Abbas Ghorbani - Neurology Department of Isfahan University of Medical Sciences

Introduction:Low cerebrospinal fluid (CSF) pressure headache is caused by an internal spinal fluid leak and may range from obvious and disabling to subtle and nagging.When the pressure of this fluid is too low typically when there is a small leak somewhere in the meninges. the brain may sag downward when the patient is upright, stretching the meninges and nerves lining the brain and causing pain.The classic symptom is a headache that becomes severe when the patient is upright and quickly disappears when the patient is lying flat. In most cases, there is an obvious cause of the leak, such as a spinal tap, spinal surgery, or trauma to the head or neck. In cases when postural headaches develop shortly after an obvious potential cause, diagnosis is usually easy to make. Subtle cases can be trickier to diagnose. There may be no obvious precipitating event, or perhaps the leak was caused by a sneeze, a violent cough, or some other unrecognized minor trauma. Some patients— particularly those with hyperflexibility of the joints — may be born with meninges that are more susceptible to tearing with relatively small degrees of force.Methods: lumber puncture (LP) is only helpful for diagnosing if the CSF pressure is low(<60mmCSF)Brain MRI with injected contrast dye may reveal enhancement of the meninges lining of the brain and sometimes indicate evidence of the brain sagging downward from the skull toward the neck. MRI of the neck and back occasionally reveals spinal fluid leaking out of its normal location.Computed tomography (CT) myelogram (a CT scan of the back after dye is injected into the spinal fluid) may reveal the site of the leak directly.CSF cisternogram — a procedure in which a radioactive dye is injected in the spinal fluid and detected by a special radiation-detecting camera — may reveal the leak directly, or may only show indirect evidence of the leak s presence but not its exact location.Results:The four main causes of CSF leaks are medical procedures; whiplash; bony, sharp calcifications penetrating the dura; and genetic disorders of connective tissue LP opening pressure is 34% of patients was 60 mm or less,45% - 60mm and 120 mm, 16% had 120 and 200mm.5% had > 200 mm. thus the most patients with this syndrome have normal CSF pressures.. Brain MRI with injected contrast dye may reveal enhancement of the meninges lining of the brain and sometimes indicate evidence of the brain sagging downward from the skull toward the neck. MRI of the neck and back occasionally reveals spinal fluid leaking out of its normal location.Cranial MRI changes of low CSF pressures are presence of subdural fluid collection, enhancement of the pachymeninges, or sagging of the brain. Other MRI findings are sella /pituitary usually enlarged complex narrowed and straight Discussion: neurologist frequently challenged by patients with headache who lack the typical clinical signs or imaging features of the low intracranial pressures . at least 25% of patients have and over half have a normal LP opening pressure. Detailed history taking will often give clues that suggest a CSF pressure disorder. That said misdiagnosis can lead to significant morbidity and inappropirate therapy. Anontargeted, autologous, high volume epidural blood patch is often the first step in management, and each attempt is successful approximately 30% of the time. Adisagreement exists regarding whether this procedure should be tried empirically or whether patients should be evaluated to determine the leak site first.Webb et al conducted a study to evaluate headaches in patients who had a known wet tap (ie, unintentional dural puncture) after a labor epidural. The researchers reviewed quality assurance data in an obstetrics anesthesia division and identified 40 patients who had known wet taps and 40 controls who had received an epidural without a wet tap during the same week and were matched for age and weight. Investigators contacted patients between 12 and 24 months later (mean, 18 months) and asked them about the incidence of chronic headache. The incidence of chronic headache in controls was 5% versus nearly 30% in patients who had had a wet tap.Summary: once a leak has been succesfully treated, the prognosis is generally good. However, leaks can recur, and new leaks may develop, particulaly in patients with underlying connective tissue disorders.