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spinal cord hematomas are uncommon . among spinal cord hematomas , subdural hematoma ( sdh )
spinal sdh can be developed as a result of anticoagulation therapy , blood dyscrasia , spinal puncture , trauma , spinal anesthesia or vascular malformation1,7 ) .
spinal sdh is classified as acute , subacute , chronic according to the course of clinical symptoms8 ) .
the symptoms of acute spinal sdh begin with severe and sudden onset back pain accompanied by severe radicular pain , and rapid progression to paraplegia within several days .
the symptoms of subacute sdh begin with less well localized back , hip and leg pain , gradually progress to paraplegia over a period of 1 week .
spinal chronic sdh begins with the signs and symptoms of progressive spinal cord compression occurring over a period of several months to several years , with mild or absent pain .
spontaneous spinal sdh occurs most commonly in the lower thoracic or thoracolumbar lesions and develops during the sixth decade of life5,12 ) . for the best outcomes ,
we report a case of spontaneous spinal chronic sdh located at lumbosacral region without underlying pathology .
a 74-year - old male was presented with low back pain and both buttocks pain for 16 days .
the pain in both buttocks had gradually progressed to both legs in the l5 dermatome and the intensity of pain was aggravated during the last 3 days .
there were no history of trauma , infection or anticoagulant therapy . on admission , his vital signs were stable , and neurological examination revealed normal tone in upper limb and lower limb .
power in extremities were grade 5/5 at all joints in medical research council muscle strength grading scale2 ) .
the plane x - ray films of lumbar spine showed multiple spur formation and intervertebral space narrowing at l5-s1 and some degenerative change .
lumbar spine magnetic resonance image revealed a diffuse subdural infiltrating mass compress nerve roots at the level of l2-s2 .
the mass presented an isoto - hyperintense signal on t1-weighted magnetic resonance imaging ( mri ) to the spinal cord , and an iso - to - hypointense signal on t2-weighted mri ( fig .
1 ) . as the patient complained of unbearable pain , we underwent an emergency surgical decompression with l4 and l5 laminotomy .
there was no obvious extradural hematoma and abnormality but the dura mater was bluish in color and tense .
the hematoma was dark , red wine color and well liquefied , and was evacuated by suction . after normal saline irrigation and bleeding control , watertight dural closure was performed .
a follow - up mri study performed 2 months after operation , documented no evidence of residual hematoma ( fig .
- follow up , there was no postoperative complication and the patient had no more pain .
spinal sdh is remarkably uncommon , which must be diagnosed accurately and promptly . in some cases , compression of the spinal cord by spinal sdh
based on causes , idiopathic spinal sdh is rare and in secondary spinal sdh , the most common causes of spinal sdh are coagulopathies , anticoagulant therapy , spinal trauma , or post iatrogenic circumstance7,9,11 ) . other various causes include tumors , ruptured vascular malformation including arteriovenous malformation , or aneurysm of spinal artery5,9,11 ) . the mechanisms of formation of spinal sdh remain unclear .
various hypotheses of spinal sdh have been proposed , increased intravascular pressure in subdural space due to increased intrathoracic or intraabdominal pressure resulting from trauma , cause a failure in the spinal cord vascular .
another hypothesis is migration of hematoma from intracranial subarachnoid to the spine due to gravity8,13 ) .
mri provides signal from hematoma changes over time after onset that is similar to those of brain hematoma5,6 ) . immediately after attack
, hematoma appearance on t1-weighted image is intermediate signal intensity area and on t2-weighted image is low signal intensity . between 7 to 14 days after attack
, hematoma appears as high - to - intermediate signal intensity on t1-weighted image , and an increase in signal intensity on t2-weighted image . in our case ,
signal intensity was high - to - intermediate in t1-weighted image , and low - to - intermediate image in t2-weighted image .
the mri findings are not typical results of chronic spinal sdh which make preoperative diagnosis difficult . in the operation field ,
the treatment of choice is laminectomy and drainage of hematoma4,9,13 ) . despite of spontaneous remission of intraspinal
hematoma has been reported , early surgical decompression is commonly required , because of progression of neurological deterioration caused by spinal cord compression , ischemia , and direct injury to spinal cord .
spinal chronic sdh is rare but should be considered in patients with sudden back pain , radiating pain to the upper or lower extremities or trunk and motor , sensory , autonomic disturbance . in these patients ,
reports of spontaneous spinal chronic subdural hematoma ( sdh ) are extremely rare . in the limited cases 
 reported , the origin , symptoms and treatments are diversely revealed . therefore accurate diagnoses and proper treatments are difficult to determine . 
 we report a 74-year - old male presented with severe low back pain and both buttocks pain . 
 magnetic resonance imaging showed a diffuse subdural infiltrating mass compress nerve roots at the level of l2-s2 . 
 emergency operation for decompression and excision of mass revealed spinal chronic sdh . 
 his pain was subsided after the operation . 
 we report a rare case of idiopathic lumbosacral spinal chronic sdh and discuss various causes and treatments .