W Most patients who receive treatment for intracranial hypotension do well, with improved quality of life or complete cure. W
Diagnosis
The diagnosis of intracranial hypotension relies primarily on the symptoms and history of the patient. The positional aspect of the headache is a key feature in most, but not all, cases. A patient may report a recent history of a lumbar puncture, epidural anesthesia or injection( s), surgery, or trauma. A previous diagnosis of postural orthostatic tachycardia syndrome( POTS) is not uncommon. POTS refers to a condition in which moving from a lying to standing position causes an abnormal increase in heart rate and a range of other signs and symptoms. A patient’ s positional symptoms may be due to POTS or due to a spinal CSF leak or both. Underlying inherited disorders of connective tissue( Marfan syndrome,
DIAGNOSTIC CHALLENGES
• low awareness contributes to delayed diagnosis and misdiagnosis
• not every headache due to intracranial hypotension is positional
• not every positional headache is due to intracranial hypotension
• not every patient with intracranial hypotension has a headache
• common and uncommon presentations and findings may not be recognized as secondary to intracranial hypotension( subdural hematomas, tremor, unsteady gait, dementia, low lying cerebellar tonsils, coma, stroke, spinal cord manifestations)
• normal CSF pressures are not uncommon
• imaging interpretation requires experience and training
• brain MRI is normal in ~ 20 %
• spinal imaging is negative in ~ 50 %
• more than one type of spinal imaging is often needed
Ehlers-Danlos syndromes, others) may or may not be recognized prior to the onset of symptoms related to a spinal CSF leak. A few patients may have received a diagnosis of Chiari I due to the brain imaging finding of low-lying cerebellar tonsils( part of brain at back of head). Chiari I is a congenital condition in which the back part of the skull is abnormally small or misshapen, and part of the brain, the lower part of the cerebellum, extends into the spinal canal. In intracranial hypotension, the finding of low lying cerebellar tonsils and brain sag is due to the loss of CSF volume and is reversible with treatment of the leak, so it is often called pseudo- Chiari. It can be challenging for clinicians to sort out if this finding on brain imaging is from congenital Chiari or from low CSF volume of intracranial hypotension or from a combination of both. Minimal response to medications used for migraines can be an additional clue to the diagnosis.
A diagnostic lumbar puncture to determine pressure measurement or CSF analysis is not usually performed unless another disorder such as meningitis is being ruled out. Minor CSF abnormalities may be noted and cerebrospinal fluid pressure may be low, normal, or even high.
An MRI of the brain with contrast should be done in all suspected cases to determine several classic findings although imaging findings are absent in about 20 % of patients. Spinal imaging is used to locate leaks or other abnormalities for targeted treatment – but may be negative in up to one-half of suspected cases due to the limits of sensitivity. A full spine MRI without contrast is often the initial choice because the testing is non-invasive. Myelography, which involves lumbar puncture for the injection of contrast, uses CT, MR, or digital subtraction techniques. More than one type of spinal imaging is often needed.
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