Intraspinal Epidural Hematoma Caused By Acupuncture Mimicking An Intraspinal Synovial Cyst: A Case Report

Background Intraspinal hematoma is a rare complication of acupuncture. A few cases of subdural hematoma or epidural hematoma have been reported, with most of them in a fusiform shape, making the hematomas easy to identify on magnetic resonance imaging (MRI) scans. Case presentation A 49-year-old man presented with back pain that radiated into his lower limb that had appeared during acupuncture of his back. After admission, MRI was performed and indicated an L5/S1 intraspinal mass that had an oval shape, resembling an intraspinal cyst. The patient underwent surgery to remove the mass, which was conrmed to be a hematoma. Conclusion Intraspinal hematomas appear with various intensity signals and shapes on MRI, making its differential diagnosis dicult. A carefully medical history review (to determine if the pain derives from a puncture-type treatment or an injury) and surgical exploration may be helpful for identifying this condition.

Background Intraspinal hematoma is a rare complication of acupuncture. A few cases of subdural hematoma or epidural hematoma have been reported, with most of them in a fusiform shape, making the hematomas easy to identify on magnetic resonance imaging (MRI) scans.
Case presentation A 49-year-old man presented with back pain that radiated into his lower limb that had appeared during acupuncture of his back. After admission, MRI was performed and indicated an L5/S1 intraspinal mass that had an oval shape, resembling an intraspinal cyst. The patient underwent surgery to remove the mass, which was con rmed to be a hematoma.
Conclusion Intraspinal hematomas appear with various intensity signals and shapes on MRI, making its differential diagnosis di cult. A carefully medical history review (to determine if the pain derives from a puncture-type treatment or an injury) and surgical exploration may be helpful for identifying this condition.

Background
Two studies [1,2] have reviewed the literature on spinal hematomas caused by acupuncture. There were in all 7cases of epidural hematoma and 1case of subdural hematoma. All the patients developed nerve dysfunction a few hours to a few days after the acupuncture procedures, the longest time from the acupuncture to the time point of symptoms was one week, the patient formed Bacterial Meningitis and diagnosed by MRI scan [3]. Due to the short time of symptom after acupuncture treatment and the typical fusiform shape of hematomas on MRI scan, the diagnosis of intraspinal hematoma was easy to made.

Case Presentation
A 49-year-old man presented with a history of having undergone acupuncture treatment at another institution. During the acupuncture, he had experienced sudden, acute back pain that radiated into his left leg. The severe back pain continued for about a month following the acupuncture treatment, whereupon he concluded that the acupuncture had probably harmed his back. He then consulted our hospital.
After admission, he continued to complain of back and left leg pain. Physical examination revealed a positive Lasegue sign (45°+) in the left lower limb. Neurological examination of both legs was normal, and urinary function was normal. There were no needle marks or signs of a skin infection in the lower back area. His medical history showed no other pathological conditions, and he had been taking no anticoagulant medicine recently. Laboratory ndings (routine blood tests, blood biochemistry evaluations, blood clotting function tests) were within the normal range. Because he had been treated at another hospital, the needle size and the depth of needle insertion were unknown.
His MRI results after admission showed an intraspinal mass at L5/S1. The mass, which was oval, showed T2 isointensity and T1 hyperintensity. On MRI, it resembled an intraspinal synovial cyst. We

Discussion And Conclusions
In the previously reported cases of intraspinal hematoma after acupuncture, the hematoma extended more than one level and had a fusiform shape. T1-weighted imaging in those cases revealed a low-signal mass. In the present case, the different type and T1-weighted signal hyperintensity may have been due to a relatively longer history-that is, our patient underwent MRI 1 month after his acupuncture, whereas patients in previous studies were evaluated only a few hours to a few days after their acupuncture. Thus, the hematoma in our patient might have formed an in ammatory capsule over time.
Unlike the mass in our patient, most intraspinal cysts have T1 hypointensity on MRI scans [4].
Nevertheless, both intraspinal hematomas and cysts display various MRI signals [4][5][6], making it di cult to distinguish these two diseases when the shape of the mass is cyst-like on MRI scans, as in our case. A careful medical history review to determine the basis of the pain (e.g., facet joint block, acupuncture, epidural injection) is helpful for pinpointing the correct diagnosis. Finally, the pathology of the intraspinal mass can be con rmed only by evaluating the intraoperative ndings.

Declarations
Ethics approval and consent to participate This patient provided informed consent that all his medical information and imaging data could be used for medical research.

Consent for publication
The study was approved by the ethics committee of the third a liated hospital of Guangzhou medical university.
Availability of data and materials Not applicable. thought the mass was probably a ligamentum avum cyst or a facet joint cyst because it was attached to the facet joint on the left side of the spinal canal (Fig. 1).
Thus, with the possible diagnosis of an intraspinal cyst compressing the right S1 nerve root, we performed a laminectomy to relieve the patient's low back pain, for which analgesic treatment was ineffective. Removal of the L5 left inferior margin plate clearly exposed the mass, which proved to be a blood clot surrounded by epidural fat with no capsule. It did not contain any jelly-like material, there was no calci cation around the rim, and the nerve root and dura mater were intact. Thus, an epidural hematoma was diagnosed. The surgery went smoothly and was completed in less than 1 h. His symptoms were immediately relieved by the surgery, and he showed good function at the nal follow-up visit in April 2020.