This study was conducted in accordance with the Declaration of Helsinki. We reviewed the electronic medical records for patients who had HS from 1 January 2016 to 1 March 2022 in our hospital. For all cases from our hospital records, we recorded the patient's gender, age, blood pressure, core temperature (immediately after admission), Glasgow coma scale (GCS) on arrival, DIC score, liver and kidney function, blood coagulation function, blood routine, cardiac indicators, analysis of cerebrospinal fluid (CSF), results of neuroelectrophysiological examination, brain magnetic resonance imaging (MRI), and the clinical prognosis. The same variables were collected from the previously reported cases if available (clinical background, patient characteristics, results of neuroelectrophysiological and laboratory examination, MRI findings, and prognosis). The Barthel index was evaluated to assess daily living ability at 90 days after HS.

For literature research, we reviewed published scientific reports by searching the PubMed database and China National Knowledge Infrastructure (CNKI). Search strategies were developed to find publications containing subject headings and key words (text words) including heat stroke, heat or sun disorder, injury, illness, stress, related, shock, exhaustion; heat stroke; neurology; nervous system; Guillain–Barré syndrome; peripheral neuropathy; and case, cases. Papers included were limited to human subjects and publication types (case reports, case series). Publications of cases that had an exertional component or nonexertional HS (e.g., confined spaces, Bikram Yoga, and electric blankets) were both included in this study. Papers excluded from review were those unrelated to Guillain–Barré syndrome or peripheral neuropathy or where individual patient data were not available.

A 57-year-old man was found unresponsive in a workshop on a hot summer day (ambient temperature 36°C). His core temperature was 42°C within 30 min of admission. He was in deep coma with wide unreactive pupils and without corneal and pharyngeal reflexes. Blood pressure was 95/43 mmHg and the heart rate was 146/min. He developed disseminated intravascular coagulation (DIC), thrombopenia below 1,800 MRD/ml, acute heart/liver/kidney damage, rhabdomyolysis, and metabolic acidosis. He was diagnosed with HS. After 7 days of treatment including hyperbaric oxygen (HBO), correction of electrolyte and acid-base disturbance, antishock, protection of cardiac and hepatorenal function, suppression of excessive gastric acid secretion, etc., his consciousness recovered from coma and his limb muscles had Medical Research Council (MRC) grades 4. But only 1 day later, he complained of fatigue, weakness of limbs, dyspnea, and difficulty in expectoration. He required intensive care and tracheotomy within hours. All limb muscles had MRC grade 0. Facioplegia increased 2 days later. He had no ophthalmoplegia, but having hyporeflexia and stocking glove hypoesthesia for vibratory and cold stimuli. Small ischemic focus in the basal ganglia and cortex was shown through MRI. Protein concentration in CSF was 0.47 g/l at 2 days after tetra paresis and 1.82 g/l 10 days later. White blood cell (WBC) count was 0.60 × 106/L cells/mm3 at 2 days after tetra paresis and 5.4 × 106/L cells/mm3 10 days later. Antibody concentration in the CSF and serum was all normal. Compound motor action potentials were <1 mV in all tested nerves at 10 days after HS. Conduction velocities were below 90% of the lower limit of normal in the bilateral tibial nerve and common peroneal nerves. F responses were missing in both median nerves, ulnar nerves, tibial nerves, and common peroneal nerves. A conduction block was present along the both median nerves (right wrist stimulation amplitude 0.67 mV and left 0.56 mV; right elbow stimulation amplitude 0.45 mV and left 0.58 mV) and ulnar nerves (right wrist stimulation amplitude 0.76 mV and left 0.88 mV; right elbow stimulation amplitude 0.69 mV and left 0.87 mV). The sensory potentials of bilateral tibial nerves and common peroneal nerves were not elicited. The amplitude of the sensory potentials of bilateral median nerves and ulnar nerves was reduced. The patient was diagnosed with AIDP and treated with a 2-day course plasma exchange, intravenous immunoglobulin (IVIG) for 5 days, and then immune-modulating therapy (methylprednisolone). The strength of both upper limbs recovered to MRC grade 1, and the patient was discharged from hospital 29 days after HS. Then, 3 months after HS, upper limb muscles had MRC grade 3 and lower limb muscles had MRC grade 2, which made the patient chair-bound.

A 41-year-old man fainted suddenly with projectile vomiting while working on a hot summer day (ambient temperature 35°C). His core temperature was 42.3°C on admission. He was in light coma with corneal, pharyngeal, and pupillary light reflexes. Tachypnoea had induced hypocapnia. Blood pressure was 92/46 mm Hg and the heart rate was 165/min. He had hepatic and renal dysfunction, inflammatory reaction, myocardial ischemia, and coagulation disorders. No abnormalities were found in brain MRI and he was diagnosed with HS. After 2 days of coma, he was conscious and the MRC grades of his limbs were level 5 (normal). But after 8 more days, he complained of fatigue, myalgia, and arthralgia, and 3 days later, he developed fever (38.9°C), tetraplegia, and dysphagia. He required intensive care within hours. Proximal arm muscles had MRC grades between 2 and 3. All other limb muscles had grade 0 and he developed facioplegia. Protein concentration in CSF was 0.88 g/l and WBC count was 3 × 106/L at 1 day after the onset of tetra paresis. Protein concentration in CSF was 0.62 g/l and WBC count was 1.3 × 106/L at after 2 more days. The concentration of IgG antibody in the CSF was 59 mg/L, and concentration of IgA antibody was 2.55 mg/L at 2 days after the onset of tetra paresis. Compound motor action potentials were <1.5 mV in all tested nerves 14 days after HS. Conduction velocities were below 90% of the lower limit of normal in the bilateral tibial nerves and common peroneal nerves. F responses were missing in both tibial nerves and common peroneal nerves. F responses were decreased in both median nerves and were normal in both ulnar nerves. A conduction block was present along the both median nerves (right wrist stimulation amplitude 1.85 mV and left 1.86 mV; right elbow stimulation amplitude 1.42 mV and left 1.42 mV) and tibial nerves (right ankle stimulation amplitude 0.42 mV and left 0.46 μV; right knee stimulation amplitude 0.48 mV and left 0.62 mV). The sensory potentials of the bilateral tibial nerves and common peroneal nerves were not elicited. The patient was diagnosed with AIDP and treated with IVIG for 5 days and then immune-modulating therapy (methylprednisolone). The strength of the limbs recovered to MRC grade 3, and the patient was recovered from facioplegia 32 days after HS. The patient was relieved from tracheotomy and could stand up with walking aid 90 days after HS.

A 56-year-old man felt dizziness and fatigue while working in a hot environment (ambient temperature 33°C). Immediately, the patient developed blurred consciousness, irritability, and progressed to coma and accompanied by great sweating. He was admitted to emergency room immediately. His core temperature was 42°C, with a blood pressure of 87/36 mm Hg and the pulse rate of 164/min. He was in a deep comatose state, hepatorenal dysfunction, hypokalemia, elevated inflammatory reaction, myocardial ischemia associated with increased myocardial enzymes, coagulation disorders, and rhabdomyolysis. No abnormalities were found in brain MRI. He was diagnosed with HS and was treated by cooling, antishock, and intubation. He was conscious after 10 days of coma. The strength of his upper limbs had MRC grade 1 and the lower limb muscles had grade 3. His hepatorenal dysfunction, inflammatory reaction, myocardial ischemia, and coagulation disorders were alleviated after 12 days. But after 6 more days, the patient developed drowsiness, tetraplegia with MRC grade 0 of the muscle strength, dys-expectoration, and required tracheotomy. Protein concentration in CSF was 1.09 g/l and WBC count was 3.4 × 106/L at 3 days after tetra paresis. Immunoglobulin in CSF and serum was normal. Compound motor action potentials were <1 mV in all tested nerves at day 18. Conduction velocities were below 90% of the low limit of the normal value in both median nerves and ulnar nerves. F responses were missing in tibial nerves, ulnar nerves, and common peroneal nerves. A conduction block was present along the both median nerves (right wrist stimulation amplitude 0.78 mV and left 0.56 μV; right elbow stimulation amplitude 0.43 mV and left 0.51 mV) and tibial nerves (right ankle stimulation amplitude 0.53 mV and left 0.55 mV; right knee stimulation amplitude 0.35 mV and left 0.39 mV). The sensory potentials of the bilateral tibial nerves, ulnar nerves, median nerves, and common peroneal nerves were not elicited. The patient was diagnosed with AIDP at 19 days after HS and treated with a 5-day course IVIG and then immune-modulating therapy (methylprednisolone). He was sober 21 days after HS and his upper limbs had MRC grade 1 at 42 days after HS. His upper limb strength had MRC grade 2 and lower limb strength had MRC grade 4 at 90 days after HS.

To our knowledge, the most cases of GBS induced by HS have been reported in this study in the recent 5 years. Clinicians should pay attention to heat stroke patients with sustained coma. When extremity weakness, tetraplegia, and dysphagia develop after the patient recover consciousness, early, exact, and timely diagnosis and treatment should be performed, to accelerate recovery and improve prognosis.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.

XXN: data curation and writing-original draft preparation. CLW: data curation. YQG: methodology. ZFL: writing and reviewing and editing. All authors contributed to the article and approved the submitted version.

This work was supported by grants from the National Natural Science Foundation of China [No. 82072143], Natural Science Foundation of Guangdong Province of China [No. 2021A1515010170], the PLA Logistics Research Project of China [18CXZ030, BLJ20J006], and the PLA Medical Science and Technology Youth Development Programme [21QNPY122].

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

The authors would like to extend their heartfelt thanks to Prof. Lei Su for his insightful guidance in the course of this research.