Spontaneous intracranial hypotension (SIH): The early appearance of urinary bladder activity in RI cisternography is a pathognomonic sign of SIH?

Abstract

Spontaneous intracranial hypotension (SIH) is a rare but increasingly recognized pathophysiological entity. It is a syndrome of low CSF pressure due to CSF leakage. This usually associates with postural headache which characteristically become worse when sitting or standing, and often ameliorates completely by lying flat. This could be caused by minor head trauma, vigorous exercise or a violent bout of coughing. In a clinical situation, it is sometimes difficult to differentiate it from other headache accompanying disease such as subarachnoid hemorrhage or chronic subdural hematome because of its wide range of presenting symptoms. Characteristic neuroradiological findings have been well documented in the literature. MR imaging includes dural enhancement, subdural fluid collection and downward displacement of the cerebellar tonsils. Radiosotope (RI) cisternography, CT myelography and recently MR myelography are studies of choice to detect CSF leakage. Lumbar CSF pressure in usually below 60 mmH2O and this can be assured by pressure monotoring. Radioisotope (RI) cisternography findings are characterized by rapid clearance of the RI from the CSF space and early RI filling of urinary bladder. However, the changes of RI cisternography findings in the post-treatment state are still not fully understood. We herein report three cases who presented with severe postural headache diagnosed as SIH. In each case, symptoms and MR imaging findings resolved after treatment, except the early visualization of urinary bladder activity in RI cisternograhy. Therefore, we believe that this finding may not be pathognomonic in SIH.