Acute spinal cord compression usually results from trauma, infection, or cancer. Spinal subdural hematoma is an uncommon cause of spinal cord compression that occurs after spine trauma or spinal invasive procedure, especially in context of coagulopathy. In the following reported case, an 82-year-old woman with a history of rapidly progressive paraparesis after a sudden middle back pain, with no previous trauma or coagulopathy, due to an acute spontaneous spinal subdural hematoma. In fact, the main difficulty was to determine, in an emergency situation, the right strategy to identify both the lesion and its cause to adapt therapeutics. This case not only provides an illustrative unusual condition in an emergency department but also a challenging discussion to choose the right treatment for a sudden neurological impairment. According to a literature review of the idiopathic cases of spinal subdural hematomas without coagulopathy, the clinical outcome depends on severity of neurological impairment. MRI is the main examination to perform in an emergency. Thus surgical evacuation should be performed in emergency in patients presenting with severe neurological impairment.