[Abstract] a Glasgow Coma Scale of 15 at discharge.



Patients with
nonexertional heat stroke often have a poor prognosis and suffer neurological
sequelae. We report a rare case of full neurological recovery in a 77-year-old
woman who fell into a coma with an initial Glasgow Coma Scale of 3 while taking
a bedrock bath. Severe nonexertional heat stroke was quickly diagnosed, and intensive
treatment including a blood transfusion and body temperature management was immediately
provided. Laboratory data showed multi-organ failure, and her
electroencephalogram showed very low amplitude on hospitalization day 6, indicating
a poor prognosis; however, she gradually recovered consciousness, and her
electroencephalogram normalized, showing a Glasgow Coma Scale of 15 at
discharge. This case demonstrated that intensivists should not withhold treatment
from a patient with severe heat stroke on the basis of a poor initial
electroencephalogram result and laboratory data.  132 words

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Nonexertional heat stroke is defined as a
core body temperature exceeding 40 degrees Celsius causing central nervous
system dysfunction. 1 In general, the deeper the coma, the greater the
likelihood of mortality becomes. 2 Few studies were reported regarding heat
stroke caused by bedrock bath compared to sauna. We experienced report here a rare
case of severe nonexertional heat stroke that initially showed an electroencephalogram
(EEG) with very low amplitude (< 10 uV) indicating a poor prognosis, but eventuated in a full recovery. A 77-year-old woman was brought to the emergency department by ambulance after being found with severe disturbance of consciousness and fecal incontinence while taking a bedrock bath. On physical examination, she was in a deep coma with a Glasgow Coma Scale of 3, blood pressure of 93/67 mmHg, heart rate of 175 beats per minute, regular respiratory rate of 24 breaths per minute, and a tympanic temperature of 40.1 degrees Celsius. She had a history of untreated hypertension. A laboratory test revealed increased serum creatinine and creatine kinase at 1.38mg/dL and 1545 IU/L, respectively. A head CT and MRI scan showed no significant lesion. All other examinations including abdominal ultrasonography, transthoracic echocardiography, lumbar puncture, and EEG disclosed no specific abnormalities. The possibility of epilepsy or encephalitis was negligible. After detailed examination, we initiated immediate cooling and intensive care including a blood transfusion and mechanical ventilation in the intensive care unit for the treatment of severe heat stroke. Tracheal intubation and a sedative and analgesic were also administered. Despite intensive medical care, her clinical course was severe as shown in Figure.1. Her initial SOFA score at hospitalization was 8 and reached a peak of 16 on hospital day 4. On hospital day 4, autonomic nervous abnormalities of uncertain origin were found. Hypertensive crisis without counter-regulation of the heart rate followed by consecutive circulatory collapse every 2 hours occurred as shown in Figure 2. The presentation was similar to the "autonomic storm" found in amyotrophic lateral sclerosis, suggesting involvement of the limbic system. 3 This central sympathetic hyperactivity ceased on hospital day 5 without further life-threatening events. On hospital day 5, sedation using midazolam was discontinued. Despite the discontinuation, she remained unconscious for the following 2 days, and her EEG on the day 6 showed very low amplitude (< 10 uV), suggesting an unfavorable neurological prognosis even if death were prevented (Figure 3). As per her family's wishes, treatment was withheld and further attempts at resuscitation were discontinued. However, contrary to our expectations, the patient responded to intensive supportive care. She gradually recovered consciousness from hospital day 8, and was extubated on hospital day 11 with a Glasgow Coma Scale of 15. Her EEG eventually normalized and she was discharged. She had no significant neurological sequelae. Her Mini–Mental State Examination score was 29 at 2 years after discharge.   A bedrock bath is similar to a sauna but differs in the way it heats the body. The bedrock bath does not use water; instead, the bather lies on a flat stone which is heated to around 50 degrees Celsius. The room temperature is maintained at 40-45 degrees Celsius and the humidity is maintained at about 40%, creating what is believed to be a more comfortable environment than a sauna. During a bedrock bath the heated stone emits far infrared rays, which warm the body without steam or water. Although Hannuksela et al. have reported the risks of sauna bathing 4, only one case report in Japanese on nonexertional heat stroke during a bedrock bath exists. 5 Our case demonstrated that falling asleep in a bedrock bath might cause central sympathetic hyperactivity, which sometimes results in sudden death due to circulatory collapse 3 or disseminated intravascular coagulation (DIC). Furthermore, there are few studies focusing on the relationship between heat stroke and EEG. In this case, the duration of the sedation-free time was almost 36 h on hospital day 6. We could have used flumazenil to reverse the sedation, discontinuation period of midazolam injection was sufficient not to affect EEG regardless of the liver dysfunction. 6 Although further studies are needed, our case demonstrated that the prognosis of patients with heat stroke may be unrelated to poor EEG findings, laboratory data, unknown causes of sympathetic hyperactivity, or poor state of consciousness. Careful judgement should therefore be exercised before withholding treatment. Acknowledgements We thank Dr. Toshio Shimizu and Dr. Yasufumi Miyake for their constructive comments and all the staff for their care of the patient and their contributions to this study.   Figure Legends Figure 1. Clinical course from admission to hospital day 11 Despite immediate cooling and intensive care, the patient's clinical course was severe. The initial SOFA score at hospitalization was 8 and reached a peak of 16 on hospital day 4. The patient's consciousness gradually recovered after hospital day 8. The patient was successfully extubated on hospital day 11 with a Glasgow Coma Scale of 15.   CK, creatine kinase IU/L, left axis; ALT, alanine aminotransferase IU/L, left axis; T-bil, total bilirubin mg/dL, right axis, SOFA score (right axis).   Figure 2. Autonomic nervous abnormalities on hospital day 4. Hypertensive crisis without counter-regulation of heart rate followed by consecutive circulatory collapse every two hours was observed.   sBP, systolic blood pressure mmHg; dBP, diastolic blood pressure mmHg; HR, heart rate /min   Figure 3. Electroencephalogram (EEG) on days 6 (A), 9 (B), 21 (C), and 156 (D)Follow-up EEGs normalized in the clinical course. (A) The amplitude of the EEG was lower than 10 microvolts. Note the prominent ECG artifacts. (B) Slight revival of neuronal activity. (C) Background activity showed a diffuse alpha rhythm (not dominant in the occipital region). (D) Alpha attenuation was fully conserved (Arrow head, eye opening). All EEGs used the same scale and were filtered by a time constant of 0.1 sec and high cut filter of 70 Hz.     References 1 Bouchama A, Knochel JP. Heat stroke. N Engl J Med. 2002;346:1978-88. 2 Argaud L, Ferry T, Le QH, Marfisi A, Ciorba D, Achache P, et al. Short- and long-term outcomes of heatstroke following the 2003 heat wave in Lyon, France. Arch Intern Med. 2007;167:2177-83. 3 Shimizu T. Sympathetic hyperactivity and sympathovagal imbalance in amyotrophic lateral sclerosis. Eur Neurol Rev. 2013;8:46-50. 4 Hannuksela ML, Ellahham S. Benefits and risks of sauna bathing. Am J Med. 2001;110:118-26. 5 Sawamoto K, Bunya N, Yoneta S, Takeyama Y. A case of heat stroke occurring while taking a bedrock bath. J Jpn Association for Acute Med. (in Japanese) 2009;20:221-5. 6 Patel SB, Kress JP. Sedation and analgesia in the mechanically ventilated patient. Am J Respir Crit Care Med. 2012;185:486-97.