Spontaneous intracranial hypotension

SIH is a condition characterized by a decrease in CSF pressure, often due to a CSF leak, which can occur spontaneously or secondary to trauma.

The pathophysiology of SIH involves the leakage of CSF, leading to a reduction in CSF volume and ICP. This can cause the brain to sag, leading to traction on pain-sensitive structures and resulting in symptoms such as orthostatic headache, neck pain, and dizziness.

The incidence of SIH is estimated at 5 per 100,000 person-years, with a peak incidence at 40 years and women being affected twice as often as men.

Risk factors for SIH include connective tissue disorders, minor trauma, and certain medications. However, in many cases, the cause of the CSF leak remains unknown. In approximately 50% of cases, the location of the spinal CSF leak remains undetectable.

The clinical course of SIH varies. Patients generally present with headaches that start after standing, sitting, straining, or coughing, often relieved by returning to a seated or lying position. Other associated symptoms may include neck pain, back pain, headaches, dizziness, and nausea. While some patients may experience spontaneous resolution of symptoms, others may have debilitating presentation.

The prognosis of SIH is generally favorable with appropriate management. While the condition can be debilitating, many patients experience symptom improvement or resolution with treatment. Outcomes can vary, and some patients may experience continued or recurrent leaks with chronic symptoms.