Cardiac Investigations in Sudden Unexpected Death in DEPDC5-Related Epilepsy.

OBJECTIVE: Germline loss-of-function mutations in DEPDC5, and in its binding partners (NPRL2/3) of the mammalian target of rapamycin (mTOR) repressor GATOR1 complex, cause focal epilepsies and increase the risk of sudden unexpected death in epilepsy (SUDEP). Here, we asked whether DEPDC5 haploinsufficiency predisposes to primary cardiac defects that could contribute to SUDEP and therefore impact the clinical management of patients at high risk of SUDEP. METHODS: Clinical cardiac investigations were performed in 16 patients with pathogenic variants in DEPDC5, NPRL2, or NPRL3. Two novel Depdc5 mouse strains, a human HA-tagged Depdc5 strain and a Depdc5 heterozygous knockout with a neuron-specific deletion of the second allele (Depdc5c/- ), were generated to investigate the role of Depdc5 in SUDEP and cardiac activity during seizures. RESULTS: Holter, echocardiographic, and electrocardiographic (ECG) examinations provided no evidence for altered clinical cardiac function in the patient cohort, of whom 3 DEPDC5 patients succumbed to SUDEP and 6 had a family history of SUDEP. There was no cardiac injury at autopsy in a postmortem DEPDC5 SUDEP case. The HA-tagged Depdc5 mouse revealed expression of Depdc5 in the brain, heart, and lungs. Simultaneous electroencephalographic-ECG records on Depdc5c/- mice showed that spontaneous epileptic seizures resulting in a SUDEP-like event are not preceded by cardiac arrhythmia. INTERPRETATION: Mouse and human data show neither structural nor functional cardiac damage that might underlie a primary contribution to SUDEP in the spectrum of DEPDC5-related epilepsies. ANN NEUROL 2022;91:101-116.

Epileptic spasms in tuberous sclerosis complex.

PURPOSE: To characterize epileptic spasms (ES) occurring after the age of two years in patients with tuberous sclerosis complex (TSC), particularly treatment response to vigabatrin (VGB), which is extremely effective for infantile spasms (IS) in TSC. METHODS: The authors retrospectively reviewed 19 patients with TSC and ES. Medical records were assessed for clinical and treatment data, neurocognitive, EEG, MRI data, and genetic analyses. RESULTS: Of 391 patients with TSC, 19 (4.8%) had ES. Of those with detailed clinical data, six had infantile spasms that persisted after 2 years old, six recurred after an initial remission of infantile spasms (range 2-24 years old), and four occurred de novo over the age of two (range 2-20 years old). All concurrently had other seizure types. One had hypsarrhythmia on EEG. All had brain MRI stigmata typical of TSC. Thirteen had a mutation in TSC2, and one in TSC1. Six patients became spasm-free with medication treatment, including four with VGB, one with VGB in combination with the low glycemic index dietary treatment, and one with felbamate. Five became spasm-free after epilepsy surgery. VGB was not effective for seven patients. The majority continued to have refractory epilepsy. CONCLUSIONS: ES are not uncommon in patients with TSC, especially those with TSC2 mutations. ES in TSC occur in the setting of other seizure types and refractory epilepsy. Hypsarrhythmia is rare. VGB can be effective, but the success of VGB for ES in TSC is not equivalent to that of IS in TSC.

Brain and spinal manifestations of Miller-Dieker syndrome.

A 6-month-old infant with LIS1 17p13.3 deletion-positive Miller-Dieker syndrome (MDS) presented with increased seizures in the setting of a Pseudomonal and Enterococcal urinary tract infection and a buttock abscess associated with a lumbosacral dermal sinus tract. MRI of the neuraxis revealed lissencephaly (figure 1), a tethered cord without lipoma or other mass (figure 2A), and an infected lumbosacral dermal sinus tract. Communication with the spinal canal could not be appreciated (figure 2B). The dermal sinus was explored and found not to extend into the spinal canal. This tract was excised and the lateral abscess drained. Tethered cord release is planned upon resolution of infection.

Clobazam therapy of refractory epilepsy in tuberous sclerosis complex.

Clobazam (CLB) was recently approved by the FDA, but has not been evaluated in tuberous sclerosis complex (TSC). We retrospectively reviewed a cohort of patients with TSC and refractory epilepsy who started CLB over a 5-year period. Clinical characteristics and number of tubers on MRI were assessed. Duration of therapy, therapeutic response and adverse events were recorded. CLB was prescribed in 29 adults and children of whom 72% were cognitively impaired, with a median age at seizure onset of 5 months. Mean duration of CLB therapy was 17.3 months with a 12 and 24-month estimated retention rate of 82% and 68%, respectively. Twenty patients (69%) reported a good response (>50% seizure reduction) at the end of the titration, and six patients (21%) remained good responders after 12 months of CLB therapy. Adverse events occurred in 13 patients, predominantly somnolence and behavioral disorders. One quarter of the responders reported improvement in behavior. No predictive factor for a good response could be identified. CLB appears to be a well-tolerated and valuable option for treatment of refractory epilepsy in TSC.

Posterior glucose hypometabolism in Lafora disease: early and late FDG-PET assessment.

Establishing an early diagnosis of Lafora disease (LD) is often challenging. We describe two cases of LD presenting as myoclonus and tonic-clonic seizures, initially suggesting idiopathic generalized epilepsy. The subsequent course of the disease was characterized by drug-resistant myoclonic epilepsy, cognitive decline, and visual symptoms, which oriented the diagnosis toward progressive myoclonic epilepsy and, more specifically, LD. Early in the evolution in the first case, and before histopathologic and genetic confirmation of LD in both cases, [18]Fluorodeoxyglucose positron emission tomography (FDG-PET) revealed posterior hypometabolism, consistent with the well-known posterior impairment in this disease. This suggests that FDG-PET could help to differentiate LD in early stages from other progressive myoclonic epilepsies, but confirmation is required by a longitudinal study of FDG-PET in progressive myoclonic epilepsy.