Neurophysiological Findings in Neuronal Ceroid Lipofuscinoses.

Neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of neurodegenerative diseases, characterized by progressive cerebral atrophy due to lysosomal storage disorder. Common clinical features include epileptic seizures, progressive cognitive and motor decline, and visual failure, which occur over different time courses according to subtypes. During the latest years, many advances have been done in the field of targeted treatments, and in the next future, gene therapies and enzyme replacement treatments may be available for several NCL variants. Considering that there is rapid disease progression in NCLs, an early diagnosis is crucial, and neurophysiological features might have a key role for this purpose. Across the different subtypes of NCLs, electroencephalogram (EEG) is characterized by a progressive deterioration of cerebral activity with slowing of background activity and disappearance of spindles during sleep. Some types of heterogeneous abnormalities, diffuse or focal, prevalent over temporal and occipital regions, are described in many NCL variants. Photoparoxysmal response to low-frequency intermittent photic stimulation (IPS) is a typical EEG finding, mostly described in CLN2, CLN5, and CLN6 diseases. Visual evoked potentials (VEPs) allow to monitor the visual functions, and the lack of response at electroretinogram (ERG) reflects retinal neurodegeneration. Taken together, EEG, VEPs, and ERG may represent essential tools toward an early diagnosis of NCLs.

Transient infant movements (TIM): frequent infant non-pathological developmental motor phenomena.

Lombroso and Fejerman, in 1977, described non-epileptic movements in normal infants and named them "benign myoclonus of early infancy", which were recently relabelled by Fernandez-Alvarez as "benign polymorphous movement disorder of infancy" (BPMDI). The focus of our study was to describe, categorize and point out the peculiar clinical representations of these heterogeneous phenomena through our video footage, particularly to those less experienced in paediatric neurology. We included all infants with a video-EEG performed at our unit or a home video recording of "Fejerman-Lombroso", "benign myoclonus of early infancy", "shuddering attacks" or "paroxysmal non-epileptic movements". Twenty-one children were selected. Age at onset ranged between two and 13 months, age at disappearance ranged between seven and 16 months, age at recording ranged between four and 16 months, and duration of the phenomena ranged between two weeks and 19 months. In total, 85% infants had normal neurodevelopment at onset and follow-up (mean follow-up: 31.47 months) and 15% presented with neuropsychological or neurosensory deficits. We distinguished four different patterns of movements: movement of the head in 50%, shuddering attacks in 30%, tonic brief contractions of the trunk and limbs in 10%, and elevation of the shoulders in 10%. These motor phenomena do not affect neurological status and are not associated with developmental delay. Considering that clinical interpretation may be challenging, especially relative to epileptic seizures, we present an explanatory video of these characteristic events. We also propose a new definition that is simple to remember: "transient infant movements" (TIM).