Spontaneous Intracranial Hypotension
What is it?
Spontaneous Intracranial Hypotension (SIH) is a condition that is characterized by low cerebrospinal fluid (CSF) pressure in the brain, typically without any known cause. It often results from a spontaneous cerebrospinal fluid leak, which reduces the fluid volume and pressure cushioning the brain and spinal cord. This condition is relatively rare and more common in women than men.
Symptoms
The primary symptom of SIH is a headache, which has distinctive characteristics. These include worsening headaches when standing or sitting upright and improving when lying down. Additional symptoms can include neck stiffness, nausea, vomiting, dizziness, changes in hearing (such as tinnitus), and sometimes visual disturbances or photophobia (sensitivity to light). In severe cases, SIH can lead to brain sagging, leading to more serious complications such as cranial nerve palsies, altered consciousness, or even coma.
Diagnosis
Diagnosing SIH can be challenging, but it generally involves a thorough medical history and physical examination, focusing on the nature and pattern of the headache. Imaging studies, such as an MRI of the brain and spine, may show findings indicative of low cerebrospinal fluid pressure, such as brain sagging, engorgement of venous structures, or dural enhancement after contrast administration. CT myelography may also be used to locate the exact site of cerebrospinal fluid leakage if MRI does not identify it. Lumbar puncture is another diagnostic tool, but it is often avoided as it can worsen symptoms.
Treatment
Treatment for SIH is often tailored to the individual. It may include initial conservative management, which usually involves bed rest, hydration, and caffeine intake, as caffeine can increase cerebrospinal fluid production. The most common and effective treatment is an epidural blood patch, which involves the injection of the patient’s own blood into the epidural space of the spinal column to clot and seal the leak. Surgery may be necessary if conservative measures and epidural blood patches are unsuccessful, and the exact leak site is identified. Pain management is essential and may include analgesics.
The prognosis for SIH is generally good, especially with prompt and appropriate treatment. Many patients experience symptom resolution with conservative treatments or after an epidural blood patch. However, some patients may require multiple treatments, and a small number may have recurrent or persistent symptoms. Early diagnosis and treatment are crucial for preventing complications and improving outcomes.