Intracranial hypotension syndrome

Characterized by orthostatic headache that may be exacerbated by laughing, coughing or other Valsalva maneuvers.

Spontaneous intracranial hypotension is characterized by lower than normal volume of CSF because of leakage through the dural membrane at one or multiple sites.

The loss of CSF causes displacement of cerebral structures, manifesting by headache and other neurologic symptoms.

The term spontaneous indicates a differentiation of CSF leaks of known cause such is cranial spinal trauma, spinal surgery, or lumbar puncture or spinal anesthesia.

May be associated symptoms with orthostasis including nausea, vomiting, dizziness, diplopia, blurry vision, and tinnitus.

The annual estimated incidence is 4 to 5 cases per hundred thousand population, about half the incidence of aneurysmal subarachnoid hemorrhage.

It can occur at any age including children and adolescents but women between the ages of 35 and 55 years a most often affected.

Diagnosis supported by the demonstration of decreased CSF opening pressure on lumbar puncture.

CSF pressure in this disorder may be measured as normal, however it is often lower than normal between 6 to 25 cm of water or 4.4 to 18.4 mmHg, and the term hypotension persists.

Spontaneous intracranial hypotension is a treatable cause of headache and other manifestations such as dizziness, mental dullness, behavioral change, all of which however are subject to clinical variability making diagnosis difficult.

There are however cases of spontaneous intracranial hypotension with normal CSF opening pressures.

CSF analysis may be normal or may show elevated protein concentration, with values greater than hundred milligrams per deciliter.

The most common identifiable cause of spontaneous intracranial hypotension is a CSF leak within the spinal column.

The downward displacement of cerebral structures and traction or distortion of pain sensitive nerve endings in the cranial dura and its vasculature account for the underlying headache and neurologic findings.

Skull based CSF leakage from the posterior cranial fossa into the neck may rarely cause spontaneous intracranial hypotension, but such leaks resulting in CSF rhinorrhea or otorrhea are not related.

Three types of spontaneous spinal CSF leaks have been identified by imaging of the spine and intraoperative observations: type I due to a linear tear in the dura located ventral to or posterior lateral to the spinal cord.

A second type is associated with leakage at simple meningeal diverticula (Tarkovsky cysts) or with diffuse dilatations of the dural sac as occurs in ankylosing spondylitis.

A third time has been attributed to spinal CSF venous fistula with your abnormal communications between the CSF containing spinal subarachnoid space and adjacent veins.

Rarely connective tissue disorders such as Marfan syndrome or Ehler”s-Danlos syndrome’s may facilitate rents  in the dura resulting in spontaneous intracranial hypotension.

Spinal osteophytes or calcified disc herniations could also penetrate the door closing the door I’ll tear resulting in a virtual spinal leak.

The most common MRI abnormality is diffuse pachymeningeal enhancement.

MRI imaging findings include decreased size of the ventricular system, engorged rural venous sinuses and subdural hygromas.

Can be a spontaneous or iatrogenic process.

Its cardinal symptom is spontaneous intracranial hypertension headache and worsens on standing in subsides with lying down.

Spontaneous disease is thought to be secondary to persistent CSF leak or decreased production.

In patients with intraventricular shunt device overdrainage complications are common and can lead to the syndrome.

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