a 56 year old man presented with progressive left lower limb radiculopathy and paraesthesias with claudication of three days duration . mri revealed a subdural space occupying lesion compressing the cauda equina at l5-s1 level producing a  y shaped dural sac ( y sign ) , which was hyperintense on t1w imaging and hypointense to cord on t2w image . the knowledge of mri appearance with respect to the chronological stage of the bleed is essential to avoid diagnostic and hence surgical dilemma m r i has made it possible to chronologically label these haematomas as hyperacute , acute , subacute and chronic . a 56 year old gentleman presented to emergency with progressive history of pain along the left posterior aspect of thigh and postero lateral aspect of leg , going up to the lateral aspect of foot since three days . his pain worsened after walking for a couple of minutes and was relieved after taking rest . the general examination was unremarkable . on local examination there was no spasm or tenderness at the lumbar spine . mri was done , which revealed a subdural space occupying lesion compressing the cauda equina at l5-s1 level producing the  y  shaped dural sac on axial images ( fig 1 ) . the lesion was hyperintense on t1w imaging ( fig 2 ) and hypointense to cord on t2w image ( fig 3 ) . the patient did not give any history of spinal intervention or bleeding diathesis or medications . the patient underwent decompressive durotomy and frozen section biopsy which confirmed the diagnosis of a hematoma . t1w axial image at the l5 mid body level showing the ' y'shaped sign as well as the compression of the neural structures .. t1w midsagittal image shows at l5-s1 , iso to hyperintense signal with respect to the cord signal . note the pooling of the bleed on the dorsal aspect of the the cal sac than ventrally . also note the compression of the neural structures t2w mid sagittal image showing iso intensity of the lesion as compared to the cord signal . sagittal s t i r sequence showing iso to mild hyperintense signal with respect to the spinal cord . spontaneous non traumatic spinal subdural hematomas ( ssh ) are rare and literature is sparse . in contrast to their cranial counterparts which have bridging veins as a source of bleed , the pathogenesis and aetiology of ssh are not fully known . various theories have been studied like migration from the intracranial space ,   redistribution of clival subdural hematoma to dependant areas in lower lumbar spine   and collection of blood in the  intradural  space . . these have been reported to occur after vigorous back massage   and even paraspinal muscle needling . symptoms include back pain and/or radiculopathy with variable amount of neurological deficit ranging from an acute rapidly progressive paraparesis to slowly developing mild deficit depending on the severity of neural compression . about half of these patients develop complete sensorimotor deficit .   symptoms also vary according to the level of the bleed . the extent of bleed can vary from one to seven segments   mri is the investigation of choice for diagnosis as well as for planning surgery . the differential diagnosis of an intradural mass includes haematoma , lipomatosis , abscess and tumours . in our case the mri findings in a spinal bleed vary according to the stage of bleed .   the hyperacute bleed is iso / hypointense on t1w sequence and hyperintense on t2w sequence . the acute hematoma is slightly hypo-/isointense on t1w images and hypointense on t2w images . in early subacute hematoma our patient had an early subacute haematoma as it was hyper on t1w and hypo on t2w images . yshaped sign we noted , is similar to the  inverted mercedes benz  sign described by kasliwal et al . . this sign is a result of the encasement of blood around arachnoid lined neural structure . similarly , in the sagittal sections , the bleed takes the contour of the compressed arachniod membrane resembling two convex discs in apposition to each other , suggestive of liquid nature of the lesion . location of the lesion in the dependant area ( l5-s1 ) adds to this information . in contrast , intradural lymphomas usually take a fusiform or sausage shape , although any shape is possible . treatment involves conservative management with serial mri in cases with preserved neurology , . in cases with serious neurological deficit , laminectomy and drainage thus , one needs to be aware of the different stages of bleed and its mri appearance for diagnosis . early diagnosis using mri imaging and prompt management is the key to prevent disastrous neurological consequences . the knowledge of mri appearance with respect to the chronological stage of the bleed is essential to avoid diagnostic and hence surgical dilemma . spinal subdural hematoma should be a differential in cases presenting with rapidly progressive radiculopathymri is the investigation of choicea detailed knowledge of the mri appearance as per the chronological stages helps in diagnosis and management planning . spinal subdural hematoma should be a differential in cases presenting with rapidly progressive radiculopathy mri is the investigation of choice a detailed knowledge of the mri appearance as per the chronological stages helps in diagnosis and management planning .
introduction : spinal subdural hematoma is a rare cause of radiculopathy and spinal cord compression syndromes . 
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 early diagnosis is essential . chronological appearance of these bleeds vary on mri.case report : a 56 year old man presented with progressive left lower limb radiculopathy and paraesthesias with claudication of three days duration . 
 mri revealed a subdural space occupying lesion compressing the cauda equina at l5-s1 level producing a  y shaped dural sac ( y sign ) , which was hyperintense on t1w imaging and hypointense to cord on t2w image . 
 the stir sequence showed hyperintensity to cord . 
 there was no history of bleeding diathesis . 
 the patient underwent decompressive durotomy and biopsy which confirmed the diagnosis.conclusion:spinal subdural hematoma may present with rapidly progressive neurological symptoms . 
 mri is the investigation of choice . 
 the knowledge of mri appearance with respect to the chronological stage of the bleed is essential to avoid diagnostic and hence surgical dilemma