many of patients are associated with underlying coagulopathy or receiving anticoagulant and antiplatelet agent11 ) . typical symptoms related with sdh are neck pain , radicular pain and myelopathy such as quadriplegia or quadriparesis3,4,7,9,11,12,13,14,15 ) . it is known to be a neurosurgical emergency but some cases with spontaneous remission have also been reported4,11,14,15 ) . and , ssdh may initially lead to misdiagnosis if the patient shows unusual manifestations11 ) . here in , we report a case of ssdh with sudden onset headache with no other neurologic symptoms . the patient was initially misdiagnosed as non - aneurysmal subarachnoid hemorrhage . a 66-year - old woman visited the emergency department with a sudden onset of severe headache . she had no underlying disease , no history of anticoagulant therapy , no hematological coagulopathy and no history of trauma . she only underwent a mastoidotomy due to chronic otitis media at our institute one week before admission . she was alert but had a severe , worsening headache of sudden onset and neck stiffness . no neurologic abnormalities were found in the cranial nerves and cerebellar system . according to her medical history and neurologic examination , we conducted a brain computed tomography ( ct ) under the impression of acute subarachnoid hemorrhage , but it was unremarkable . we hospitalized the patient , continued the supportive care and conservative management . until hospital day 5 we performed a cervical spine magnetic resonance imaging ( mri ) and found a large amount of subacute subdural hematoma on c7 to t4 level ( fig . 1 ) . we continued the supportive care as the patient had no neurologic deficit but only pain and the symptoms were gradually improved . it is usually related with following trauma , lumbar puncture , anticoagulant therapy , underlying neoplasm , arteriovenous malformation or rarely , with acupuncture4,7,9,11,12 ) . spontaneous ssdh is a rarer entity , but the etiology remains still unclear4 ) . in the spinal subdural space one theory is that the hemorrhage originates within the more vascular subarachnoid space , possibly after sudden raised intra - abdominal or intra - thoracic pressure3 ) . and others suggest that the subdural hematoma arises from ruptured small vessels on the inner surface of the dura10 ) . there has been some case reports and review of literatures dealing with diagnosis and treatment of the disease . most of patients present with pain , quadriplegia , paraplegia , sensory change or cauda equina syndrome3,4,5,7,9,11,12,13,14,15 ) . and , it is thus difficult to make the correct diagnosis at the very beginning if the patient has no history of trauma , related disease or treatment and do not show typical symptoms . it is often misdiagnosed as cerebrovascular accidents if the patient shows an unilateral involvement of motor or sensory disturbance11 ) . however , in some cases , ssdh may need surgical treatment and besides , in some cases , neurologic deficit can persist3,4,6,7,10,12,15 ) . therefore , it is important that clinicians make an impression for the the disease and an early diagnosis is essential for preventing irreversible paralysis or other neurologic deficits5 ) . but , like in this case , patients may show atypical symptoms and may be initially misdiagnosed . if the initial diagnostic work ups are unremarkable , clinicians should consider ssdh even when patients do not show typical symptoms corresponding to ssdh . once the clinician suspect the diagnosis of ssdh , mri is the preferred diagnostic method and ssdh appears as a space - occupying lesion , usually ventral , contained within the dura mater1,2 ) . in general , ssdh is a rare disease and known to be related to trauma . it is frequently associated with underlying coagulopathy in most patients or with those patients receiving anticoagulant or antiplatelet agent . but , ssdh can cause various symptoms and the patient may have no related disease or previous trauma history like in our case . moreover , delay of treatment due to misdiagnosis can lead the patient to have irreversible neurologic deficit . it is therefore very important for the clinicians to suspect the possibility of spontaneous ssdh even the patients do not have related disease or typical symptoms .
spinal subdural hematoma is a rarely reported disease and spontaneous spinal subdural hematomas ( ssdh ) without underlying pathological changes are even rarer . 
 the patients usually show typical symtoms such as back pain , quadriplegia , paraplegia or sensory change . but rarely , patients may show atypical symptoms such as hemiparesis and misdiagnosed to cerebrovascular accident . 
 we recently experienced a case of ssdh , where the patient initially showed vague symptoms , such as the sudden onset of headache which we initially misdiagnosed as subarachnoid hemorrhage . in this case , the headache of patient improved but the neck pain persisted until hospital day 5 . 
 therefre , we conducted the mri of cervical spine and finally confirmed ssdh . 
 the patient was managed conservatively and improved without recurrence . in this case report 
 , we discuss the clinical features of ssdh with emphasis on the importance of an early diagnosis .