Spontaneous Intracranial Hypotension (SIH)
Severe, persistent headaches can have a rare and often overlooked cause: a spinal cerebrospinal fluid leak.
In spontaneous intracranial hypotension, cerebrospinal fluid can leak through a small defect in the dura along the spine. This disrupts normal pressure regulation between the spine and the head and may cause a range of symptoms and complications.
“Spontaneous” means that there is no direct trigger or cause, such as a bone fracture, sneazing, or accident.
“Intracranial hypotension” describes low pressure inside the head caused by a loss of cerebrospinal fluid (CSF) at the spine.
There are different types of spinal CSF leaks, but they all disturb the delicate fluid balance between the spine and the head. When a person stands up, this imbalance can cause a shift of fluid away from the head and trigger symptoms. Headache is the most common complaint, but SIH is often much more than “just a headache”.
Untreated spinal CSF leaks can become chronic and may be associated with complications such as chronic subdural hematoma, sinus vein thrombosis, hearing damage, superficial siderosis, spinal cord herniation, and very rarely - coma.
Current estimates suggest that SIH affects 4 to 5 people per 100,000 population each year. However, experts at the Freiburg CSF Center emphasize that many cases likely remain undiagnosed. As a result, patients are often either not diagnosed at all or are misdiagnosed and treated for migraine, fatigue, or somatization disorder.
Symptoms
Most patients with SIH experience headaches, often located in the back of the head and neck. These headaches typically occur or worsen when standing upright. When lying down, the symptoms often improve significantly or disappear completely.
In addition, there are many different accompanying symptoms, including nausea, vomiting, dizziness, hearing and vision disturbances, sensory disturbances, sensitivity to noise and light, "brain fog", concentration difficulties, and many more. Symptoms often change over time and may not be equally severe every day.