150 Pseudotumor cerebri

Pseudotumor cerebri

Youmans,Neurological surgery 6th editionChapter 150Neil R Miller

07/03/59

Terminology

• pseudotumor cerebri (PTC)• idiopathic intracranial hypertension (IIH)• secondary pseudotumor cerebri for the rare cases

in which a cause (e.g., drug induced) is identified

Terminology

• increased intracranial pressure (ICP) without evidence of dilated ventricles or a mass lesion by imaging

• normal cerebrospinal fluid (CSF) content• papilledema occurring in most cases (but not all)• young, obese women without any clear

explanation

Epidemiology

• infants, children, and young adults• 90% of cases, is typically a disorder of obese

females of childbearing age

Symptoms and Signs

• Asymptomatic and discovered during a routine ophthalmic examination when papilledema is found

• Headache(90%)– generally different from previous headaches and is

severe– bifrontal or generalized, pressure-like, and often

associated with neck pain– migrainous features, including unilateral pain, nausea,

vomiting, photophobia, and phonophobia– “brain tumor headache” that is worse in the morning

and aggravated when cerebral venous pressure is increased by valsalva maneuvers (e.g., coughing, sneezing)

Symptoms and Signs

• Transient obscurations of vision (TOVs)(70%)– partial or complete– unilateral or bilateral– few seconds– precipitated by a change in posture (e.g., bending

over, arising from a stooped position) or rolling the eyes

– indicate the presence of optic disc swelling– not a sign of a poor prognosis

• Visual loss– enlarged dark spot in the temporal visual field

Symptoms and Signs

• Diplopia(40%)– horizontal diplopia– results from unilateral or bilateral abducens nerve

paresis– nonlocalizing feature of increased ICP

• Pulsatile tinnitus : uncommon – whooshing sound, hearing a heartbeat in the head, or a

high-pitched noise– reflect flow disturbances within the cerebral venous

system– unilateral or bilateral– often more prominent at night or in quiet surroundings

Symptoms and Signs

• Papilledema– diagnostic hallmark– almost always bilateral and symmetrical but it may be

asymmetric or, occasionally, unilateral– crucial in determining the appropriate management of

any patient with papilledema

Frisen Scale

Diagnosis

• no intracranial or spinal mass• no evidence of hydrocephalus– MRI is recommend

• documented increased ICP– Normal lumbar CSF pressure in both obese and

nonobese adult : 20-25 cmH2O– Prepupertal : greater than 20 cmH2O is abnormal– monitoring

• normal CSF contents – glucose and protein concentration, presence of cells,

cytology, and atypical infections (e.g., syphilis, cryptococcus, fungus)

Secondary Pseudotumor cerebri

Secondary Pseudotumor cerebri

Complication

• Permanent visual loss• CSF pressure remained elevated

Pathophysiology

• Unclear mechanism,both IIH or secondary PTC• Plasma levels of ghrelin– a hormone that appears to be involved in the regulation

of body weight– found no difference between obese patients with and

without evidence of IIH

Monitoring

• Visual field defect– Similar to that occurring in patients with chronic open-

angle glaucoma– progressive visual field constriction, color vision loss,

and finally, loss of central vision• Most visual deficits associated with papilledema

are reversible if ICP is lowered before severe visual loss or optic nerve ischemia develops

• Ophthalmologist

Monitoring

Monitoring

• At disease onset, some patients require an evaluation every 1 to 2 weeks until a pattern of progression or stability is established

• Other patients can be examined every 1 to 3 months without fear that they will lose vision in the interim

• Patients with stable vision and mild or moderate papilledema may need to be examined only every 4 to 12 months

Treatment

• Neurologist, ophthalmologist, primary care physician, and neurosurgeon

• Presence and severity of symptoms such as headache• Degree of visual loss at initial examination• Rate of progression of visual loss• Presence of an identifiable underlying cause (e.g.,

medication induced, venous sinus thrombosis, Chiari malformation)

• Detection of factors known to be associated with a poorer visual prognosis(e.g., African American heritage, pubescent child, male gender, high-grade papilledema with macular edema)

Treatment Related to Obesity

• Weight loss, restrict food and exercise• Decreasing food intake while increasing water

consumption and sodium restriction• When weight loss efforts fail, bariatric surgery may

be considered• Weight reduction should not be used as the only

treatment in patients with PTC

Medical Treatment

• Most appropriate when the primary problem is headache in the setting of good visual function

• Carbonic anhydrase inhibitors– decrease the production of CSF and thereby result

in decreased sodium ion transport across the choroidal epithelium

– mild diuretic effect– dose of 1 g/day given in divided doses of either 250 mg

four times a day or 500-mg Sequels twice a day– maximum dose 4g/day– side effect : paresthesias of the extremities, lethargy,

and altered taste sensation

Medical Treatment

• Repeated Lumbar Puncture– “high-volume” LP, with removal of 20 mL of CSF or more– low-pressure headaches may develop after this

procedure in patients in whom this is done– Pressure into the normal range (target closing pressure

range of 14 to 18 cm H2O)

Surgical Procedures

• Severe optic neuropathy or when other forms of treatment have failed to prevent visual loss

• It is not recommended for the treatment of headaches alone

Surgical Procedures

• Cerebrospinal Fluid Diversion Procedures– In the past : lumboperitoneal shunt– Often malfunction and infection– Now : stereotactic devices for place shunt– Complication• spontaneous obstruction of the proximal or distal

ends of the shunt• excessively low pressure• infection• migration of the distal end of the catheter resulting

in chest or abdominal pain

Surgical Procedures

• Optic Nerve Sheath Fenestration(ONSF)– Procedure in which the optic nerve just posterior to the

globe is exposed– Several slits or some other type of opening is made in

the dura and arachnoid sheaths of the nerve to allow CSF to escape, thus decompressing the nerve

– long-term effectiveness of ONSF may be fibrous scar formation between the dura and optic nerve, thus creating a barrier that protects the proximal optic nerve from the effects of increased ICP

Surgical Procedures

– Complication : infection, transient or permanent diplopia, and transient or permanent loss of vision from central retinal artery occlusion or ischemic optic neuropathy

Special Circumstances

• Pregnancy– treated similarly to nonpregnant women– no special provisions are required for delivery

unless other medical complications are present– acetazolamide can use– If a surgical procedure is required, prefer ONSF

Special Circumstances

• Fulminant Pseudotumor Cerebri– A small subgroup of patients with PTC

experience a rapid onset of symptoms and precipitous visual decline

– requires rapid and aggressive treatment– Ddx : cerebral venous sinus thrombosis