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Lactic acidosis is present in blood and urine in Leigh's syndrome. This is usually due to X-linked or autosomal recessive nuclear gene mutations of one of the mitochon-drial respiratory chain complex I or IV enzymes or pyruvate dehydrogenase (X-linked PDHA1 gene). About 30 are due to mutations in mitochondrial DNA, which have been identified in at least 11 mitochondrial genes. The diagnostic features are a subacute encephalopathy, seizures (myoclonic or tonic-clonic), and progressive dementia with cerebellar and brainstem signs. Motor abnormalities include hypotonia, spasticity, ataxia, involuntary movements and bulbar problems. Vomiting, hyperventilation and abnormalities of thermoregulation are common. Optic atrophy, pigmentary retinopathy, deafness and cardiomyopathy are sometimes present. On imaging, basal ganglia lucencies are highly characteristic, and proton magnetic resonance spectro
At least 17 autosomal recessive disorders are described due to abnormalities of 11 genes coding for peroxisomal enzymes. These enzymes act as metabolic pathways in the oxidation of long-chain fatty acids, necessary for myelin production. Zellweger syndrome and neonatal adrenoleuco-dystrophy are examples, presenting as severe seizure disorders often starting in the neonatal period and including all seizure types including infantile spasm. Other features include poor feeding, severe intellectual regression, bony stippling (chondrodysplasia punctata), retinal dystrophy, hearing loss, hypotonia and dysmorphic features (including high palate, high forehead and shallow orbital ridges). The EEG is severely abnormal. In some cases polymicrogyria is present. The diagnosis is made by measuring serum long-chain fatty acids in plasma, and then fibroblast culture. Mutations in 11 different PEX genes those that encode peroxins have been identified. Mutations of the PEX1 is the most common cause,...
Several other less common epilepsies result from simple Mendelian inheritance, such as the progressive myoclonus epilepsies. However, these disorders are exceedingly rare and generally require diagnostic technologies not available in developing world settings. Mitochondrial disorders include myoclonic epilepsy with ragged red fibers (MERRF) and mitochondrial encephalomy-opathy with lactic acidosis and stroke-like episodes (MELAS). The overlapping features of mitochondrial disorders include seizures, dementia, progressive external ophthalmo-plegia, sensory neural hearing loss, cardiac abnormalities, and elevated levels of lactate and pyruvate.
Based on the clinical presentation and progression of cognitive loss, associated symptoms, and ethnic origin, most of the other progressive myoclonic epilepsies can be potentially diagnosed. Other than the canonical features of myoclonus, generalized seizures, ataxia, and ragged red fibers in muscle, there are frequent other clinical abnormalities noted in MERRF, including sensorineural hearing loss, peripheral neuropathy, short stature, exercise intolerance, and optic atrophy. Less frequent clinical signs reported are cardiomyopathy, preexcitation arrhythmia (Wolf-Parkinson-White), pigmentary retinopathy, ophthalmoparesis, pyramidal signs, and multiple lipomas
The syndrome of acquired aphasia with convulsive disorder in children was first described by Landau and Kleffner32 in six children with normal early language development who suddenly developed aphasia in relation to an epileptic disorder. The language disturbance typically first involves verbal comprehension (classicly a verbal auditory agnosia) that may be mistaken for an acquired deafness. The usually gradual deterioration in verbal production follows the loss of comprehension, occurs together with it, or even precedes it. Several variables can influence the severity and the duration of the language disorder frequency of the epileptic discharges in the language zones, the duration of the epileptic disorder, the spread of the epileptic discharges to the homologous contralateral cortex, and the efficacy of the AED therapy.9394
Myoclonus epilepsy with ragged red fibers was first described in cases with a florid clinical myopathy and myoclonus epilepsy (22, 23). It is now clear that the clinical spectrum of MERRF is extremely broad. It should be suspected in a wide variety of situations, even when clinical and pathologic evidence of myopathy are absent (24). Symptoms may begin at any age, and there may be marked intrafamily variation in the age of onset and clinical severity (24, 25). The clinical features include myoclonus, tonic-clonic seizures, dementia, and ataxia, with less common findings of myopathy, neuropathy, deafness, and optic atrophy. Some cases show striking axial lipomas. Occasional patients or families have focal neurologic events, and there is an overlap with the syndrome of mitochondrial encephalomyopathy, lactic acido-sis, and strokelike episodes (MELAS), in which strokelike Diagnosis can usually be suspected clinically but may be difficult to confirm with laboratory markers. The clinical...
Although patients with the PME syndrome superficially may appear to have similar clinical features, knowledge of the specific clinical patterns of the common causes of PME often allows the differential diagnosis to be narrowed. Age at onset of symptoms provides some guidance in making the diagnosis, although MERRF may begin at any age. Certain seizure patterns are helpful very prominent myoclonus suggests Unverricht-Lundborg disease, MERRF, or sialidosis. Partial seizures, particularly of occipital origin, can occur in a variety of the disorders but are often noted in Lafora disease. Characteristic fun-dal changes are almost invariable in sialidosis and are frequent in the NCLs. Dementia is a constant feature of Lafora disease and NCLs, whereas it is characteristically absent or mild in Unverricht-Lundborg disease and sialidosis type I. The presence of deafness, lipomas, optic atrophy, myopathy, or neuropathy are clinical pointers to MERRF. Neuropathy may also occur in sialidosis....
The onset of LKS usually occurs in children older than 4 years (26), with a range of 3 to 10 years (27). LKS may first manifest as an apparent word deafness or a verbal auditory agnosia. Seizures and behavior disturbances, particularly attention deficits and hyperactivity, each occur in approximately two-thirds of children with LKS (5). The majority of cases are classified as idiopathic, although any pathologic process affecting the auditory cortex may cause LKS. Symptomatic cases have been described (see the section on differential diagnosis), and we have seen symptomatic LKS caused by a left temporal oligodendroglioma, with clinical improvement noted after resection. The classical features of LKS are a verbal auditory agnosia (word deafness) followed by language regression, seizures, or both in a previously normal child who has an epileptiform EEG. An important corollary is normal hearing, because a central disorder cannot be diagnosed in the presence of peripheral dysfunction....
Malformations in the fetus. A birth defect may affect how the body looks, function, or both. It may be found before birth, at birth, or anytime after birth. Most defects are discovered within the first year of life. Some birth defects (cleft lip or clubfoot) are easy to see, but others (heart defects or hearing loss) are found using special tests (X-rays, CAT scans, echocardiography, or hearing tests). Birth defects can vary from mild to severe some may cause the baby to die. Babies with birth defects may need surgery or other medical treatments, but with medical care they usually lead normal lives.
The mitochondrial cytopathy that typically causes progressive myoclonic epilepsy is the syndrome of myoclonus epilepsy with ragged red fibres (MERRF). This is a multisystem disorder with a very variable phenotype, in which myoclonic seizures are often the first symptom, followed by generalized epilepsy, myopathy, ataxia and dementia. Other features are short stature, deafness, optic atrophy, retinopathy, ophthalmoparesis and cardiomyopathy with
Difficulty in the diagnosis of the syndrome of Jervell and Lange-Nielsen, in which congenital deafness is associated with an autosomal recessive inheritance.23 Much more difficult is the Romano-Ward syndrome, which is dominantly inherited but with incomplete penetrance. There is a degree of overlap between the stimuli which induce the neurally mediated syncopes and those which trigger the ventricular tachyarrhythmias of the long QT syndrome. The two situations in which cardiac arrhythmias have to be actively considered are those in which convulsions occur
Prenatal cytomegalovirus (CMV) infection occurs through the first to third trimesters in symptomatic patients. CMV has an affinity for the rapidly proliferating subependymal cells lining the ventricles. Viral multiplication and subsequent calcium deposition result in brain disruption or dysgenesis with periventricular or diffuse calcification. Microcephaly (50 ), hydrocephalus, neuronal migration disorders, porencephaly, and polycystic encephalomalasia are observed. Mental retardation, visual disturbance, hearing loss, language disorders, and epilepsy can be observed.23,29,30
Juvenile sialidosis type II presents as a PME with features similar to those of sialidosis type I except that onset is sometimes a little later. There may be additional features of coarse facies, corneal clouding, dysostosis multiplex, hearing loss, and low intellect, which may be present from early life (59, 60).
Skin rashes and striking neurologic symptoms with seizures are prominent signs of biotinidase deficiency. Hypotonia, developmental delay, and seizures are presenting features in the neonatal form. In the late-onset type, 1 week to 2 years onset, the most common presenting feature is seizures. The most common seizure type is myoclonus, although generalized tonic-clonic and focal clonic seizures have been described (61). Ataxia and hypotonia are present, as are rash and alopecia. Hearing loss may occur. Treatment is oral biotin with rapid response within 24 hours (61, 62).
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