Sequelae in the central nervous system secondary to heat-related illness: an analysis of the Heatstroke STUDY 2006 and Heatstroke STUDY 2008

• Published in: Nihon Kyukyu Igakukai Zasshi 2011/07/15, Vol.22(7), pp.312-318
• Main Authors: Nakamura, Shunsuke, Miyake, Yasufumi, Dohi, Kenji, Fukuda, Kenichiro, Tanaka, Kotaro, Morikawa, Kentaro, Aruga, Tohru
• Format: Article
• Language: eng ; jpn
• Subjects: cognitive impairment; cooling; swallowing disturbance
• ISSN: 0915-924X; 1883-3772
• DOI: 10.3893/jjaam.22.312

Background: Although some case reports have previously demonstrated the neurological sequelae of heatstroke, the clinical findings associated with its pathogenesis have not yet been fully investigated. Objective: To examine the risk factors for central nervous system damage secondary to heatstroke. Methods: This study analyzed the medical data of patients with neurological sequelae of heatstroke that were extracted from the Heatstroke STUDY 2006 and Heatstroke STUDY 2008, which were carried out by the Heatstroke Surveillance Committee of the Japanese Association for Acute Medicine. We compared these data with those of patients without neurological sequelae (control group), and their severity of heatstroke was categorized as Class III, except for fatal cases. Results: Twenty-two of 1,441 cases (1.5%) with heat-related illnesses manifested sequelae in the central nervous system. These findings included cognitive impairment (15 cases), swallowing disturbance (6 cases), cerebellar ataxia (2 cases), aphasia (1 case) and vegetative state (1 case). The mean age and male-female ratio of patients with sequelae of heatstroke was 62.6 years, and 13 to 9, respectively, while those of the 286 patients in a control group was 55.4 years, and 213 to 72 (unknown 1), respectively. The clinical findings on arrival at the hospital, showed that a decrease in systolic arterial blood pressure (90 mmHg or less) and tachycardia (120 beats/minute or more) were observed more frequently in the patients with sequelae than those in a control group, but a comparison of the observed values showed no significant difference between the groups. On the other hand, significant differences were observed in the total scores on the Glasgow coma scale (GCS), body temperature, the value of base excess (BE) in arterial blood gas on arrival, and the cooling time from start to attaining 38 °C in the hospital (p=0.001, p=0.004, p=0.006, p=0.010, respectively). Conclusion: Heatstroke patients presenting with severe disturbance of consciousness on arrival at the hospital, higher body temperature or low BE values were more likely to experience sequelae in the central nervous system, and they were treated for a longer cooling time to achieve the target temperature. It is important to provide aggressive cooling, intensive care and neuroprotective therapy as soon as possible, in order to avoid the neurological sequelae of heatstroke.