Infants with early infantile epileptic encephalopathy or Ohtahara syndrome seem initially neurologically normal, but soon develop increasingly frequent seizures with tonic spasms that resemble infantile spasms and are usually resistant to treatment. Severe progressive mental retardation becomes evident with age. Many die early and most survivals are handicapped. Some may evolve into the West syndrome and some later into the Lennox-Gastaut syndrome (see below). The EEG shows a 'burst suppression' pattern with an almost flat tracing for several seconds, alternating with diffuse, high-amplitude, slow wave-and-spike bursts, poorly modified by sleep-wake stages.(8) The aetiology of Ohtahara syndrome includes usually congenital or acquired malformations of cortical development and diffuse prenatal encephalopathies, the cause of which remains unknown, so far. A recent report on a case of Ohtahara syndrome included a metabolic defect with cytchrome oxidase deficiency/9

Early myoclonic epileptic encephalopathy is another epileptic syndrome occurring during infancy with a grim prognosis. (!9 The predominant seizure pattern is erratic, paroxysmal, fragmentary myoclonus, often associated with other seizure types. Brain malformations are not so common as in Ohtahara syndrome. Metabolic disorder has been suspected.

Infantile spasms occur usually at the ages of 4 to 6 months and in 90 per cent of cases during the first year of life. The events resemble the Moro reflex with sudden, brief flexion of neck and trunk, raising both arms forwards or sideways, sometimes with flexion at the elbows, and flexion of legs at the hips. Less often, the legs extend at the hips. At the early stage flexion of neck may be the only or main feature; this may be followed by more complex and dramatic attacks later on. A cry is often associated with the attack either as part of the attack or occurring afterwards as an expression of disquiet. The spasms are usually symmetric, but may be asymmetric or even unilateral. The EEG is chaotic with slow waves of high voltage intermixed with diffuse or asynchronous spikes in both hemispheres or in the contralateral hemisphere in unilateral cases. This pattern is called hypsarrhythmia. Infants with unilateral spasms need to be examined using a positron emission tomography scan, as contralateral hypometabolism may be due to cortical dysplasia, a condition which may be treatable by resective epilepsy surgery. Aetiology is usually symptomatic including brain abnormalities due to intrauterine infections such as toxoplasmosis, cytomegalic inclusion disease, or rubella. Other aetiologies are brain malformations due to unknown cause. Infants with Down syndrome or tuberous sclerosis may develop infantile spasms. West syndrome comprises the triad of infantile spasms, hypsarrhythmia, and mental retardation.

Progressive degenerative brain diseases and neoplasms are rare causes of infantile spasms. Also neurometabolic disorders such as phenylketonuria, maple syrup urine diseases, non-ketotic or ketotic hyperglycinaemia, and urea cycle defects may lead to infantile spasms.

Severe myoclonic epilepsy in infants includes generalized or unilateral febrile clonic seizures, secondary appearance of myoclonic jerks, and often partial seizures. All the children affected suffer from mental retardation from the second year of life onwards. Ataxia, signs of upper motor neurone involvement, and interictal myoclonus may appear.^1

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