Idiopathic Intracranial Hypertension Shunting

About Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH), sometimes referred to by an old name, 'pseudotumor cerebri (PTC),' is a chronic neurological disorder, which can mimic the symptoms of a brain tumor.

IIH is characterized by increased intracranial pressure with no evidence of intracranial mass, hydrocephalus, infection, or hypertensive encephalopathy. It is a diagnosis made by systematically ruling out other disorders. The Modified Dandy Criteria is used to assist physicians in establishing the diagnosis.

Epidemiology

Within the general population, approximately 1 – 2 people in 100,000 suffer from IIH.² Among obese women of childbearing age, the incidence is 19 – 21 in 100,000 people,³ although anyone can develop the condition regardless of age, gender, weight, or ethnicity. The incidence of IIH is increasing most likely due to rising rates of societal obesity, greater patient and physician awareness of the disorder, and improved diagnosis.⁴

Symptoms and Diagnosis

Your patient may present with the following symptoms:

• Migraine-type headaches, unrelieved by medication, which may be worse in the morning (the most common symptom)
• Dizziness
• Nausea
• Transient visual obscurations characteristic of papilledema
• Papilledema causing impaired vision, especially peripheral visual field defects and enlargement of the blind spot
• Photophobia
• Pain behind the eyes or when moving the eyes
• Pulse synchronous tinnitus (described as a swooshing sound in sync with the patient’s heartbeat)
• Tinnitus
• Hearing loss
• Shoulder, back, and/or neck pain
• Ophthalmoplegia (paralysis of extraocular muscles)

There are four criteria for diagnosing IIH (Modified Dandy Criteria)⁵:

1. High intracranial pressure (ICP). Cerebrospinal fluid (CSF) pressure of more than 25 cm H₂0,⁶ although pressures of more than 40 cm H₂0 are not uncommon
2. Normal composition of CSF
3. Papilledema and headaches with no focal findings (In a small percentage papilledema is not always present)
4. Normal CT or MRI with the exceptions of slit ventricles, partial or total empty sella, or alterations in cerebral venous sinus visualized by MRI venography or cerebral angiography

Shunting for Idiopathic Intracranial Hypertension

Shunting has been in practice for the treatment of idiopathic intracranial hypertension (IIH) for many years. The use of a lumboperitoneal shunt is indicated in patients with IIH for whom lifestyle changes and oral medication have not fully relieved the patient’s symptoms.³ In these cases shunting, especially shunting with an adjustable valve, may successfully treat the condition while diminishing associated hypotension (low pressure).

About Strata^TM NSC Lumboperitoneal Shunts

Shunts typically consist of two catheters and a valve that redirects excess cerebrospinal fluid (CSF) from the brain’s ventricle to another part of the body, most often the peritoneal cavity (ventriculoperitoneal shunt). In the case of IIH, a lumboperitoneal shunt moves fluid from the lumbar subarachnoid space to the peritoneum where it is absorbed by the body.

The Strata valve advantage is that the pressure/flow performance level setting can be noninvasively adjusted after implantation to the unique CSF pressure needs of each person.

More information about the Medtronic Strata^® NSC LP shunt can be found here.

The Strata NSC LP Valve