Winter wheat and barley varieties require an extended exposure to low temperatures to accelerate flowering (vernalization), whereas spring varieties do not have this requirement. In this study, we show that in these species, the vernalization gene VRN3 is linked completely to a gene similar to Arabidopsis FLOWERING LOCUS T (FT).
Ictal hypoxemia has been reported in small series of cases and may contribute to sudden unexpected death in epilepsy (SUDEP). We sought to determine the incidence and severity of ictal hypoxemia in patients with localization-related epilepsy undergoing in-patient video-EEG telemetry. We examined whether seizure-associated oxygen desaturation was a consequence of hypoventilation and whether factors such as seizure localization and lateralization, seizure duration, contralateral spread of seizures, patient position at seizure onset and body mass index influenced ictal-related hypoxemia. A total of 304 seizures with accompanying oxygen saturation data were recorded in 56 consecutive patients with intractable localization-related epilepsy; 51 of 304 seizures progressed to generalized convulsions. Pulse oximetry showed oxygen desaturations below 90% in 101 (33.2%) of all seizures with or without secondary generalization, with 31 (10.2%) seizures accompanied by desaturations below 80% and 11 (3.6%) seizures below 70%. The mean duration of desaturation below 90% was 69.2 +/- 65.2 s (47; 6-327). The mean oxygen saturation nadir following secondary generalization was 75.4% +/- 11.4% (77%; 42-100%). Desaturations below 90% were significantly correlated with seizure localization [P = 0.005; odds ratio (OR) of temporal versus extratemporal = 5.202; 95% CI = (1.665, 16.257)], seizure lateralization [P = 0.001; OR of right versus left = 2.098; 95% CI = (1.078, 4.085)], contralateral spread of seizures [P = 0.028; OR of contralateral spread versus no spread = 2.591; 95% CI = (1.112, 6.039)] and gender [P = 0.048; OR of female versus male = 0.422; 95% CI = (0.179, 0.994)]. In the subset of 253 partial seizures without secondary generalized convulsions, 34.8% of seizures had desaturations below 90%, 31.8% had desaturations below 80% and 12.5% had desaturations below 70%. The degree of desaturation was significantly correlated with seizure duration (P = 0.001) and with electrographic evidence of seizure spread to the contralateral hemisphere (P = 0.003). Central apnoeas or hypopnoeas occurred with 50% of 100 seizures. Mixed or obstructive apnoeas occurred with 9% of these seizures. End-tidal carbon dioxide (ETCO2) was recorded in seven patients (19 seizures). The mean increase in ETCO2 from preictal baseline was 18.6 +/- 17.7 mm Hg (13.2; 2.8-77.8). In these 19 seizures, all oxygen desaturations below 85% were accompanied by an increase in ETCO2. Ictal hypoxemia occurs often in patients with localization-related epilepsy and may be pronounced and prolonged; even with seizures that do not progress to generalized convulsions. Oxygen desaturations are accompanied by increases in ETCO2, supporting the assumption that ictal oxygen desaturation is a consequence of hypoventilation. Ictal hypoxemia and hypercapnia may contribute to SUDEP.
Purpose Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related mortality. Seizure-related respiratory dysfunction (RD), the duration of post-ictal generalized EEG suppression (PGES) and duration of postictal immobility (PI) may be important in the pathophysiology of SUDEP. Peri-ictal interventions may reduce the risk of SUDEP. Methods We assessed the impact of peri-ictal nursing interventions on RD, PGES and PI duration in patients with localization-related epilepsy and secondarily generalized convulsions (GC) recorded during video-EEG telemetry in the epilepsy monitoring unit. Video-EEG data were retrospectively reviewed. Interventions including administration of supplemental oxygen, oropharyngeal suction, and patient repositioning were evaluated. Interventions were performed based on nursing clinical judgment at the bedside and were not randomized. The two-sided Wilcoxon rank-sum test was used to compare GC with and those without intervention. Robust simple linear regression was used to assess the association between timing of intervention and duration of hypoxemia (SaO2 <90%), PGES and PI using data from only the first GC for each patient. Key Findings Data from 39 patients with 105 GC were analyzed. PGES >2 seconds occurred following 31 GC in 16 patients. There were 21 GC with no intervention (NOINT) and 84 GC with interventions (INT). In the INT group, the duration of hypoxemia was shorter (P=0.0014) when intervention occurred before hypoxemia onset (mean duration 53.1 sec) than when intervention was delayed (mean duration 132.42 sec). Linear regression indicated that in GC with nursing interventions, earlier intervention was associated with shorter duration of hypoxemia (p<0.0001) and shorter duration of PGES (p=0.0012). Seizure duration (p <0.0001) and convulsion duration (p=0.0457) were shorter with earlier intervention. PI duration was longer for GC with PGES than GC without PGES (p<0.0001). The mean delay to first active non-respiratory movement following GC with PGES was 251.96 sec and for GC without PGES was 66.06 sec. The duration of PI was positively associated with lower SaO2 nadir (p=0.003) and longer duration of oxygen desaturation (p=0.0026). There was no association of between PI duration and seizure duration (p=0.773), between PI duration and PGES duration (p=0.758), or between PI duration and the timing of first intervention relative to seizure onset (p=0.823). PGES did not occur in the NOINT group. The mean duration of desaturation was longer (110.9 seconds versus 49.9 seconds) (P<0.0001), mean SaO2 nadir was lower (72.8% v 79.7%) (p=0.0086) and mean end-tidal CO2 was higher (58.6 mmHg v 50.3 mmHg) (p=0.0359) in the INT group compared with the NOINT group. The duration of the seizure or of the convulsive component was not significantly different between the INT and NOINT groups. Significance Early peri-ictal nursing intervention was associated with reduced duration of RD, and reduced duration of PGES. These findings suggest the possibility that such inte...
Summary Ictal respiratory dysfunction occurs in patients with epilepsy and may contribute to sudden unexplained death in epilepsy (SUDEP). Fluoxetine reverses respiratory arrest in a mouse model of epilepsy, suggesting that selective serotonin reuptake inhibitors (SSRIs) may reduce ictal respiratory dysfunction. Video–electroencephalography (EEG) and pulse oximetry data from 496 seizures in 73 consecutive patients with partial epilepsy was reviewed, including 87 seizures in 16 patients taking SSRIs (SSRI+) and 409 seizures in 57 patients not taking SSRIs (SSRI−). The proportion of ictal‐related oxygen desaturation <85% with partial seizures without secondary convulsions in SSRI+ patients was reduced relative to SSRI− patients (p = 0.011). There was no statistically significant difference in ictal oxygen desaturation for secondarily generalized convulsions. SSRIs are associated with reduced likelihood of ictal oxygen desaturation in patients with partial seizures.
SUMMARYPurpose: The rate of sudden unexpected death in epilepsy (SUDEP) approaches 9 per 1,000 patient-years in patients with refractory epilepsy. Respiratory causes are implicated in SUDEP. We reported that ictal hypoxemia occurs in one-third of seizures in localization-related epilepsy. We now report on respiratory changes in the ictal/ postictal period including changes in end-tidal CO 2 (ETCO 2 ) that correlate directly with alveolar CO 2 , allowing a precise evaluation of seizure-related respiratory disturbances. Methods: One hundred eighty-seven seizures were recorded in 33 patients with localization-related epilepsy, with or without secondarily generalized convulsions, undergoing video-electroencephalography (EEG) telemetry with recording of respiratory data. Results: The ictal/postictal ETCO 2 increase from baseline was 14 ± 11 mm Hg (11, )1 to 50) [mean ± standard deviation (SD) (median, range)]. ETCO 2 peak was at or above 50 mm Hg with 35 of 94 seizures, 60 mm Hg with 15, and 70 mm Hg with five seizures. Eleven of the 33 patients had seizures with ETCO 2 elevation above 50 mm Hg. The duration of ictal/postictal ETCO 2 increase above baseline was 424 ± 807 s (154, 4 to 6225). The duration of ictal apnea was 49 ± 46 s (31, 6-222); most ictal apneic events were central. Oxygen desaturation to 60% or less occurred with 10 seizures, including five that did not progress to generalized convulsions. Respiratory rate and amplitude increased postictally. The peak ictal ETCO 2 change and duration of change were not associated with apnea duration or seizure duration. Peak ETCO 2 change was significantly associated with contralateral seizure spread. Conclusions: Severe and prolonged increases in ETCO 2 occur with seizures. Postictally, respiratory effort is not impaired. Ictally triggered ventilation-perfusion inequality from pulmonary shunting or transient neurogenic pulmonary edema may account for these findings. KEY WORDS: Sudden unexpected death in epilepsy, Hypercapnia, Hypoxemia, Seizure, Localization-related epilepsy.Sudden unexpected death in epilepsy (SUDEP) has an incidence of 0.09-9 per 1,000 patient years, with the highest incidence in patients with refractory epilepsy (Tomson et al., 2008). Both cardiac and respiratory mechanisms are implicated in SUDEP (Surges et al., 2009). Seizures are associated with hypoxemia (Hewertson et al., 1996;Nashef et al., 1996;Blum et al., 2000;Bateman et al., 2008). We demonstrated a high incidence of ictal/postictal hypoxemia in patients with localization-related epilepsy undergoing inpatient video-EEG telemetry (VET) (Bateman et al., 2008). Ictal hypoxemia may be severe and prolonged in partial-onset seizures (Bateman et al., 2008). Respiratory changes in the ictal and postictal period are not well characterized. End-tidal CO 2 (ETCO 2 ) measurements correlate directly with changes in alveolar P CO2 and may, therefore, allow a precise evaluation of seizure-related respiratory disturbances. In contrast, oxygen saturation (SaO 2 ) recorded by digital pulse oximetry has ...
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