spontaneous spinal epidural hematoma ( sseh ) is an uncommon condition with an uncertain etiology that results in permanent neurological deficit or death when not treated appropriately . it is characterized by the initial manifestation of sudden - onset acute back or neck pain around the affected vertebra followed by the rapid progression of neurological dysfunction , which is caused by compression of the thecal sac and cauda equina . many cases can be diagnosed upon detailed neurological examination and magnetic resonance imaging ( mri ) . despite this , the etiology of ssee remains elusive in many cases , with no definitive inciting event . numerous risk factors have been reported including anticoagulant therapy , aspirin , coronary thrombolysis , lumbar puncture , hypertension , and ankylosing spondylitis . most surgeons advocate aggressive and prompt surgical intervention for sseh cases , interventions which may cause thecal sac and cauda equina compression and neurological dysfunction . here we reported a case of sseh partial recovery from neurological dysfunction after minimal invasive laminectomy through tubular retractors . in our department , we have generally used this approach to treat disc herniation , intraspinal tumors , and spinal stenosis . this procedure is similar to partial laminectomy with the exception of using a tubular retractor instead of an open approach ( fig . an 81-year - old woman was admitted to the neurology department experiencing persistent mild frequent urination and dysuria for 1 year without any reported inducing factors . the symptoms developed included numbness and weakness of the bilateral lower limbs and difficulty walking ( more severe in the right lower extremity ) 4 days before admission . progressive weakness developed over the next 3 days accompanied with pain in the lower limbs and lower back . upon neurological examination , weakness was noted in the right lower and left lower extremities at grades of 0/5(r ) and 3/5(l ) , respectively , according to the medical research council grading scale . the bilateral lower - limb exhibited normal muscle tension though deep - tendon reflexes appeared absent and babinski sign was negative . the remainder of the physical examination was normal . during sensory examination , this patient was not cooperative . the patient 's medical history did not reveal any notable events . at the moment of admission , the patient 's blood pressure was 158/78  mmhg and initial laboratory tests ( including complete blood count , chemistry panel , erythrocyte sedimentation rate , c - reactive protein , and coagulation evaluation ) revealed no remarkable contributions . after initial consultation , this patient was admitted to our department . the day after admission , mri of the thoracolumbar spine demonstrated an epidural hematoma extending from t-12 to l-5 with thecal sac and cauda equina displacement anterior ( fig . 2 ) . neurological deficits did not show any improvement during the course of the following 3 days . we next explained the condition of the disease and the operative method to the patient and her family . she was taken to the operating room for an emergency surgical decompression after the patient provided informed consent . after general anesthesia , the patient was placed in prone position . on the left side of the skin which is distant from midline 2  cm in t12 , l3 level and right side of the skin which is distant from midline 2  cm in l2 , l5 level , we made 4 longitudinal incisions about 2  cm length ( fig . separation of subcutaneous tissue reaching the muscle fascia and the paraspinal muscle was bluntly separated to lamina from the space of the multifidus and longissimus . a tubular retractor device was inserted in this space and the appropriate position was ascertained under x - ray . high - speed burr was used to grind off the lower edge of the t12 , l2 , l3 , and l4 lamina and the upper edges of the l1 , l2 , and l5 lamina ( fig . 3c ) , preventing damage to the zygapophysial joints and then dissected the ligamenta flava . the intraspinal dark red hematoma compressing the thecal sac and cauda equina were visible ( fig . the hematoma in the vertebral canal , which is adjacent to the tube , could then also be eliminated via adjustment of the angle of the tube . after evacuation all the hematoma , hydrogen peroxide and povidone  iodine was used to wash the operative cavity until we could clearly observe the dural thecal sac expansion and cerebrospinal fluid pulsation ( fig . the duration of the operation was about 3  h and the total blood loss was about 50  ml . a , sagittal t1-weighted mri revealed a hematoma ( isointense and slight hyperintense ) located posterior to the thecal sac and cauda equine , extending from t12 to l5 ( white arrows at the extremities of the mass ) . b , sagittal t2-weighted mri revealed a hematoma ( isointense and hypointense , white arrows at the extremities of the mass ) . c , axial t2-weighted mri showed the hematoma ( hypointense , white arrow ) compressed the thecal sac and cauda equina ( black arrow ) . a , dark red hematoma ( white arrow ) compressed the thecal sac . c , the upper and lower edges of l2 vertebral plate were ground off ( white arrows ) ; zygapophysial joints were integrated . d , after surgery , drainage catheters ( white arrows ) were positioned in the intraspinal extradural . e , each surgical incision was about 2  cm length ( 1 month postoperative ) . in the first 24 postoperative hours , there was no significant improvement in neurologic function . the lower back and bilateral lower limb pain was reportedly relieved on the third postoperative day ; moreover , there was an obvious improvement in the tendon reflexes of bilateral lower limbs as blunt tendon reflexes were observed . on the tenth postoperative day , the patient returned to normal urination and the catheter was removed . the left lower extremity showed improvement during postoperative recovery and muscle strength examination was normal by the tenth day after surgery . the condition of the right lower extremity was not apparently improved as muscle force examination received a grade of 1/5 until the patient was discharged . by the 3-month follow - up examination , however , the patient could walk slowly with the help of a cane and myodynamia testing of right lower limb received a grade of 4/5 . he supposed the mechanism that reversal of blood flow in the valveless epidural venous plexus caused by activities such as evacuation , sneezing , bending , coughing , and coitus could result in rupture of a fragile vein . those activities could lead to the change of intrathoracic and intra - abdominal pressure . beside this , traction on nerve roots during operations lead to disruption of the tortuous arterial plexus was suggested to be another source of epidural hematoma . taking into consideration that the pressure in the epidural veins is less than intrathecal pressure ( confirmed by the common observation that the normally expanded dural sac may tamponade epidural venous bleeding encountered during surgical procedures ) , beatty and winston hypothesized that arterial source bleeding is the main cause of acute sseh . however , groen has proposed that the majority of sseh actually results from a rupture of the posterior internal vertebral venous plexus , in a review of 199 cases of sseh . he has also considered that the rupture of the epidural artery might be responsible for some cases of sseh . the anatomical structure of human vertebra canal usually restricts epidural hematomas to the dorsal aspect of the epidural space with possible extension to the lateral gutters . in these cases , epidural hematoma is presented in the dorsal aspect , where the definitive cause of sseh can not be defined . various factors had been reported in the etiology of sseh , such as anticoagulant therapy , aspirin , coronary thrombolysis , lumbar puncture , hypertension , ankylosing spondylitis , and vascular malformation . patient age also appears to highly affect the level distribution of sseh as people who are less than 40 years old commonly experience sseh localized to the cervicothoracic region , whereas patients over 40 years old usually experience sseh in the cervicothoracic and thoracolumbar regions . our patient , who is 81 years old , presented a hematoma in the t12l5 , in accordance with the literature . the typical symptoms of sseh include a sudden onset of neck or back pain at the involved vertebral level with radiating pain , followed by rapid and progressive signs and symptoms of thecal sac and cauda equina compression . mri , myelography and computed tomography ( ct ) are commonly used to diagnose spinal epidural hematomas ; however , ct can not be used to determine when bleeding occurred and as such presents a limitation in terms of differential diagnosis . on the contrary , mri affords a superior diagnostic capability and has replaced ct and myelography as the main diagnostic tool . mri can inform the precise position of the hematoma , the extent and time frame of the bleeding , detection of thecal sac and cauda equina compression , and spinal cord edema . the patient presented here received mri examination on the sixth day after the initial presentation of symptoms . in this case , we could see an obvious long - segmented sseh had compressed and displaced thecal sac and cauda equina extending from the t12 to l5 ( sagittal view by t2-weighted mri ) . this sseh demonstrated isointensity and slight hyperintensity by t1-weighted mri and isointensity and hypointensity by t2-weighted mri ; this is in accordance with the subacute manifestation of hematoma in mri . in axial t2-weighted mri , we could clearly observe thecal sac and cauda equina compression and pushing to the left side of spinal canal . preoperative neurological status and the time interval to surgery appear to be 2 critical factors influencing the prognosis of sseh . a longer interval to surgery is detrimental to a positive neurological outcome , on the other hand , foo et al . shin et al speculated that early decompression ( > 12  hours constraining the ischemic change ) yields a more favorable recovery . they have also suggested that patients who experience early incomplete motor and sensory loss have a better chance at neurological recovery . liao et al also reported that patients with preoperative incomplete neurological deficits had a better neurological recovery than patients with preoperative complete neurological deficits . furthermore , prompt surgery ( less than 48  hours from the initial onset of symptoms and less than 12  hours of complete neurological deficits ) could also achieve a satisfactory neurological recovery in patients with preoperative complete neurological deficits . in our treatment , the patient was not diagnosed for the first time in our hospital though was admitted to our neurology department for conservative treatment . patient underwent surgery more than 6 days from the onset of symptoms and complete motor neurological deficit was observed in this patient . the mainstream treatment of sseh is emergency decompression and evacuation of the hematoma for prevention of permanent neurological deficits . some authors have suggested that in patients who demonstrate continual signs of clinical improvement and stability , conservative treatment may be adopted . iida y reported that resection of the whole lamina , spinous process , medial part of the facet joint , and flavum ligament seems to play an important role in the occurrence or progress of instability . the author also suggested that in the presence of adequate indications , partial laminectomy should be selected to avoid the occurrence or progress of instability at the operated level . muscular atrophy is another complication of open laminectomy which may occur due to the damage of the paraspinal muscles . in addition , asymmetry of the paraspinal muscle may also influence the occurrence of postoperative instability , preservation of paraspinal muscle and decrease the incidence of muscular injury have also reported that minimally invasive laminectomy has a lower rate of postoperative instability , reduced blood loss , and a shorter hospital stay than the conventional open laminectomy method . in this case report , a minimally invasive surgery was performed to decompress and evacuate hematoma via paraspinal approach through tubular retractors . through this alternative method , we are able to grind a hole on the skipped lamina with no damage to the zygapophysis . moreover , through this approach , a smaller trauma of the paraspinal muscles was achieved owing to the tubular retractor system . smaller intraoperative blood loss and shorter duration of postoperative pain are the other 2 advantages compared with standard laminectomy . in this case study , the intraoperative blood loss was about 50  ml and the patient did not feel obvious wound pain 3 days after surgery . additionally , postoperative mri showed complete removal of the sseh , the thecal sac and spinal cord expansion and recovery ( figs . we report that through this surgical approach , surgery channels were small and the zygapophysis maintained integrity in postoperative ct scan and reconstructed 3-dimensional ct scan ( fig . spinal instability was found and the walking capability of the patient was observed to be gradually improving . mri of the patient 9 days postoperative [ ( a ) sagittal t1-weighted , ( b ) sagittal t2-weighted , and ( c ) axial t2-weighted ) complete removal of the epidural hematoma , the thecal sac ( white arrows ) and spinal cord ( black arrows ) expansion and recovery . ct scan ( a ) and reconstructed 3-dimensional ct scan ( b and c ) of this patient 9 days postoperative . the surgical channel of operation ( white arrow and circle ) and the zygapophysis joint integrity ( black circle ) . the minimally invasive surgery used to decompress the spinal canal and evacuate the hematoma via paraspinal approach through tubular retractors may be an effective alternative method to treat sseh . this method has the advantages of causing minimal damage to the spinal bony structure , only a minor trauma to the paraspinal muscles , and a relatively short postoperative pain recovery time . we would like to thank clarity manuscript consultant llc ( indianapolis ) for their language - editing service .
abstractto report a minimally invasive paraspinal approach in the treatment of a case of spontaneous spinal epidural hematoma ( sseh ) . 
 we additionally aim to review the relevant literature to enhance our knowledge of this disease . 
 sseh is an uncommon but potentially catastrophic disease . 
 currently , most appropriate management is emergence decompression laminectomy and hematoma evacuation . 
 an 81-year - old woman was admitted to the neurology department with a chief complaint of bilateral numbness and weakness of the lower limbs and difficulty walking for 4 days with progressive weakness developed over the following 3 days accompanied with pain in the lower limbs and lower back . 
 no history of trauma was reported . 
 magnetic resonance imaging of the thoracolumbar spine demonstrated an epidural hematoma extending from t-12 to l-5 with thecal sac and cauda equina displacement anterior . 
 the patient was treated in our department with a minimally invasive approach . 
 this operation method had been approved by chinese independent ethics committee . 
 three months following the operation , the patient had regained the ability to walk with the aid of a cane and myodynamia tests revealed normal results for the left lower limb and a 4/5 grade for the right limb . importantly , no complications were exhibited from the surgical operation . 
 the minimally invasive paraspinal approach through tubular retractors is demonstrated here as an effective alternative method for the treatment of sseh .