Spinal subdural hematoma in a patient with immune thrombocytopenic purpura following microvascular decompression: a rare case report

Introduction

Microvascular decompression (MVD) is a type of craniotomy that can effectively treat cranial nerve disorders, including trigeminal neuralgia (TN) and hemifacial spasm (HFS). Spinal complications are rare with this procedure. ¹ The most common complication is headache, which is usually self-limiting. Serious complications include extra-cranial nerve damage, cerebral infarction, intracranial hemorrhage, and central nervous system infection. Spinal subdural hematoma (SSDH) after brain surgery is a rare and serious entity that can cause permanent neurological deficits. ² Only a few cases have been reported, mostly because of changes in intracranial pressure caused by cerebrospinal fluid (CSF) release. ³ Patients with immune thrombocytopenic purpura (ITP) are prone to intraspinal hematomas because of decreased platelet counts and prolonged bleeding time after brain surgery. We report a case of SSDH without timely correction of thrombocytopenia after MVD but with neurological recovery after conservative treatment. The pathogenesis of SSDH after MVD includes the downward movement of blood from the cranial compartment by gravity, excessive decompression of the intracranial space during surgery, and decreased CSF pressure caused by drainage. The effects are associated with body position or the release of CSF too rapidly or in a large volume. SSDH is commonly associated with trauma, blood disorders, anticoagulation, lumbar puncture, and vascular malformations. There are only a few case reports of SSDH after MVD surgery. The case presented here helps fill this gap.

Case report

A man in his early 50 s presented to our clinic complaining of coexisting HFS and TN and an 8-year history of ITP. The reporting of this study conforms to the CARE guidelines (for case reports). ⁴ The patient signed an informed consent form for treatment and to publish this case. The patient had several episodes of epistaxis, and his platelet count remained between 30 × 10⁹/L and 50 × 10⁹/L (normal range, 100.0–300.0 × 10⁹/L), with a minimum level of 2 × 10⁹/L. The patient repeatedly received methylprednisolone, prednisone, and platelet transfusion. His platelet count before surgery was 107.0 × 10⁹/L with normal coagulation parameters. HFS and TN were treated using a left suboccipital retrosigmoid approach under general anesthesia, and the procedure lasted 180 minutes. No spinal canal trauma occurred, and no obvious bleeding was observed during the perioperative period. On the first postoperative day, the platelet count was 70.0 × 10⁹/L. However, on the second postoperative day, laboratory tests showed a significantly decreased platelet count of 30.0 × 10⁹/L, activated partial prothrombin time of 22.7 s (normal, 23.0–38.0 s), and prothrombin time of 12.4 s (normal, 10.0–14.0 s). The patient complained of acute low back pain and sciatica. No numbness or bowel or bladder dysfunction was observed. Magnetic resonance imaging (MRI) of the lumbar spine showed a subdural hematoma extending from L3 to L4 with compression of the cauda equina (Figure 1). The lesions appeared isointense on T1-weighted images and hypointense on T2-weighted images, which met the criteria for acute SSDH. ⁵ MRI revealed no vascular malformations. Because the patient showed no neurological symptoms other than low back pain and sciatica, conservative treatment, fresh platelet transfusion, and intravenous methylprednisolone were given. The platelet count increased to 138.0 × 10⁹/L, and the pain gradually subsided after 2 weeks. During the 1-year follow-up, the patient was in good condition and had no neurological deficit.

OPEN IN VIEWER

Figure 1.

Magnetic resonance imaging (MRI) findings of the lumbar spine. Sagittal T1 (a) and T2 (b) MRI of the lumbar spine showed a subdural hematoma extending from L3 to L4. The hematoma was isointense on T1-weighted images and hypointense on T2-weighted images (white arrows). Axial T2 MRI (c) revealed that the hematoma was compressing the cauda equina (white arrow).

Discussion

During MVD surgery, a small amount of CSF should be slowly released to expose the intracranial subarachnoid space to simplify the operation. Many common complications can occur during surgery, such as headache caused by CSF secretion; intracranial hypotension, vasospasm, rupture, and bleeding; cerebral infarction or cerebral hemorrhage caused by traction; hearing loss; and additional damage to cranial nerves. Postoperative SSDH can lead to catastrophic complications such as spinal cord injury, neurological deficits, acute low back pain, and sciatica, ⁶ as observed in our patient. Although the exact mechanism of SSDH is unclear, intracranial surgery in patients with ITP increases the risk of developing SSDH. ⁷ In this case, the presence of a spinal cord hematoma and a sudden onset of neurological dysfunction suggested intracranial hypotension caused by brain surgery and vascular damage caused by chronic ITP that was not corrected in a timely manner. ⁸ We speculate that a small amount of CSF was released during MVD surgery, leading to intracranial hypotension, and transmission into the spinal subdural space may have led to spinal vascular rupture if postoperative rehydration was insufficient. Although subdural hemorrhage is common, it is usually rare in patients with normal platelet production and function because of self-healing and drainage through the subdural space, and the incidence of symptom development is low. ⁹ However, in people with ITP, when blood vessels in the spinal cord rupture, because of the reduced number of platelets, clotting cannot be sufficiently performed. According to the above hypothesis, the patient developed SSDH on the second postoperative day and presented with low back pain.

According to previous reports, the pathogenesis of SSDH may be related to intracranial surgery, and various hypotheses have been proposed. ¹⁰ First, some authors have speculated that surgery-related CSF release causes intracranial hypotension, and transmission to the spinal subdural space may cause rupture of the spine vasculature. ¹¹ Marx et al ¹² reported an SSDH after translabyrinthine resection of a vestibular schwannoma, and they speculated that because of the decreased CSF volume during and after surgery, the bridging veins may have been torn, leading to SSDH. Second, some authors have hypothesized that intracranial subdural hematomas travel down the spinal cord through the spinal subdural space and accumulate in the most dependent sites of the spine.^13–15 In the present patient, intraoperative CSF release may have contributed to SSDH.

We selected suitable papers for review, including cases of lumbosacral subdural hematoma associated with craniocerebral surgery. Craniocerebral surgery involves creating a burr hole and performing ventriculoperitoneal shunting, craniotomy for cerebral aneurysm, temporal lobectomy, and brain tumor resection. SSDH is commonly associated with trauma, blood disorders, anticoagulation, lumbar puncture, and vascular malformations. There are only a few case reports of SSDH after MVD surgery. This study presents our case and fills this gap. The results of cases were favorable regardless of treatment, but one patient developed complete paraplegia because of a mass effect in the chest because of extensive subdural hematoma from the neck to the conus medullaris following resection of a posterior fossa tumor.

ITP is defined as an isolated low platelet count (low platelet count, normal blood and blood smear) because of the production of antiplatelet autoantibodies. It is characterized by low platelet counts and a variable bleeding tendency, occurring in 100 per 1 million people each year. ¹⁶ Most ITP patients have only mild bleeding symptoms, such as epistaxis, petechiae, or bruises. Severe bleeding events, such as intracranial hemorrhage, gastrointestinal bleeding, hematuria, hemoptysis, and persistent epistaxis, are rare. Therefore, ITP is now generally considered a benign disease. ¹⁷ ITP is a common cause of thrombocytopenia and bleeding complications, which could increase the bleeding tendency, and intracranial hemorrhage caused by ITP is the principal cause of death in ITP patients. The risk of hemorrhage depends on the severity of thrombocytopenia. In theory, ITP can cause intracranial hemorrhage including subdural hematoma, which can also lead to SSDH. According to the literature, the source of hemorrhage may be the more vascularized subarachnoid space. ¹² Morandi et al. ¹⁸ reported that SSDH might be caused by rupture of small vessels on the inner surface of the dura. In 2009, Yoo et al. ¹⁹ reported a case of paraplegia in a patient caused by spinal epidural hematoma because of bleeding caused by ITP. However, SSDH is rare in patients with ITP and has not been reported in the English literature to date. ²⁰

SSDH is usually associated with iatrogenic injury, spinal trauma, hematologic disorders, or anticoagulant therapy.^21–27 The clinical presentation of SSDH varies with the severity, speed, and level of spinal cord or nerve root compression. ²⁸ The symptoms of SSDH include acute compression of the spinal cord or nerve roots, resulting in symptoms such as acute back pain, pain radiating along the nerves, and acute motor or sensory disturbances, as well as autonomic dysfunction, such as urinary or fecal incontinence. However, not all patients with SSDH experience the above symptoms. For example, our patient had only acute low back pain and sciatica without motor or sensory disturbances. Because spinal cord compression carries serious neurological risks, spinal MRI is recommended to confirm the diagnosis when a patient complains of spinal symptoms.

Because SSDH caused by ITP is rare, definitive guidelines addressing this issue are lacking. George et al. ²⁹ reported that when ITP leads to neurological symptoms, internal bleeding, or emergency surgery indications, immediate intervention is required. The treatment goals of ITP-induced SSDH are to increase the platelet count, prevent further hemorrhage, relieve symptoms, and reduce spinal cord injury. High-dose parenteral corticosteroids and intravenous immune globulin are the first-line treatments, ³⁰ and platelet transfusion can transiently stabilize the platelet count and slow bleeding. The current patient received intravenous methylprednisolone and platelet transfusion, and the platelet count increased from 30.0 × 10⁹/L to 138.0 × 10⁹/L.

In general, acute SSDH is a potentially hazardous condition with possibly catastrophic consequences. Therefore, when the neurological status deteriorates (such as acute motor or sensory impairment or incontinence), emergency treatment, especially early decompression laminectomy and hematoma evacuation, is recommended. ³¹ Conservative treatment is also a choice for SSDH, but only for patients with mild neurological deficits or early spontaneous recovery or those who cannot tolerate surgery. ²² Several previous case reports of SSDH described spontaneous resolution after conservative treatment.^10,32,33 However, during the conservative treatment, attention should be focused on changes in the patient’s neurological function. If a progressive neurological deficit occurs, laminectomy and hematoma removal should be performed in a timely manner. In our case, the hematoma spontaneously resolved and the symptoms were improved by conservative treatment within 2 weeks, and no permanent neurological deficit occurred.

MRI alone may not definitively identify an SSDH. In the absence of any features suggestive of a spinal vascular lesion on MRI, spinal angiography is the best method to identify vascular malformations. We suggest routine spinal angiography. Because of the invasive nature of this procedure and because this study is contraindicated in patients with coagulopathies, the role of myelography in identifying spinal hematomas gradually diminished with the advent of computed tomography (CT) and then MRI. When MRI is interpreted in the absence of corresponding CT results or without a relevant clinical history, when the hematoma appears heterogeneous with variable signal intensity (depending on its exact age), and when blood is present in other compartments (such as the epidural, subarachnoid, or intramedullary space), MR images are less clear. The ability of MRI to discriminate subdural hematomas from hematomas in the subarachnoid space also remains to be determined. Nevertheless, despite these difficulties, we found that when plain CT and plain MRI were used together, a diagnosis of a subdural hematoma could be established.

Holocordic SSDH is an extremely rare disease, and the correct treatment has not been well standardized. Complete evacuation is not likely, and the surgical approach must be based on the patient’s neurologic and radiographic findings. MRI is the imaging modality of choice and should be performed without delay to confirm the diagnosis and to allow a prompt decision on the best type of treatment. Emergent surgical evacuation of the hematoma is often the only therapeutic option and is crucial in terms of prognosis, especially in the most severe and well-located cases. ³⁴

Conclusion

Brain surgery to release part of the CSF is a common surgical procedure. SSDH is a rare but potentially catastrophic complication, and brain surgery in patients with ITP increases the risk of SSDH. When chronic ITP patients have TN and HFS, MVD is a clear treatment strategy, as shown in this case. However, we stress the importance of minimizing the amount of CSF during surgery and providing timely and large amounts of intravenous fluids, monitoring platelet levels throughout the procedure, and maintaining them within the normal range. In addition, patients should be made aware of early signs of cord compression, such as severe low back pain or sciatica, so that complications can be assessed and treated more quickly if they do occur.

Supplemental Material