Subdural and epi-arachnoid hemorrhage following spinal epidural block requiring hematoma removal: illustrative case

Abstract

BACKGROUND

Spinal epidural block is widely used for pain control. While complications such as CSF leakage or epidural hematoma are occasionally reported, subdural hematoma (SDH) following an epidural block is rare. To the authors’ knowledge, a hematoma involving both the subdural and epi-arachnoid spaces has not been previously reported.

OBSERVATIONS

A 49-year-old man with a history of chronic back pain developed severe bilateral leg paresthesia 8 days after a routine lumbar epidural block. MRI revealed an SDH extending from T8 to S3, compressing the dorsal spinal canal. Surgical decompression was performed via hemilaminectomy at L2–3 and L5–S1, followed by durotomy and irrigation with a Nelaton catheter. The patient had full symptomatic relief postoperatively and showed complete hematoma resolution within 3 months.

LESSONS

Although spinal epidural block is generally considered a safe procedure, rare complications such as SDH can occur. Physicians should maintain a high index of suspicion for such complications in patients presenting without new neurological symptoms after epidural block. When diagnosed with SDH, surgical treatment including laminectomy and irrigation via Nelaton catheter may be necessary to optimize patient outcomes.

https://thejns.org/doi/10.3171/CASE25448

Epidural block is widely used for pain control during labor, surgery, and chronic pain management. While generally safe, it is not without risk. Major complications have been reported in approximately 1.36% of patients, including epidural hematoma (0.02%), postoperative neurological deficits (1.12%), postdural puncture headache (0.14%), and systemic local anesthetic toxicity (0.08%).¹ Subdural hematoma (SDH) following epidural block is rare but potentially serious, causing compression and nerve injury that can lead to permanent sequelae. Spine SDH may be caused by many factors, including difficulties during dural puncture, coagulation disorders, and increased intra-abdominal pressure.^2–6 Prompt diagnosis and intervention are critical to favorable outcomes. Therefore, this study aims to review the literature on epidural block–related SDH, discuss effective treatment strategies, and present the clinical course of a patient successfully treated surgically.

Illustrative Case

Clinical Presentation and Imaging

A 49-year-old male with a history of chronic back pain had been receiving spinal epidural blocks annually for several years. On September 30, 2024, he underwent a routine epidural block. Eight days later, he returned with severe back pain and paresthesia in both legs. He had no signs of CSF leakage such as dizziness or postural headache, and no motor weakness or anal sphincter tone reduction. MRI demonstrated an acute to subacute SDH extending from T8 to S3, predominantly on the dorsal aspect, causing moderate to severe central canal compromise from L1 to L5 (Fig. 1). Contrast-enhanced MRI was performed to rule out arteriovenous malformation (AVM), arteriovenous fistula (AVF), or tumor bleeding, but showed no abnormal enhancement (Fig. 2). The patient had no bleeding tendency, and he was not taking any antiplatelet or anticoagulant medications at the time of presentation.

FIG. 1.

After the epidural block, T2-weighted nonenhanced MRI revealed a subacute subdural spinal hematoma. A and B: Sagittal T2-weighted MR images showing a subacute SDH extending from T8 to S3, located in the dorsal aspect of the spinal canal. C–F:Axial T2-weighted MR images at the L2–3 (C), L3–4 (D), L4–5 (E), and L5–S1 (F) levels, demonstrating the SDH along the posterior aspect of the thecal sac, with the most prominent compression observed at the L4–5 and L5–S1 levels.

FIG. 2.

Contrast-enhanced MRI was performed to rule out AVM, AVF, or tumor bleeding, but showed no abnormal enhancement. A and B: Sagittal contrast-enhanced T1-weighted MR images. C–F:Axial contrast-enhanced T1-weighted MR images at the L2–3 (C), L3–4 (D), L4–5 (E), and L5–S1 (F) levels.

Surgery

The patient underwent surgery in the prone position under general anesthesia. Given the diagnosis of a subacute spinal hematoma extending from T8 to S3, we planned to perform a laminectomy, durotomy, and hematoma irrigation using a Nelaton catheter (Fig. 3).

FIG. 3.

The 6-Fr Nelaton catheter used during surgery.

One of the key considerations was determining the optimal level for the laminectomy, due to the hematoma’s extensive craniocaudal involvement. The L4–5 level, where the patient had previously received an epidural block, was avoided due to the potential risk of active bleeding. Additionally, the conus medullaris was located posterior to the L1 vertebral body, making upper-level approaches potentially hazardous.

Therefore, we selected L5–S1, where the hematoma burden was greatest, as the primary surgical level. In addition, to access the central portion of the hematoma, we performed a second laminectomy at the L2–3 level.

At both levels, we performed a hemilaminectomy to maximally expose the neural elements. After durotomy, we observed a massive subacute hematoma and proceeded with craniocaudal evacuation. A Nelaton catheter was inserted into the subdural, epi-arachnoid space, and extensive irrigation with normal saline was performed using a 50-ml syringe.

Interestingly, no CSF leakage was observed following durotomy. Instead, sunken arachnoid membrane and rootlets were seen beneath the hematoma. The arachnoid membrane remained intact without evidence of rupture. Additionally, no tumor or vascular malformation was identified intraoperatively, consistent with the findings from preoperative contrast-enhanced MRI.

Following thorough irrigation, the previously compressed neural elements began to reexpand. Hemostasis was achieved, and a Jackson-Pratt drain was placed prior to closure. Unfortunately, intraoperative photographs were not obtained.

Postoperative Course

Immediately following surgery, the patient reported a marked reduction in pain, with the intensity decreasing from a preoperative visual analog scale score of 10 to 1. No neurological deficits or CSF leakage were observed. On postoperative day 6, follow-up MRI demonstrated complete resolution of the hematoma at the surgical site (Fig. 4); however, residual hematoma was still noted in adjacent, nonoperated regions. By postoperative day 14, subsequent MRI revealed further reduction in the residual hematoma, although incomplete resolution persisted. The patient was discharged without significant pain and was able to resume normal daily activities without discomfort. At the 3-month follow-up, MRI demonstrated complete resolution of the hematoma (Fig. 5). During more than 1 year of follow-up, the patient remained free of sequelae, with no evidence of rebleeding or other significant complications.

FIG. 4.

T2-weighted MRI was performed 6 days after surgery. A and B: Postoperative sagittal MR images showing decreased hematoma. C–F: Axial MR images at the L2–3 to L5–S1 levels. Hematoma reduction is noted at L4–5 and L5–S1 with improved visualization of the thecal sac.

FIG. 5.

T2-weighted MRI was performed 3 months after surgery. A and B: Sagittal MR images showing complete resolution of the hematoma. C–F: Axial MR images at the L2–3 to L5–S1 levels, confirming complete hematoma resolution.

Informed Consent

The necessary informed consent was obtained in this study.

Discussion

Observations

The occurrence of subdural or epi-arachnoid hematoma following an epidural block is exceedingly rare. According to the literature, there have been reports of SDHs following epidural anesthesia;⁷ however, even these are limited to isolated case reports, underscoring their rarity.^2,8 Furthermore, hematomas following a simple epidural block are extremely uncommon, and cases involving the epi-arachnoid space, as in this report, are nearly unprecedented.

The subdural and epi-arachnoid spaces are considered virtual spaces anatomically; that is, they do not exist as real spaces under normal physiological conditions. Moreover, these regions are generally avascular, making the likelihood of hematoma formation extremely low. In contrast, epidural hematomas may occur due to injury to the epidural venous plexus, and subarachnoid hematomas are usually caused by damage to blood vessels within the subarachnoid space, such as spinal arteries or veins. Intracranial SDHs typically result from bridging vein rupture; however, such veins are absent in the spinal region, making spinal SDHs even less likely. Therefore, the presence of massive hematoma extending from T8 to S3, as seen in this case, is highly unusual.

Several hypotheses may explain the origin of this hematoma. First, during the epidural block, the needle may have inadvertently penetrated the arachnoid membrane, injuring subarachnoid vessels. This could have led to gradual bleeding into the epi-arachnoid space. Over time, the arachnoid membrane may have been resealed, preventing CSF leakage. This theory is the most plausible, especially considering that the patient’s symptoms progressed gradually over several days. Although bleeding from the epidural venous plexus with downward extension beneath the dura could also be considered, the absence of any epidural hematoma makes this explanation less likely. Second, direct injection into the subdural, epi-arachnoid space may have temporarily expanded these potential spaces. A ruptured vessel in the area could then have allowed progressive hematoma accumulation. This theory could also explain the intact state of the arachnoid membrane and the longitudinal spread of the hematoma. Third, bleeding due to vessel traction induced by CSF leakage might be considered; however, the patient showed no symptoms of CSF leakage, and intraoperative findings confirmed the absence of such leakage. Other potential causes, including drug-induced bleeding or vascular malformations, were also considered. However, the patient’s symptoms clearly began after the epidural block, and contrast-enhanced MRI showed no evidence of vascular anomalies, making these causes highly unlikely.

The choice of surgical methods and levels involved was also a key factor. For irrigation of massive hematoma, the use of a Nelaton catheter allowed effective evacuation with minimal laminectomy. In cases of chronic hematoma, durotomy could be limited to the minimum necessary to insert the catheter, and in subacute cases, skipping certain levels enabled further reduction of laminectomy levels. Based on clinical experience, the Nelaton catheter can be used to irrigate hematoma approximately one level above and below the surgical site. Due to its soft rubber material and small size, it can be inserted with minimal risk of direct neural injury.

One limitation in surgical planning was the decision not to perform laminectomy at the L4–5 level, which might have allowed direct identification of the bleeding source. Given the extensive hematoma from T8 to S3, determining the optimal surgical levels required significant deliberation. In retrospect, hematoma evacuation was successfully achieved through a minimal laminectomy.

In this case, the absence of CSF leakage meant that typical symptoms of dural puncture, such as postural headache or nausea, did not appear. Additionally, there was no neurological deficit, which contributed to the diagnostic challenge. When the patient returned on postinjection day 2 complaining of pain, it was initially interpreted as irritation from the block itself. Consequently, the medication dosage was increased and a stronger medication was prescribed; MRI was not performed. Only on day 8, when the patient returned with severe persistent pain, was an MRI conducted and the diagnosis confirmed. There have been previous reports of SDH following epidural block; however, in those cases, the presence of neurological deficits allowed for early diagnosis and timely treatment.^9,10 In contrast, as in the present case, diagnosis becomes more challenging in the absence of neurological symptoms. Fortunately, the patient showed good postoperative recovery without rebleeding or sequelae. However, delayed diagnosis or surgical intervention could have resulted in permanent disability. In fact, there are reports of patients developing permanent deficits even after surgical intervention for SDH following epidural anesthesia.¹¹

Lessons

This case highlights that severe spinal hematomas can present solely as pain without neurological deficits following epidural block. Furthermore, when such rare cases are encountered, the surgical approach described may minimize patient morbidity while achieving effective hematoma evacuation.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: all authors. Acquisition of data: Han. Analysis and interpretation of data: Han. Drafting the article: Han. Critically revising the article: Han. Reviewed submitted version of manuscript: Han. Approved the final version of the manuscript on behalf of all authors: Han. Statistical analysis: Han. Administrative/technical/material support: Han. Study supervision: all authors.

Correspondence

Sang Youp Han: Spine Center, The Leon Wiltse Memorial Hospital, Suwon, Korea. hsy850316@gmail.com.