Occurrence of hyperventilation-induced high amplitude rhythmic slowing with altered awareness after successful treatment of typical absence seizures and a network hypothesis.

BACKGROUND: Typical absence seizures (AS) are epileptic phenomena typically appearing in children 4-15 years of age and can be elicited by hyperventilation (HV). Hyperventilation-induced high-amplitude rhythmic slowing (HIHARS) represents a paraphysiological response during HV and may manifest with alteration of awareness (HIHARSAA). To date, HIHARSAA has mostly been described in patients without epilepsy. AIM: To describe five patients with treatment-responsive typical AS who, after becoming seizure free, presented with HIHARSAA. METHODS: By using video-electroencephalographic recording (Video-EEG), we describe differential clinical characteristics and ictal electrophysiological patterns of both typical AS and HIHARSAA. RESULTS: We demonstrate that when HIHARSAA occurs in patients with typical AS there is a temporal window between the two phenomena. This suggests that the presence of typical AS precludes the appearance of HIHARSAA. CONCLUSIONS: We hypothesize that alkalosis and dysfunction of the same neural network are involved in both typical AS and HIHARSAA and that their distinct electroclinic manifestations are due to the involvement of different ion channels. SIGNIFICANCE: A better understanding of the characteristics of typical AS and HIHARSAA and of the role of alkalosis in both, can help avoiding misdiagnosis and identifying more suitable therapies for typical AS.

Epidemiology of multiple sclerosis in the pediatric population of Sardinia, Italy.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Several authors report MS affecting not only young adults but also children and adolescents. Sardinia is one of the regions at the highest risk for MS worldwide in the adult population; to date, no definite data exist on the pediatric population. The aim of this study was to estimate the incidence and prevalence of pediatric MS (pMS) in northern Sardinia. Patients with diagnosis of optic neuritis, myelitis, acute disseminated encephalomyelitis (ADEM), demyelinating disorders, MS, or clinically isolated syndrome (CIS) according to McDonald criteria were enrolled, when disease onset occurred within the range of 0-18 years. From January 1, 2001 to December 31, 2012, 21 cases of pMS and 5 cases of CIS were found in northern Sardinia. The annual mean pMS incidence was 2.85 cases per 100,000 pediatric population, and the annual mean CIS incidence was 0.68 cases per 100,000 pediatric population. The pMS and CIS prevalence computed on 31 December 2012 was 26.92 and 6.41 per 100,000 pediatric population, respectively. CONCLUSION: Our pMS data among Sardinians corroborate the epidemiological scenario described in the adult population being the incidence estimates significantly higher than those reported elsewhere. WHAT IS KNOWN: Sardinia is one of the regions at the highest risk for MS worldwide in the adult population. To date, no definite data exist on the pediatric population. WHAT IS NEW: The pediatric MS incidence in Sardinia is estimated to be significantly higher than those reported elsewhere. The pediatric MS prevalence in Sardinia is among the highest values worldwide.