150 Pseudotumor cerebri

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Pseudotumor cerebriYoumans,Neurological surgery 6th editionChapter 150Neil R Miller07/03/59

Terminologypseudotumor 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 imagingnormal cerebrospinal fluid (CSF) contentpapilledema occurring in most cases (but not all)young, obese women without any clear explanation

Epidemiologyinfants, children, and young adults90% of cases, is typically a disorder of obese females of childbearing age

Symptoms and SignsAsymptomatic and discovered during a routine ophthalmic examination when papilledema is foundHeadache(90%)generally different from previous headaches and is severebifrontal or generalized, pressure-like, and often associated with neck painmigrainous features, including unilateral pain, nausea, vomiting, photophobia, and phonophobiabrain 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 SignsTransient obscurations of vision (TOVs)(70%)partial or completeunilateral or bilateralfew secondsprecipitated by a change in posture (e.g., bending over, arising from a stooped position) or rolling the eyesindicate the presence of optic disc swellingnot a sign of a poor prognosisVisual lossenlarged dark spot in the temporal visual field

Symptoms and SignsDiplopia(40%)horizontal diplopiaresults from unilateral or bilateral abducens nerve paresisnonlocalizing feature of increased ICPPulsatile tinnitus : uncommon whooshing sound, hearing a heartbeat in the head, or a high-pitched noisereflect flow disturbances within the cerebral venous systemunilateral or bilateraloften more prominent at night or in quiet surroundings

Symptoms and SignsPapilledemadiagnostic hallmarkalmost always bilateral and symmetrical but it may be asymmetric or, occasionally, unilateralcrucial in determining the appropriate management of any patient with papilledema

Frisen Scale

Diagnosisno intracranial or spinal massno evidence of hydrocephalusMRI is recommenddocumented increased ICPNormal lumbar CSF pressure in both obese and nonobese adult : 20-25 cmH2OPrepupertal : greater than 20 cmH2O is abnormalmonitoringnormal CSF contents glucose and protein concentration, presence of cells, cytology, and atypical infections (e.g., syphilis, cryptococcus, fungus)

Secondary Pseudotumor cerebri

Secondary Pseudotumor cerebri

ComplicationPermanent visual lossCSF pressure remained elevated

PathophysiologyUnclear mechanism,both IIH or secondary PTCPlasma levels of ghrelina hormone that appears to be involved in the regulation of body weightfound no difference between obese patients with and without evidence of IIH

MonitoringVisual field defectSimilar to that occurring in patients with chronic open-angle glaucomaprogressive visual field constriction, color vision loss, and finally, loss of central visionMost visual deficits associated with papilledema are reversible if ICP is lowered before severe visual loss or optic nerve ischemia developsOphthalmologist

Monitoring

MonitoringAt disease onset, some patients require an evaluation every 1 to 2 weeks until a pattern of progression or stability is establishedOther patients can be examined every 1 to 3 months without fear that they will lose vision in the interimPatients with stable vision and mild or moderate papilledema may need to be examined only every 4 to 12 months

TreatmentNeurologist, ophthalmologist, primary care physician, and neurosurgeonPresence and severity of symptoms such as headacheDegree of visual loss at initial examinationRate of progression of visual lossPresence 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 ObesityWeight loss, restrict food and exerciseDecreasing food intake while increasing water consumption and sodium restrictionWhen weight loss efforts fail, bariatric surgery may be consideredWeight reduction should not be used as the only treatment in patients with PTC

Medical TreatmentMost appropriate when the primary problem is headache in the setting of good visual functionCarbonic anhydrase inhibitorsdecrease the production of CSF and thereby result in decreased sodium ion transport across the choroidal epitheliummild diuretic effectdose of 1 g/day given in divided doses of either 250 mg four times a day or 500-mg Sequels twice a daymaximum dose 4g/dayside effect : paresthesias of the extremities, lethargy, and altered taste sensation

Medical TreatmentRepeated Lumbar Puncturehigh-volume LP, with removal of 20 mL of CSF or morelow-pressure headaches may develop after this procedure in patients in whom this is donePressure into the normal range (target closing pressure range of 14 to 18 cm H2O)

Surgical ProceduresSevere optic neuropathy or when other forms of treatment have failed to prevent visual lossIt is not recommended for the treatment of headaches alone

Surgical ProceduresCerebrospinal Fluid Diversion ProceduresIn the past : lumboperitoneal shuntOften malfunction and infectionNow : stereotactic devices for place shuntComplicationspontaneous obstruction of the proximal or distal ends of the shuntexcessively low pressureinfectionmigration of the distal end of the catheter resulting in chest or abdominal pain

Surgical ProceduresOptic Nerve Sheath Fenestration(ONSF)Procedure in which the optic nerve just posterior to the globe is exposedSeveral 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 nervelong-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 ProceduresComplication : infection, transient or permanent diplopia, and transient or permanent loss of vision from central retinal artery occlusion or ischemic optic neuropathy

Special CircumstancesPregnancytreated similarly to nonpregnant womenno special provisions are required for delivery unless other medical complications are presentacetazolamide can useIf a surgical procedure is required, prefer ONSF

Special CircumstancesFulminant Pseudotumor CerebriA small subgroup of patients with PTC experience a rapid onset of symptoms and precipitous visual declinerequires rapid and aggressive treatmentDdx : cerebral venous sinus thrombosis