Temperature variation in the 24 hours before the initial symptoms of stroke

Abstract

A few studies have performed to evaluate the temperature variation influences over on the stroke rates in Brazil. Method: 176 medical records of inpatients were analyzed after having had a stroke between 2004 and 2006 at Hospital Israelita Albert Einstein. The temperature preceding the occurrence of the symptoms was recorded, as well as the temperature 6, 12 and 24 hours before the symptoms in 6 different weather substations, closest to their houses in São Paulo. results: Strokes occurred more frequently after a variation of 3ºC between 6 and 24 hours before the symptoms. There were most hospitalizations between 23-24ºC. conclusion: Incidence of stroke on these patients was increased after a variation of 3º Celsius within 24 hours before the ictus. The temperature variations could be an important factor in the occurrence of strokes in this population. Key words: stroke, temperature, cardiovascular risk, seasonal.Variação da temperatura nas 24 horas anteriores aos sintomas iniciais do acidente vascular cerebral resuMo Poucos trabalhos têm estudado a variação sazonal e de temperatura em acidente vascular cerebral (AVC) no Brasil. Método: Foram analisados 176 registros de pacientes com AVC no Hospital Israelita Albert Einstein entre 2004 e 2006. Foram anotadas as temperaturas ambientes do início dos sintomas, bem como as temperaturas de 6, 12 e 24 horas antes dos sintomas, em 6 diferentes subestações metereológicas mais próximas da casa do paciente em São Paulo. resultados: Houve aumento da incidência do AVC com a variação de 3ºC entre 6 e 24 horas antes do início dos sintomas. Houve um pico de internação entre 23-24ºC. conclusão: A variação de temperatura de 3ºC nas 24 horas que antecederam o início dos sintomas pode ter sido um fator importante na ocorrência do AVC. Palavras-chave: acidente vascular cerebral, temperatura, risco cardiovascular, sazonal. The correlation between strokes and seasonal variations have been studied in various places [1][2][3][4][5][6][7][8] . Some studies around the world have reported an increase of incidence, mortality, and stroke hospitalization during the coldest months of winter.The authors suggest that the temperature variations may trigger responses of vasoconstriction with increase in cardiovascular events. However, the understanding of the relation between changes of weather and cardiovascular events is limited 9-13 . The variation of temperatures before the occurrence of ictus has not been frequently observed. The change in temperature before a stroke could has play a more important role than the season it self. Authors show that the incidence of hemorrhagic stroke (HS) was higher on those days during which the temperature varied significantly 12 .

The Effect of Season and Temperature Variation on Hospital Admissions for Incident Stroke Events in Maputo, Mozambique

“…Low temperatures, on the other hand, were shown to induce vasoconstriction, increased blood pressure, enhanced platelet aggregation, sympathetic nervous system activation, and increased levels of C-reactive protein, fibrinogen, and activated VII factor. 31,32 Our results also showed that temperature variations are more likely to affect stroke incidence than absolute temperature which is in accordance with previous evidence from Brazil, 3 Germany, 13 Japan, 33 Korea 4 and Portugal. 34 The clinicians' perception of increased incidence of stroke after sudden drops in temperature is in accordance with our results, and this effect was shown to be more pronounced with minimum temperature variations than with maximum temperature changes, despite the latter are more pronounced.…”

“…3-6 Despite the evidence is conflicting, some studies showed a higher frequency of stroke in the colder months, 5,7-12 and sudden temperature changes in the days before the event, both downward and upward, were shown to influence the risk of stroke. 3,4,13 However, most of the previous investigations were conducted in temperate climate settings of the northern hemisphere and describing these patterns of variation in tropical and subtropical climates may contribute to understand if high temperatures, together with high humidity, result in different biological consequences. 14,15 …”

Innovative Approaches Helpful to Enhance Knowledge on Weather-Related Stroke Events Over a Wide Geographical Area and a Large Population

“…For this reason, it is also plausible that other biological reactions to cold conditions might contribute to explain the underlying pathophysiology responsible for this relationship. Other authors 25 recently investigated the potential rule played by short-term temperature changes and found that a variation of 3°C within 24 hours before the ictus increased the incidence of stroke. This value was found similar to the estimated break points (critical thresholds) identified in this study, in which a characteristic "J-shaped" association between ⌬T 850hPa and all stroke hospitalizations was observed; a lower critical ⌬T 850hPa threshold in subjects Ն65 years of age (1.3°C) than in the total sample (2.6°C) was observed.…”

Meteorological Variables Associated with Stroke

“…For example, every 1°C increase in mean temperature during the preceding 24 hours was associated with a 2.1% rise in hospital admissions for IS [ 6 ]. Hospitalizations for both hemorrhagic and ischemic strokes were low when ambient temperature at 6, 12, and 24 hours prior to initial symptoms was <20°C and peaked at temperatures between 23°C and 24°C [ 17 ]. Mortality due to IS correlated with a 1°C increase in mean temperature, with an estimated percentage change in mortality above a threshold ranging from 2.3% and 5.4%, although risk decreased after adjustment for confounders [ 18 ].…”

“…For cases of primary ICH, sudden increased risk of hospitalization occurred when changes in temperature exceeded ±5°C [ 20 ]. Coelho et al (2010) found that, for both hemorrhagic and ischemic stroke, during the 24 hours before the event almost all patients experienced initial stroke symptoms within a comfortable temperature range but after a change of 3°C [ 17 ]. Days showing clusters of SAH differed significantly in maximum difference in daily temperature compared with noncluster days [ 4 ], and in a 7-day lag analysis, a decreasing change in maximum temperature was associated with an increase in stroke [ 21 ].…”