Spontaneous Intracranial Hypotension is a severe headache disorder caused by leakage of cerebrospinal fluid into the spinal canal.
Since the first lumbar punctures were performed in the 1800's it has been known that low pressure headaches could occur as a result of persistent cerebrospinal fluid leakage at the site of a spinal needle insertion.
However, this unusual headache disorder can arise without a provoking medical procedure.
Spontaneous Intracranial Hypotension probably affects about 50 people per million every year.
It now appears that cerebrospinal fluid leaks can occur spontaneously, usually from areas of weakness in the meningeal lining of nerve roots in the spinal canal (called cervical or thoracic root diverticula).
To make a diagnosis, it is important the condition is specifically considered by the clinician and that the radiologist is aware that you suspect this condition.
The changes of low pressure can be subtle and require MRI Brain with gadolinium injection to see pachymeningeal enhancement. A plain or contrast enhanced CT Brain will not show changes.
Diagnosis relies on a history of a postural headache, also called orthostatic headache.
A postural headache is one that is better on lying flat and is worse on standing.
There is a phenomenon called "second half of day" headache. These people are OK on rising in the morning, but as the day proceeds a worsening headache occurs, which is once more relieved by lying flat.
The criteria for diagnosis of spontaneous low pressure headaches have recently been revised by Schievink, Maya and Moser (2008).
Apart from postural headache, there are other symptoms of loss of cerebrospinal fluid. As low pressure headaches can be treated with epidural blood patch, it is important to recognise these symptoms:
Many people with this condition settle without treatment, but if your symptoms have persisted for more than a couple of weeks or are so disabling that you cannot function, then the best treatment is called an Epidural Blood Patch.
In an Epidural Blood Patch, blood is drawn from you arm (under sterile conditions) and injected into your lower back (to the 'epidural space').
This injection increases the stiffness of the spinal canal and the brain is less likely to sag down and stretch the sensitive lining of the brain.
When the brain is better supported, there is less headache.
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If there are no references listed, please notify me, as this box should contain a list of information sources, or a link to a 'Systematic Review' of the topic discussed on this page.
B Mokri et al. Syndrome of orthostatic headaches and diffuse pachymeningeal gadolinium enhancement. Mayo Clinic Proceedings 1997;72:400-413.
B Mokri and JB Posner. Spontaneous intracranial hypotension : The broadening clinical and imaging spectrum of CSF leaks. Neurology 2000;55:1771-2
WI Schievink. Spontaneous Spinal Cerebrospinal Fluid Leaks. Cephalalgia, 2008, 28, 1347–1356