BENIGN INTRACRANIAL HYPERTENSION

Dr.Syed Alam Zeb

Presentor

PoF Hospitals

CASE HISTORY

A 14 yrs. old boy presented to the Neurology deptt. LRH in March 2004 with the chief complaints of:

1. Headache---1 month2. Transient visual obscurations—1 month3. No hx. of fits, vomiting or fever Past hx.of meningitis 5-6 yrs ago. Hx of asthma and had used oral steroids for

long.

Case history cont.

On examination 14 yrs old boy with cushingoid face.

GPE :

Temp. 98.0 F

BP 120/80.

HMF intact.

No signs of meningism.

Cranial nerve examination revealed left lateral rectus palsy and diplopia on lateral gaze.

Fundi—bilateral papilloedema.Limb examination—normalSystemic examinationChest…few wheezes bilaterally.Heart and abdomen exam.unremarkable.

Immediate CT scan was done after the routine invetigation

CT SCANS

MRI and MRV brain was done which confirmed sagital sinus thrombosis and excluded SOL.

LP was planned after the visual perimetry.

LP showed a very high opening pressure of 400 mm of water.

CSF biochemistry was normal.

In view of the sagital sinus thrombosis the pt. Was screened for underlying hypercoagulable states. Protien C and S and anti-thrombin III levels were done.

Protein C and S were found to be significantly low.

So the diagnosis was pseudotumor cerebri with sagital and transverse sinus thrombosis due to underlying protein C and S deficiency

Withdrawal from chronic steroid therapy along with the history of meningitis could be the contributing factor.

Treatment given was:

Acetazolamide and oral anti-coagulants.

patient showed a good response in view of clinical improvement along with partial resolution of papilloedema.

The term pseudotumor cerebri designates a characteristic syndrome of:

HeadachePapilloedemaMinimal or absent focal neurologic signsAnd normal CSF composition.All occurring in the absence of enlarged ventricles or

an intracranial mass on CT or MRI.

Being a syndrome and not a disease pseudotumor cerebri has a number of causes or pathogenic associations. The most common form is benign or idiopathic intracranial hypertension.

BIHThe diagnostic criteria include :

Symptoms and signs restricted to those of elevated intracranial pressure;

Normal findings on neuroimaging studies, Excluding nonspecific findings of raised

intracranial pressure; Increased cerebrospinal fluid pressure with a

normal composition. The diagnosis of idiopathic pseudotumor cerebri

should not be accepted when the CSF content is abnormal

• IH literally means that the pressure of the CSF

that surrounds the brain is too high. Raised ICP is transmitted along the paths of the optic nerves, causing the nerves to swell (papilledema), which can lead to loss of vision and blindness.

NORMAL OPTIC DISC

PAPILLOEDEMA

PATHOPHYSIOLOGY

• The pathophysiology of this disorder is unclear.• Resent experience is converging on the

possibility that there is functional obstruction to outflow in the venous sinuses.

• Partial obstructions of the lateral sinuses (seen during the venous phase of conventional angiography).

• A relative resistance to the absorption of cerebrospinal fluid across the arachnoid villi is widely presumed to be present.

• Other theories support an abnormality in the cerebral circulation with a resulting increase in the brain's water content.

• Some say elevated level of vasopressin in the CSF but not in the blood.

PATHOPHYSIOLOGY CONT.

PATHOPHYSIOLOGY CONT.• The disease commonly occurs in women who are

overweight. Obesity has been proposed to increase intra-

abdominal pressure, which, in turn, raises cardiac filling pressures. This rise in pressure leads to impeded venous return from the brain with a subsequent elevation in intracranial venous pressure.

If not treated appropriately, chronic interruption of the axoplasmic flow of the optic nerves with ensuing papilledema due to this pressure may lead to irreversible optic neuropathy

CAUSES

• Most cases of pseudotumor cerebri occur in young women who are obese and, less frequently, in men who are otherwise healthy.

• If this disorder presents in an individual who is not overweight, ruling out associated risk factors is necessary.These risk factors include: Systemic diseases (including Lyme disease)Disruption of cerebral venous flow. Certain endocrine or metabolic disorders. Exposure to or withdrawal from certain exogenous substances.

• A myriad of illnesses are associated with idiopathic intracranial hypertension.

• The following diseases have been associated with idiopathic intracranial hypertension: anemia, chronic respiratory insufficiency, familial Mediterranean fever, hypertension, multiple sclerosis, polyangiitis overlap syndrome, psittacosis, renal disease, Reye syndrome, sarcoidosis, systemic lupus erythematosus, and thrombocytopenic purpura.

• Cerebral venous compression by extravascular tumors or secondary thrombosis results in impaired absorption of the cerebrospinal fluid and, thus, pseudotumor cerebri.

• Restriction of venous drainage from the head may be impaired with radical neck dissection, even if completed only on the right side (predominant drainage from the head is via the right jugular vein).

• Spontaneous recanalization usually occurs, but, if delayed, chronic papilledema may result.

• The main considerations in cases of raised and papilloedema in the absence of an intracerebral mass are:

1. Covert occlusion of the dural venous sinuses.

2. Gliomatosis cerebri

3. Occult arterio venous malformation

4. Carcinomatous, infectious or granulomatous meningitis.

1.OCCLUSION OF DURAL SINUSES

• Hedache • Papilloedema• Epilepsy

MRI + MRV – Reveal sup sagital lateral sinus thrombosis.

Isolated cortical vein thrombosis on the cerebral convexity does not cause pseudotumor.

2- A large cerrebral arterio venous malformation by increasing venous pressure and cerebra blood volume, can give rise to a pseudotumor syndrome.

3- Several diseases with raised CSF protein concentration have given rise to a pseudotumorsyndrome. Common ones being Guillain Barre Syndrome.Systemic lupusSpinal Tumor particularly oligodendroglioma

4- Toxic and metabolic disturbances.• In children withdrawl of chronic corticosteriod

therapy• Lead toxicity in children• Excessive doses of tetracycline and Vitamin A.

Particularly the isotretinoin form used in the treatment of severe acne.

5- Hypo or Hyperadrenalism6- Myxedema and hypoparathyroidism.7- Drugs

• Endocrine disturbances:

PREGNANCY is occasionally associated with idiopathic intracranial hypertension. This disorder can present at any stage of pregnancy.

• Given the limitations of neuroimaging studies and of medically treating patients who are pregnant, both the diagnosis and the management of these patients are determined on a case-by-case basis in conjunction with the patient's obstetrician

INCIDENCE• The incidence of BIH is variable from country to

country. Because of the relation of the disease to body habitus, its occurrence varies according to the incidence of obesity in the respective region.

A study performed in Libya demonstrated an incidence of 2.2 per 100,000 in the general population, 4.3 per 100,000 in women, and 21.4 per 100,000 in women who are overweight

American populations have the incidence of 0.9-1.0 per 100,000 in the general population. This incidence rate increases to 1.6-3.5 per 100,000 in women, and 7.9-19 per 100,000 in women who are overweight

Mortality/Morbidity

The morbidity of this disorder is mainly related to the effects of papilledema.

If left untreated, long-standing disc edema results in an irreversible optic neuropathy with accompanying constriction of the visual field and loss of color vision.

In end-stage papilledema, central visual acuity is also involved.

SIGNS & SYMPTOMS

1. The most common symptom is an unbearably painful headache that is not relieved by any medication. Some patients end up the emergency room, believing that they are suffering from the most severe migraine headache imaginable.

Signs/Symptoms cont.

2. The second most common symptom is transient altered vision particularly on movement, followed by intracranial noise (pulse synchronous tinnitus). Other symptoms can include stiff neck, back pain, double vision, pain behind the eyes.

PHYSICAL EXAMINATION• The most significant finding in patients with this

disease is bilateral disc edema secondary to the increased intracranial pressure.

• This papilledema varies from patient to patient and is indistinguishable from optic nerve swelling caused by intracranial space-occupying lesions.

• In more pronounced cases of disc swelling, macular involvement with subsequent edema and diminished central vision may be present.

• High-grade and atrophic papilledema in addition to subretinal hemorrhages are poor visual prognostic signs.

PAPILLOEDEMA

Physical exam. Cont.• In some instances, the disc swelling is asymmetric.• If left untreated, chronic disc swelling eventually

leads to clinically significant visual loss. • Although all patients present with enlarged blind

spots during their initial perimetry, uncontrolled papilledema results in progressive peripheral visual field constriction or nerve fiber bundle defects (eg, nasal depression, nasal steps, arcuate scotomas).

• The central visual field is affected in end-stage chronic papilledema

Physical Exam. Cont

• Sudden loss of central vision may result from an associated anterior ischemic optic neuropathy, a vascular occlusion, or an associated subretinal neovascular membrane.

• The diplopia noted in patients with idiopathic intracranial hypertension is invariably due to unilateral or bilateral sixth nerve palsy. These cranial nerve palsies diminish with the lowering of the intracranial pressure.

• Occasionally, patients with diplopia present with oculomotor or trochlear nerve palsy

DIFFERENTIALS• Bilateral optic nerve head edema is presumably due to

increased intracranial pressure secondary to an intracranial tumor until proven otherwise. Ruling out malignant hypertension prior to pursuing the diagnostic trail of pseudotumor cerebri is always worthwhile.If the patient's blood pressure is normal or minimally to moderately elevated, obtaining urgent neuroimaging studies to rule out a space-occupying lesion or a dural sinus thrombosis is essential. If the neuroimaging study does not demonstrate any pathology and if a lumbar puncture demonstrates a raised opening pressure, then one of the above-mentioned causes of increased intracranial pressure must be considered

Differentials cont.

• Other causes of bilateral raised discs include the following:PseudopapilledemaDrusen of the optic nerve headsMalignant hypertensionBilateral infiltrative/infectious/inflammatory optic neuropathyBilateral anterior ischemic optic neuropathyBilateral optic nerve papillitisBilateral optic nerve tumors (eg, glioma, meningioma)

WORK UP• Neuroimaging• A patient with bilateral disc swelling should

undergo urgent neuroimaging studies to rule out an intracranial mass or a dural sinus thrombosis.

• Although CT is certainly adequate in most instances, MRI and MRV are effective in ruling out both a mass lesion and a potential dural sinus thrombosis.

• In the setting of idiopathic intracranial hypertension, the findings on neuroimaging studies either are normal or demonstrate small slitlike ventricles, enlarged optic nerve sheaths, and occasionally an empty sella.

Work up cont.

• Ultrasonography Standardized A-scan orbital ultrasonography

precisely measures the diameter of the optic nerve sheath.

If this diameter increases in primary gaze and diminishes by 25% in eccentric gaze (30° test), then increased subarachnoid fluid surrounding the optic nerve is presumably present. This finding is consistent with papilledema if it is bilateral.

LUMBAR PUNCTURE

Lumbar Puncture

• Once an intracranial mass lesion is ruled out, a lumbar puncture is indicated. The opening pressure should be measured with the patient relaxed to avoid a falsely elevated pressure reading.

• Unfortunately, some patients demonstrate a transiently normal pressure despite their harboring idiopathic intracranial hypertension. Confirming the disease in these patients is difficult.

• Besides the value of the opening pressure, the clarity and the color of the cerebrospinal fluid should be noted. In addition, the cerebrospinal fluid should be forwarded for assessment of the cell count, cytology, culture, glucose, protein, and electrolyte concentration. All of these findings are normal in patients with pseudotumor cerebri

• Cessation of exogenous agents related to increased intracranial pressure

• Use of diuretics to control the intracranial pressure • To protect the optic nerve function, the intracranial pressure must be

lowered. • Acetazolamide appears to be the most effective diuretic in lowering the

intracranial pressure. The initial dose should be 1 g/d. taken as 500mg bd or 250 mg taken 4 times per day. This dose can be increased to 2 g/d, although most patients do not tolerate the troubling adverse effects (eg, extremity paresthesias, fatigue, metallic taste when drinking carbonated beverages, decreased libido) of this medication at this high dose.

• In the event of intolerance to acetazolamide, furosemide may be used as a replacement diuretic in this group. Unfortunately, furosemide does not appear to be as effective as acetazolamide.

TREATMENT

• Corticosteroids

Corticosteroids are effective in lowering the intracranial pressure in those patients with an inflammatory etiology for their idiopathic intracranial hypertension.

In addition, steroids may be used as a supplement to acetazolamide to hasten recovery in patients who present with severe papilledema.

Because of the significant adverse effects, corticosteroids should not be considered as a long-term solution for these patients

TREATMENT

• Surgical Care: • Patients with idiopathic intracranial hypertension should be

closely monitored while on medical treatment. • The frequency of visits is determined by the initial state of the

patient's visual function and the response to medical treatment.• Despite close follow-up care and maximum medical treatment,

some patients experience deterioration of their visual function.• In this situation, surgical intervention should be considered. Two

procedures that can be performed are optic nerve sheath fenestration or a cerebrospinal fluid diversion procedure (lumboperitoneal or ventriculoperitoneal shunt). Treatment of this disorder by repeated lumbar punctures is considered to be of historic interest

Treatment cont.• Optic nerve sheath fenestration Optic nerve sheath fenestration has been demonstrated to result in the

reversal of optic nerve edema with some recovery of optic nerve function. The approach to the optic nerve may be from the medial or lateral aspect of the orbit; each technique has its benefits and drawbacks.

Occasionally, a bilateral curative effect of the papilledema occurs from unilateral surgery. However, if this is not the case, then the opposite nerve must undergo the same procedure.

Although the intracranial pressure remains elevated in these patients postoperatively, the local filtering effect of the fenestration acts as a safety valve and eliminates the pressure from being transmitted to the optic nerve.

Complications related to this procedure include diplopia, optic nerve injury, vascular occlusion, a tonic pupil, and the inherent risk of hemorrhage and infection with intraconal surgery.

Unfortunately, Spoor has demonstrated that the long-term success rate of this operation may be only 16%.

Treatment cont.

• Cerebrospinal fluid diversion procedures (lumboperitoneal and ventriculoperitoneal shunt)These two neurosurgical interventions are highly effective in lowering the intracranial pressure. In some facilities, they remain the procedures of choice for treating patients with idiopathic intracranial hypertension who do not respond to maximum medical treatment.Shunts are also indicated in the following: patients with intractable headaches, regions where no access is available to a surgeon who is comfortable with optic nerve sheath fenestration, and patients with a failed optic nerve sheath fenestration

Diet: Weight reduction has been clearly demonstrated to be an

important factor in the long-term management of these patients.

As little as a 6% decrease in the total body weight can result in the resolution of papilledema. Unfortunately, weight loss in patients who are obese is difficult.

A referral to a dietitian is worthwhile in patients who are motivated to lose weight.