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WE have investigated the age-dependent profile of two groups of NMDAR1 mRNA isoforms, the NR10XXand the NR11XX, which are characterized by the absence and the presence, respectively, of an N-terminal positioned 21 amino acid insert. mRNAs of the two spliced variants were investigated at different ages in discrete rat brain areas by means of the reverse transcription-polymerase chain reaction. The existence of regional variations was confirmed as well as a region-specific pattern of NR10XX/1XXratio and its age-dependent changes. At 6 months, the ratio was > 3 in prosencephalic structures and < 1 in metencephalic regions. The greatest age-related changes were found in the cerebellum that switched from a maximal ratio of 5.1 ± 0.4 at day 6 through a progressive decay down to the value of 0.3 ± 0.04 at 24 months. Age-dependent changes of the different NR1 spliced variant mRNAs are relevant to understand possible regulatory mechanisms of the pharmacological properties and functions of different NMDAR subtypes.

• Thirty-two EEGs from six cases of Aicardi's syndrome were reviewed. A characteristic EEG pattern was found in all cases. This consists of multifocal epileptiform abnormalities occurring on a burst-suppression pattern showing complete asynchrony between the two hemispheres. This pattern has been described so far only in Aicardi's syndrome. These characteristic EEG features are more readily found early in the course of the disease and occur less frequently six months after from the onset of symptoms, at which time they are often replaced by multiple epileptic foci on a severely disorganized background. The EEG sleep pattern was profoundly altered in all stages of the disease. The EEG is considered a helpful tool in the diagnosis of Aicardi's syndrome.

• To determine the importance of an abnormal EEG in phenylketonuria (PKU), we reviewed 137 EEGs from 48 patients with PKU. Patients were divided into three groups: group 1 (n = 14) had only normal EEGs, group 2 (n = 20) had only abnormal EEGs, and group 3 (n = 14) initially had normal EEGs that later became abnormal. The most common EEG abnormality was focal paroxysmal discharge. Patients in group 2 started treatment at a later age and had a greater frequency of seizures and mental retardation. Phenylalanine levels greater than 20 mg/dL were more often associated with abnormal EEGs. Older patients were more likely to have abnormal EEGs; 78% of the 41 patients who had EEGs at age 6 or older had abnormal records, whereas only 15% of the 26 patients who had EEGs before the age of 6 had abnormal records. Conventionally treated patients with classic PKU and normal EEGs in infancy may have abnormal EEGs when retested later even though they remain on a restricted diet. Although not usually associated with clinical deterioration, abnormal EEGs may unveil the presence of CNS dysfunction even when a child is in satisfactory clinical condition.

• Patients with seizures accompanied by generalized cortical electrodecremental event (CEE) have clusters of clinical spells with tonic, dystonic, or atonic components and involvement of autonomic functions. When electroencephalographically detectable foci are present, they behave in a peculiar way; throughout the entire cluster of seizures focal spiking is reduced in the short interictal periods as well as during each individual seizure with CEE, at which time it is suppressed. Focal firing reappears reinforced at the end of each spell and also at the end of the cluster. These facts suggest that the foci responsible for CEE are deeply located. A complex excitatory-inhibitory feedback probably exists between cortical and subcortical foci. These seizures should be differentiated from similar attacks of nonepileptic or epileptic nature. A correct diagnosis is essential given the different therapeutic implications.

• On a clinical basis the paroxysmal dyskinesias can be classified into two distinct categories—familial and acquired. The former begins in childhood and the dyskinesia may or may not be induced by sudden movements (kinesigenic or nonkinesigenic forms). In the familial kinesigenic form, the movements are brief, usually occur daily, and respond readily to anticonvulsants. This form has an autosomal dominant or recessive mode of inheritance. In the familial nonkinesigenic form, the movements are of longer duration, occur less frequently, and rarely respond to anticonvulsants. This form has a clear autosomal dominant mode of inheritance. The etiology is obscure. The acquired form of paroxysmal dyskinesia has a later onset and is an expression of an underlying neurological or metabolic disease. Some cases of acquired paroxysmal dyskinesia are manifestations of unusual forms of epilepsy. In these cases the differential diagnosis may be extremely difficult and must be based on EEG findings during an ictal episode.