated with SCN1A gene mutations. SSPE is a devastating progressive inflammatory disorder of the central nervous system. It is caused by persistent infection of the brain by an aberrant measles virus. Only a few of a vast number of measles infected pediatric population develop SSPE. There are several reports describing presence of SSPE is close relatives and it has been described previously in sibling and twin pairs. A genetic susceptibility for development of SSPE is likely. In fact, a variety of genetic abnormalities have already been described in patients with SSPE. It can also be argued that because of striking clinical resemblance between Dravet and various epileptic and encephalopathic syndromes associated with SCN1A gene mutations and SSPE, SCN1A gene abnormalities may also be responsible for susceptibility to SSPE in measles infected children.