Familial Unverricht-Lundborg disease: a clinical, neurophysiologic, and genetic study

Clinical and molecular characterization of Unverricht-Lundborg disease among Egyptian patients

BACKGROUND AND PURPOSE

Unverricht-Lundborg disease (ULD) is a common type of progressive myoclonic epilepsy (PME). It is caused mostly by biallelic dodecamer repeat expansions in the promoter region of CSTB gene. Despite highly prevalent in the Mediterranean countries, no studies have been reported from Egypt. This article study the presence of CSTB gene mutations among Egyptian patients clinically suspected with ULD, and describes the clinical and genetic characteristics of those with confirmed gene mutation.

METHODS

Medical records of patients following up in two specialized epilepsy clinics in Cairo, Egypt were retrospectively reviewed. Twenty patients who belonged to 13 unrelated families were provisionally diagnosed with ULD based on the clinical presentation. Genetic testing was done. Clinical characteristics, demographic data and EEG findings were documented.

RESULTS

Genetic studies confirmed the presence of the CSTB dodecamer repeat expansion in 14 patients from 8 families (frequency 70 %). The mean duration of the follow-up was 5 years. Male to female distribution was 1:1 with a mean age of onset 9.7 years. Consanguinity was noted in 4 families. Eight patients had their first seizure between the age of 10 and 20 years. Myoclonic jerks ranged in severity from mild in three unrelated patients to severe in one. Only 3 had cognitive impairment.

CONCLUSION

Our study confirms the presence of CSTB mutation among Egyptian patients suspected with ULD. There was no clear phenotype-genotype correlation among the studied group of patients. In addition, we noticed variable inter and intra familial severity among patients from the same family.

Progressive volume loss and white matter degeneration in cstb-deficient mice: a diffusion tensor and longitudinal volumetry MRI study

Unverricht-Lundborg type progressive myoclonus epilepsy (EPM1, OMIM 254800) is an autosomal recessive disorder characterized by onset at the age of 6 to 16 years, incapacitating stimulus-sensitive myoclonus and tonic-clonic epileptic seizures. It is caused by mutations in the gene encoding cystatin B. Previously, widespread white matter changes and atrophy has been detected both in adult EPM1 patients and in 6-month-old cystatin B-deficient mice, a mouse model for the EPM1 disease. In order to elucidate the spatiotemporal dynamics of the brain atrophy and white matter changes in EPM1, we conducted longitudinal in vivo magnetic resonance imaging and ex vivo diffusion tensor imaging accompanied with tract-based spatial statistics analysis to compare volumetric changes and fractional anisotropy in the brains of 1 to 6 months of age cystatin B-deficient and control mice. The results reveal progressive but non-uniform volume loss of the cystatin B-deficient mouse brains, indicating that different neuronal populations possess distinct sensitivity to the damage caused by cystatin B deficiency. The diffusion tensor imaging data reveal early and progressive white matter alterations in cystatin B-deficient mice affecting all major tracts. The results also indicate that the white matter damage in the cystatin B-deficient brain is most likely secondary to glial activation and neurodegenerative events rather than a primary result of CSTB deficiency. The data also show that diffusion tensor imaging combined with TBSS analysis provides a feasible approach not only to follow white matter damage in neurodegenerative mouse models but also to detect fractional anisotropy changes related to normal white matter maturation and reorganisation.

Sensorimotor, visual, and auditory cortical atrophy in Unverricht-Lundborg disease mapped with cortical thickness analysis

BACKGROUND AND PURPOSE

EPM1, caused by mutations in the CSTB gene, is the most common form of PME. The most incapacitating symptom of EPM1 is action-activated and stimulus-sensitive myoclonus. The clinical severity of the disease varies considerably among patients, but so far, no correlations have been observed between quantitative structural changes in the brain and clinical parameters such as duration of the disease, age at onset, or myoclonus severity. The aim of this study was to evaluate possible changes in CTH of patients with EPM1 compared with healthy controls and to correlate those changes with clinical parameters.

MATERIALS AND METHODS

Fifty-three genetically verified patients with EPM1 and 70 healthy volunteers matched for age and sex underwent 1.5T MR imaging. T1-weighted 3D images were analyzed with CTH analysis to detect alterations. The patients were clinically evaluated for myoclonus severity by using the UMRS. Higher UMRS scores indicate more severe myoclonus.

RESULTS

CTH analysis revealed significant thinning of the sensorimotor and visual and auditory cortices of patients with EPM1 compared with healthy controls. CTH was reduced with increasing age in both groups, but in patients, the changes were confined specifically to the aforementioned areas, while in controls, the changes were more diffuse. Duration of the disease and the severity of myoclonus correlated negatively with CTH.

CONCLUSIONS

Cortical thinning in the sensorimotor areas in EPM1 correlated significantly with the degree of the severity of the myoclonus and is most likely related to the widespread stimulus sensitivity in EPM1.

Clinical picture of EPM1-Unverricht-Lundborg disease

Unverricht-Lundborg disease (ULD), progressive myoclonic epilepsy type 1 (EPM1, OMIM254800), is an autosomal recessively inherited neurodegenerative disorder characterized by age of onset from 6 to 16 years, stimulus-sensitive myoclonus, and tonic-clonic epileptic seizures. Some years after the onset ataxia, incoordination, intentional tremor, and dysarthria develop. Individuals with EPM1 are mentally alert but show emotional lability, depression, and mild decline in intellectual performance over time. The diagnosis of EPM1 can be confirmed by identifying disease-causing mutations in a cysteine protease inhibitor cystatin B (CSTB) gene. Symptomatic pharmacologic and rehabilitative management, including psychosocial support, are the mainstay of EPM1 patients' care. Valproic acid, the first drug of choice, diminishes myoclonus and the frequency of generalized seizures. Clonazepam and high-dose piracetam are used to treat myoclonus, whereas levetiracetam seems to be effective for both myoclonus and generalized seizures. There are a number of agents that aggravate clinical course of EPM1 such as phenytoin aggravating the associated neurologic symptoms or even accelerating cerebellar degeneration. Sodium channel blockers (carbamazepine, oxcarbazepine) and GABAergic drugs (tiagabine, vigabatrin) as well as gabapentin and pregabalin may aggravate myoclonus and myoclonic seizures. EPM1 patients need lifelong clinical follow-up, including evaluation of the drug-treatment and comprehensive rehabilitation.

Chromosome 21 abnormalities: a review and report of a case of Erondu-Cymet syndrome

The co-existence of rare clinical findings in a patient with a genetic abnormality has often led to the characterization of new syndromes. Although these genetic syndromes are generally rare, the pathophysiology of these disorders has broadened our understanding of common medical conditions. The variety of disorders that map to chromosome 21 provide insight into the effects of lifelong low pO2 and poor perfusion on various organs. In discovering the different disorders that map specifically to chromosome 21, we can characterized, treat and even prevent some medical conditions. We present the case of a man whose incidental finding of hypoxemia lead to the discovery of many unusual disorders that appear to be related to abnormalities in chromosome 21.

Progressive myoclonic epilepsy: A clinical, electrophysiological and pathological study from South India

Progressive myoclonic epilepsy (PME) is a syndrome complex encompassing different diagnostic entities and often cause problems in diagnosis. We describe the clinical, electrophysiological and pathological features of 97 patients with the diagnosis of PME evaluated over 25 years. Case records of confirmed patients of Neuronal ceroid lipofuscinosis (NCL = 40), Lafora body disease (LBD = 38), Myoclonic epilepsy with ragged red fibers (MERRF = 10), and probable Unverricht-Lundberg disease (ULD = 9) were reviewed. The mean age at onset in patients with NCL (n = 40) was 5.9+/-9.1 years (M:F:: 28:12). Subtypes of NCL were: late infantile (n = 19), infantile (n = 8), juvenile (n = 11) and adult (n = 2) NCL. EEG (n = 37) showed varying degree of diffuse slowing of background activity in 94.6% and epileptiform discharges in 81.1% of patients. Slow frequency photic stimulation evoked photo-convulsive response in 5 patients only. Giant SSEP was demonstrated in 7 and VEP study revealed a prolonged P100 (2) and absent waveform (7). Electrophysiological features of neuropathy were present in 3 patients. Presence of PAS and Luxol Fast Blue (LFB) positive, auto fluorescent (AF) ceroid material in brain tissue (n = 12) and electron microscopy of brain (n = 5), skin (n = 28) and muscle (n = 1) samples showing curvilinear and lamellar bodies established the diagnosis. Patients of LBD (mean age of onset at 14.4+/-3.9 years, M:F:: 24:14) with triad of PME symptoms were evaluated. EEG (n = 37) showed variable slowing of background activity in 94.6% and epileptiform discharges in 97.4%. Photosensitivity with fast frequency was observed only in 5 patients. CT (n = 32) and MRI (n = 4) revealed diffuse cortical atrophy. Giant SSEP was demonstrated in 24 patients of LBD while VEP study revealed a prolonged P100 (4) and absent waveform (8). Electrophysiological features of neuropathy were present in one patient. Diagnosis was established by the presence of PAS positive diastase resistant, Lugol's Iodine labeled inclusions in sweat glands of axillary skin (n = 35), brain (n = 2) and liver (n = 1). Ten patients with MERRF (mean age at onset: 14.6+/-5.8 years; M: F:: 3:2) had triad of PME symptoms. Muscle biopsy revealed oxidative reaction product and classical ragged red fibers. In nine patients of PME without cognitive decline, probable diagnosis of ULD (mean age at onset: 13.8+/-9.5 years) was considered after biopsy of skin and/or muscle excluded other forms of PMEs. Neuronal ceroid lipofuscinosis and Lafora body diseases were the common causes of PME in the series from south India. This is one of the largest series from the Indian subcontinent to the best of our knowledge. Photosensitivity is notably less common in LBD/NCL in this series distinctly different from those reported in the literature. Further exploration is required to determine whether different genotype is responsible. Morphological changes were helpful in diagnosis and could be confirmed by biopsy of peripheral tissues like skin and muscle in majority (60%). Electron microscopy was helpful in the diagnosis NCL and MERRF.

Electroencephalogram in developmental delay: specific electroclinical syndromes

The electroencephalogram (EEG) plays an important role in the evaluation of a child with developmental delay. An EEG is often required to classify seizures in children with developmental delay. Equally important is the role of the EEG in the identification of specific electroclinical syndromes in children who may or may not manifest seizures. Specific electroclinical syndromes include the acquired epileptiform aphasia syndrome, Landau-Kleffner syndrome, and electrical status epilepticus during slow wave sleep. Other clinical situations where the EEG offers diagnostic and prognostic information, such as subacute sclerosing encephalitis, progressive myoclonus epilepsies, Rett syndrome, and Lennox Gastaut syndrome are also discussed.