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.

SPECT imaging of cerebral blood flow changes induced by acute trigeminal nerve stimulation in drug-resistant epilepsy. A pilot study.

OBJECTIVE: To explore the cortical areas targeted by acute transcutaneous trigeminal nerve stimulation (TNS) in patients with drug-resistant epilepsy (DRE) using single photon emission computed tomography (SPECT). METHODS: Ten patients with DRE underwent brain SPECT at baseline and immediately after a 20-minute TNS (0.25 ms; 120 Hz; 30 s ON and 30 s OFF) applied bilaterally to the infraorbital nerve. The French Color Standard International Scale was used for qualitative analyses and z-scores were used to calculate the Odds Ratio (OR). RESULTS: At baseline global hypoperfusion (mainly in temporo-mesial, temporo-parietal and fronto-temporal and temporo-occipital areas) was detected in all patients. Following TNS, a global increase in cortical tracer uptake and a significant decrease in median hypoperfusion score were observed. A significant effect favoring a general TNS-induced increase in cortical perfusion (OR = 4.96; p = 0.0005) was detected in 70% of cases, with significant effects in the limbic (p = 0.003) and temporal (p = 0.003) lobes. Quantitative analyses of z-scores confirmed significant TNS-induced increases in perfusion in the temporal (+0.59 SDs; p = 0.001), and limbic (+0.43 SDs; p = 0.03) lobes. CONCLUSION: Short-term TNS is followed a global increase in cortical perfusion, namely in the temporal and limbic lobes. SIGNIFICANCE: The TNS-induced perfusion increase may reflect neurons' activity changes in cortical areas implicated in the epilepsy network.

Seasonal fluctuation of multiple sclerosis births in Sardinia.

Study results from different geographical areas provide some circumstantial evidence that, when compared with the general population, people who later in life develop multiple sclerosis (MS) have a pattern of birth excess numbers in spring and late summer, which may disclose an association with MS-predisposing environmental agents. To identify the presence of season-related cluster of MS birth in Sardinia we have designed a case-control study in the province of Sassari, Northern Sardinia, insular Italy, an area at very-high and increasing risk for MS. Mean birth incidence rate of people with MS (810 cases) on a three-and six-months basis were compared with that of two control populations: the MS unaffected siblings (1069), sharing genetic material with patients, and a representative number of births (247,612) of the general population of the study area. We found that the birth in months peaking in spring significantly represents one risk factor for future MS development. This seasonal deviation of MS births reveals an intriguing epidemiological overlap with common environmental agents, which may open a new scenario of hypothetical explanations for environmental factors perhaps affecting the CNS at the crucial time of myelination or shaping the newborn immune system.