Definition and Overview
Spontaneous intracranial hypotension (SIH) is a disease in which intracranial pressure decreases due to leakage of cerebrospinal fluid from the spinal cord without trauma or procedures such as lumbar puncture. As the amount and pressure of cerebrospinal fluid decrease, the brain sags down and pain-sensitive structures are pulled, causing headaches. It is characterized by orthostatic headaches that worsen when standing up and improve when lying down.
cause
It is caused by leakage of cerebrospinal fluid due to a defect in the dura mater surrounding the spinal cord. It is related to weak areas of the dura, microscopic defects around the spine, and weakening of connective tissue, and occurs spontaneously without obvious trauma.
symptoms
Orthostatic headache is the most characteristic symptom. The headache occurs or worsens within a few minutes when you stand up, and is relieved when you lie down again. Headaches mainly appear in the back of the head and may spread to the neck and shoulders. It may be accompanied by neck pain and stiffness, tinnitus, hearing changes, nausea, and dizziness. As the course progresses longer, it may turn into a chronic headache with no obvious changes in posture.
diagnosis
The diagnosis of orthostatic headache is made by combining the history and imaging findings.
- Brain MRI: Diffuse dural contrast enhancement is a typical finding suggesting intracranial hypotension, and may be accompanied by pituitary discharge, subdural fluid retention, and venous sinus dilatation.
- Spinal cord imaging: Spinal cord MRI and CT myelography are used to find areas of cerebrospinal fluid leakage.
- Lumbar puncture: In some cases, the cerebrospinal fluid opening pressure is low, but in other cases it is within the normal range, so it is interpreted together with imaging findings.
treatment
Many patients improve with conservative treatment such as bed rest, fluid intake, and caffeine. If the patient does not respond to conservative treatment, epidural blood patch surgery is effective. This is a method of blocking the leakage site by injecting the patient's own blood into the epidural space, and can be repeated if there is no improvement the first time.
If symptoms persist despite blood suturing or if the leak area is clear, consider fibrin adhesive injection or surgical reconstruction.
Clinical implications
A headache that worsens when standing up and improves when lying down is a key clue suggesting spontaneous intracranial hypotension. If orthostatic headache is accompanied by dural contrast enhancement on brain MRI, the leak site must be actively searched for and treated.