Massive Acute Spinal Subdural Hematoma Causing Sudden Onset Paraplegia in a Patient on Anticoagulation

Spinal subdural hematoma (SSDH) is a rare but known entity that can cause severe and irreversible motor, sensory, and autonomic dysfunction if not decompressed in a timely manner. We present here a 74-year-old female on anticoagulation who developed sudden onset back pain with rapidly progressive paraplegia. On neurologic exam, she was completely flaccid in the bilateral lower extremities with absent sensation from the umbilicus down. Imaging demonstrated a massive extra-axial spinal hematoma from T12 to S1 that initially was believed to be epidural in origin. She was taken emergently to the operating room for a T11-L5 decompressive laminectomy, and dural opening demonstrated a thick subdural clot encasing the conus and cauda equina confirming the subdural pathology. Despite decompression and partial evacuation of the subdural hematoma, she did not recover neurologic function.


Introduction
Spinal subdural hematoma (SSDH) is a rare but known entity that can cause severe and irreversible sensorimotor and autonomic dysfunction if not decompressed in a timely manner [1][2][3][4]. We report here a case of a massive thoracolumbar SSDH in the setting of therapeutic anticoagulation causing acute-onset paralysis.

Literature Search
A literature search was performed to determine if SSDHs of this size and severity of symptoms were reported elsewhere. We searched PubMed using the terms "spinal subdural hematoma," "massive spinal subdural hematoma," "acute spinal subdural hematoma," with the qualified "AND anticoagulation," "AND warfarin," "AND heparin," "AND aspirin," "AND apixaban," "AND rivaroxaban," "AND dabigatran," with article-type filters for case reports, clinical studies, clinical trials, comparative studies, observational studies, reviews, and systematic reviews. We also performed reviews of citations within articles we found. Our initial search yielded 1,066 articles. After filtering for atraumatic or nonprocedural SSDH, we found 202 articles. Those that did not reference an anticoagulant in the title or body of the article were excluded, leaving a total of 24 articles.

Case Report
We present here a 74-year-old female on anticoagulation who developed sudden onset back pain and rapidly progressive flaccid paraplegia. On neurologic exam, she was completely flaccid in the bilateral lower extremities with absent sensation from the umbilicus down. Magnetic resonance imaging (MRI) demonstrated a massive ventral spinal subdural hematoma from T12 to S1 (Figure 1). Due to these findings, she was taken emergently to the operating room for decompression and evacuation.

Operation
A T11-L5 laminectomy was performed for complete epidural decompression. Dural opening demonstrated a thick subdural clot encasing the conus and cauda equina ( Figure 2). A partial evacuation was performed focusing on the proximal hematoma at the spinal cord and conus; the rest of the clot distal at the cauda equina was partially removed with a combination of direct evacuation and irrigation due to the difficult consistency of the clot encasing the cauda equina roots.

Postoperative Course
Postoperatively, she did not have any recovery of strength or sensation. She was monitored as an inpatient for 3 days and subsequently discharged to an acute rehabilitation center. At six months follow-up, there has been no recovery of neurologic function.

Literature Review Results
Our review of the literature resulted in 202 articles discussing atraumatic and nonprocedural iatrogenic SSDH. They included case reports, reviews on management of SSDH, and reviews on imaging diagnosis of SSDH. We found 24 case reports on SSDH in patients who had been anticoagu-lated (Table 1). There was an even distribution of male and female patients (12 males and 12 females) found in this literature review, and the average age was 63.06 years with a range of 38 to 80 years old ( Table 2). The majority of patients in the series had atrial fibrillation as a comorbidity (15/24), with others including stroke (2/24), cardiovascular and disease (3/24), venous thromboembolism (2/24), cardiac valve replacement (2/24), and other (1/24). 2/24 were on low molecular weight heparin (LMWH), 4/24 were on aspirin (in combination therapies), 10/24 were on warfarin, 2/24 were on clopidogrel, 1/24 was on ticlodipine, 3/24 were on apixaban, 4/24 were on rivaroxaban, and 1/24 was on dabigatran. 13/24 patients had multilevel or diffuse SSDH, 9/24 were confined to the thoracic region and 1/24 to the lumbar region, and none had purely cervical or sacral SSDH. 19/24 had no associated subarachnoid hemorrhage (SAH), 4/24 had definite SAH, and 1/24 had indeterminate SAH. 5/24 patients did not improve, 13/24 partially improved, 5/24 fully recovered, and 1 patient died of a cardiac arrest. 16/24 patients received operative intervention, and 8/24 received conservative treatment (including the patient that died). Of the patients that did not improve, all 5 underwent surgical intervention. 10/13 in the partial improvement had surgery compared to 3/13 who were managed conservatively. 4/5 patients who fully recovered were managed conservatively, and 1/5 was operated on.

Discussion
We present the case of a massive spinal subdural hematoma in an elderly female on anticoagulation causing severe back pain and rapid-onset paraplegia. SSDH as an entity has been previously described, including in association with anticoagulation. We report here a unique case of a massive thoracolumbar SSDH that initially was believed on radiological review to be a ventral epidural hematoma in origin.
Spontaneous spinal subdural hematoma (sSSDH) is a rare cause of back pain, paraplegia, and cauda equina syndrome and should be considered in a patient who is on anticoagulation, and no other precipitating events are identified [3]. The average age of patients in this case series was 63.06 years (note-one study simply reported the age as "middle aged"), which is similar to a recent study by Pereira et al. but differs from other older studies [3,4]. We found an even distribution of males (50%) and females (50%) in this case series, which is similar to previously reported rates [1,4]. The majority of patients in this series were on warfarin [5][6][7][8][9][10][11][12][13][14], which could be due to a higher rate or longer duration of warfarin use compared to newer novel oral anticoagulants (NOACs) and not necessarily due to the agent itself, though studies have shown lower rates of (unspecified) major bleeding events with NOACs [15][16][17][18][19][20][21][22][23]. We identified fewer patients on other agents (including antiplatelet therapies) that developed SSDH [14,[24][25][26][27][28].
SSDHs are often associated with coagulopathies (iatrogenic or related to impaired innate hemostasis mechanisms) and procedural iatrogenic causes, though there is still a significant amount of SSDHs secondary to arteriovenous malformations, trauma, and idiopathic causes [3,4,6]. The pathophysiology  Case Reports in Surgery of spontaneous SSDH is still unclear but is theorized to be caused by bleeding within the subdural space itself or as an extension of a subarachnoid bleed into the subdural space after an increase in intrathoracic or intra-abdominal pressure [1,3]. Indeed, there have been cases of concomitant SAH and SSDH [7,9,14,18,21]. Important prognostic factors include neurologic status at presentation, presence of coagulopathy, performance of lumbar puncture, and associated diseases [4]. Interestingly, extension of hematoma, surgery, and presence of SAH were not found to be significant predictors of outcome.   Case Reports in Surgery   6 Case Reports in Surgery MRI is considered the gold standard in the diagnosis of SSDH, but digital subtraction angiography may be useful if spinal AVM is suspected [2]. SSDH can be managed conservatively with medical management (often including steroids), percutaneous drainage, and surgical evacuation [3,29]. Though the literature suggests that conservative management results in better outcomes, this may be related to bias in choosing patients with less severe symptoms for medical management whereas more impaired patients are selected for surgical intervention [4].

Conclusion
SSDH is a rare but serious cause of rapid-onset back pain, sensorimotor, and autonomic deficits, and in some cases, mortality. It is often associated with iatrogenic causes including anticoagulation (as in this case) but in some instances may be idiopathic. MRI is the gold standard for diagnosis. Patients with mild or moderate symptoms can be managed conservatively, but urgent surgical decompression and clot evacuation are warranted in patients with severe symptoms to prevent permanent neurologic injury or death.

Data Availability
The imaging and photographic data used to support the findings of this study are included within the article.