Cryptogenic Recurrent Spontaneous Epidural Hematoma: A Case Report and Literature Review

Min Xu The Third People's Hospital of Yancheng, Yancheng Ya Xue The Third People's Hospital of Yancheng, Yancheng Xiaofeng Chao The Third People's Hospital of Yancheng, Yancheng Zhenglou Chen The Third People's Hospital of Yancheng, Yancheng Yunjiang Wang The Third People's Hospital of Yancheng, Yancheng Xuqi Huo The Third People's Hospital of Yancheng, Yancheng Xiang Ji The Third People's Hospital of Yancheng, Yancheng Hongshen Wang (  2724618771@qq.com ) The Third People's Hospital of Yancheng, Yancheng


Introduction
Intracranial epidural hematoma (EDH) is a hematoma that occurs between the inner plate of the skull and the dura mater, which accounts for about 30% of traumatic intracranial hematoma. EDH is mainly caused by skull fracture after head violence action, which induces hemorrhage by tearing meningeal arteries, veins, and venous sinuses. In contrast, spontaneous EDH is rare and mostly occurs due to adjacent infective pathologies, hematological system diseases, immune system diseases, vascular malformations, metastasis to the skull, etc.
Cryptogenic spontaneous EDH without speci c underlying disease is extremely rarer in this category. (1,2) The unidenti ed primary causes may lead to recurrent episodes of EDH, resulting in severe neurological dysfunction. In this study, we reported a case of cryptogenic recurrent spontaneous EDH (three times) in a 22-year-old woman who received three surgical procedures and nally achieved satisfactory outcomes.
Literature focused on the underlying mechanism of spontaneous EDH was further reviewed.

Case Presentation First EDH
A 22-year-old female was admitted with a blunt headache 1 hour after intercourse. On general physical examination, the consciousness was clear, and the speech was uent. There was no obvious swelling or injury on the head or face. Neurologic specialist physical examination revealed that the Glasgow Coma Scale (GCS) score was 15 (eye opening, 4; motor responsiveness, 6; verbal performance 5). There were no obvious positive signs in the nervous system except headache and dizziness. Emergent nonenhanced computed tomography (CT) scan (each layer with 5-mm-thick) revealed left temporoparietal EDH (the inner and outer diameter: 3cm, the maximum diameter: >10cm, the upper and lower diameter: 7.5 cm) with a rightward midline shift of 1cm. Bone window imaging con rmed no fracture line ( Figure   1A). Preoperative coagulation tests showed that all coagulation parameters were within the normal range (Table 1). Past medical history suggested that the patient had undergone medical abortion 1 month ago, and the speci c drug is unknown.
During preoperative preparation, the patient became increasingly unconscious and agitated.
Before anesthesia, The GCS score was 11 (eye opening, 2; motor responsiveness, 5; verbal performance, 4). Bilateral pupils were equiround with a diameter of 3mm and had light re ection. Two hours after admission, the left temporo-occipital EDH was cleared under general anesthesia in the emergency operating room. No signi cant fracture lines or EDH responsible vessels were found during the operation. The intraoperative blood loss was about 300ml, and no blood transfusion was performed.

Second EDH
After the rst operation, the patient's right pupil was dilated with a diameter of 5.0mm, and light re ection disappeared, while the left pupil diameter was 3.0mm, and light re ection was retarded. Immediate CT examination showed right temporo-occipital EDH (the inner and outer diameter: 3cm, the maximum diameter: >10cm, the upper and lower diameter: 8.5 cm) with a leftward midline shift of 1cm ( Figure   1B). The right temporo-occipital EDH was removed immediately under general anesthesia.
Decompression with ap removal was performed considering preoperative cerebral hernia and high intraoperative intracranial pressure (ICP). No signi cant fracture lines or EDH responsible vessels were found during the operation. The intraoperative blood loss was about 300ml. During the operation, 3U red blood cells and 625ml plasma were transfused.

Third EDH
After the second operation, the patient's right pupil was retracted with a diameter of 3.5mm, and light re ection was retarded. The third immediate CT examination showed bilateral frontal EDH (the inner and outer diameter of the right frontal part: 3.5cm, the hematoma volume: >30ml; the inner and outer diameter of the left frontal part: >2cm, the hematoma volume: 20ml) ( Figure 1C). Bilateral frontal EDH removal was continued in the emergency operating room. As before, no fracture line or EDH responsible vessels were found during the operation. The intraoperative blood loss was about 350ml, and 200ml of plasma was transfused.
After anesthesia resuscitation, the patient resumed spontaneous breathing and regained consciousness. The GCS score was 14 (eye opening, 3; motor responsiveness, 6; verbal performance, 5). The postoperative CT scan showed satisfactory hematoma clearance, and the midline did not shift ( Figure  1D). The patient was discharged two weeks after surgery with a mRS score of 0. There was no signi cant abnormality in the CTA examination in the outpatient clinic 6 months after the operation (Figure 2), and the mRS score was 0. (1) When patients suffer from persistent irritability accompanied by acute hyperventilation, hypocapnia, and intracranial alkalosis will cause dramatic contraction of the arterial vessels, resulting in decreased cerebral blood ow. These physiological reactions eventually decrease ICP. The dissection of the dura and skull increases the accumulation of microbleeds and eventually forms the cryptogenic spontaneous EDH. (1,4) In our case, we noticed that the patient's rst EDH occurred one hour after intercourse, so we speculated that the underlying mechanism might be similar to the above hypothesis, that is, an intense physiological reaction cause a sharp drop in ICP and eventually leads to the dissection of the dura from the skull.
Unfortunately, the patient experienced another two consecutive EDH at different sites during the acute phase after the rst operation. The underlying mechanism of the recurrent EDH may be the sharp drop in ICP due to removal of hematoma and dura dissection due to brain tissue displacement. In addition, the dura mater of young people does not adhere closely to the skull, and it may be easier to peel off than the elderly.
Spontaneous EDH with speci c underlying disease (secondary) Infectious diseases such as periodontitis, maxillary sinusitis infect the meningeal arteries and vessels between skull diploe by retrograde infection, leading to vascular in ammation changes. On the one hand, accumulation of in ammatory exudate, pus, and air in the epidural space may cause separation of the dura from the skull. On the other hand, the in ltrating effects of in ammation lead to thinning and increased permeability of the diploe vessel wall, resulting in a breakthrough hematoma in the epidural space.(5-7) Dural arteriovenous malformations have been reported as a possible cause of EDH.(8) Chen et al. reported a case of spontaneous EDH caused by Langerhan cell histiocytosis (LCH), which was mainly due to osteolytic changes in the skull.(9) Over 20 cases of spontaneous EDH caused by sickle cell disease (SCD) have been reported in previous studies. The main mechanism was thought to be the rapid proliferation and expansion of bone marrow tissue (hematopoietic), which destroys the normal anatomical structure of the skull.(10) Some brain metastasis (BMS) could invade the dura mater and destroy the adjacent bone, and even cause coagulation dysfunction, ultimately leading to the occurrence of EDH. (11)(12)(13) Complement activation and immune complex deposition in the vascular wall are also involved in the onset of spontaneous EDH.(14) These substances will increase the permeability of the blood-brain barrier (BBB) and then stimulate vascular endothelial cells through in ammatory cytokines or autoantibodies. Causes immune injury, including cerebral cortex atrophy, cerebral hemorrhage, cerebral infarction, and intracranial arteriovenous multiple sclerosis.

Conclusion
Cryptogenic spontaneous EDH is rare. EDH should be investigated when a young patient develops headaches and signs of increased ICP after emotional hyperactivity or hyperventilation. If early diagnosis and surgical decompression can be carried out in time, the prognosis is satisfactory.