Tuesday, January 2, 2018

Brain imaging in pediatric pseudotumor cerebri syndrome

Emanuele David1, Kshitij Mankad.  Brain Imaging in Pediatric Pseudotumor Cerebri Syndrome.  J Pediatr Neurol 2015; 13(01): 049-053.

Pseudotumor cerebri syndrome (PTCS) is a clinical entity of unclear etiology characterized by raised intracranial pressure but normal cerebrospinal fluid contents and no associated anomalies evident in the brain parenchyma. Idiopathic intracranial hypertension, which is the primary (idiopathic) form of PTCS, generally affects adult obese females of childbearing age. Pediatric PTCS has been reported in association with various potential comorbidities, including chronic medical illness, infections, endocrine disorders, and ingestion and/or withdrawal of some drugs. Clinical signs and symptoms of PTCS in children are heterogeneous, but they classically include headache, papilledema, and visual disturbances (e.g., diplopia and/or vision loss). An important criterion for diagnosing PTCS involves imaging. The role of computed tomography is useful to rule out some secondary causes of elevated increased intracranial pressure (e.g., hydrocephalus, hemorrhage, mass effect); magnetic resonance imaging and magnetic resonance venography are helpful in many diagnostic challenges and in the detection of subtle intracranial anomalies (e.g., isodense tumors, meningeal infiltrations, pathologies of posterior fossa, sinus venous thrombosis). In addition, magnetic resonance imaging is able to identify some secondary signs supportive of a diagnosis of PTCS, such as flattened posterior globe/sclera, empty sella, partially empty sella/decreased pituitary height, patulous optic nerve sheath, intraocular protrusion of optic nerve head, and enhanced and increased tortuosity of the optic nerve, though these are not specific. We briefly discuss the application of imaging in the assessment of pediatric PTCS patients.

Magnetic resonance imaging examination. (A, B) Axial T2-weighted fast-spin echo images of intraocular protrusion of optic nerve head (white arrows); enlarged perioptic subarachnoid space with cerebrospinal fluid hyperintensity surrounding the optic nerves (white arrows). The optic nerve sheath widening is thought to coincide with papilledema. Partial empty sella has been shown (black asterisk) in both images.|

A 19-year-old obese woman presents to the outpatient department with a 5-month history of diffuse headaches. She also complains of transient visual obscurations and pulsatile tinnitus in both ears for the past month. Her symptoms are worse in the early morning and also aggravate with straining and coughing.

No fever, neck pain, vomiting, photophobia, altered sensorium, or seizures are noted in her history. She is single and unemployed. She is a nonsmoker and denies substance abuse. Her medical, surgical, and medication history is unremarkable. The family and social history is noncontributory…

On neurologic examination, using the measurement of meters wherein 6/6 is the equivalent of 20/20 using the customary US units of feet, the visual acuity in both eyes is reduced to 6/12. She has sixth nerve palsy on the left side. Funduscopic examination reveals bilateral optic disc swelling…

Her lumbar puncture has an opening pressure of 300 mm H20 (normal range, 70-180 mm Hg), and her CSF analysis findings are normal.

MRI of the brain with contrast reveals intraocular protrusion of the left optic nerve head with increased tortuosity of the optic nerves on axial T2-weighted imaging . No meningeal enhancement or parenchymal lesion is noted. Magnetic resonance angiography (MRA) and magnetic resonance venography (MRV) of the head are found to be normal. Goldmann perimetry reveals an enlarged blind spot…

Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri (PTC), is a disorder of diffuse increase in intracranial pressure leading to headache, diplopia, tinnitus, papilledema, and visual loss in the absence of a space-occupying lesion in the brain or other secondary causes of raised intracranial pressure. Benign intracranial hypertension is a misnomer for PTC because this disease is not benign and impairment of visual function has been reported in 25% of cases.[1,2] Blindness is a serious and permanent long-term complication of IIH…

Presumed risk factors for IIH include recent weight gain of 3.96 lb over 2 months or 20 lb over 1 year; particular medications (eg, retinoid, tetracycline, growth hormone, thyroid hormone replacement, nitrofurantoin, lithium); and systemic diseases, such as Addison disease, hypothyroidism, hypoparathyroidism, anemia, sleep apnea, systemic lupus erythematosus, Behçet syndrome, polycystic ovary syndrome, hypercoagulable states, uremia, chronic respiratory insufficiency, hypertension, multiple sclerosis, chronic kidney disease, sarcoidosis, menstrual irregularities, and diseases of cerebral venous drainage…

History typically includes an overweight young female with headache, diplopia, tinnitus, and transient/complete visual loss. Eye examination findings include positive relative afferent pupillary defect (RAPD) in some patients, diplopia, loss of visual field (typically in the inferotemporal region), decreased visual acuity, and dysfunction of color vision. Funduscopic examination reveals unilateral or often bilateral symmetric or asymmetric optic disc edema, macular edema, or exudates, choroidal folds, and retinal neovascularization. Examination of cranial nerves may show deficit (listed in decreasing frequency) of abducens, occulomotor, trochlear, olfactory, trigeminal, or facial and auditory nerves…

Patients with IIH have normal-appearing brain parenchyma and ventricles on CT scanning and MRI; the abnormalities that can be seen on MRI include posterior sclera flattening (43%-80%), distended perioptic subarachnoid space (45%-67%), postcontrast enhancement of the prelaminar optic nerve (7%-50%), empty sella (25%-80%), intraocular protrusion of the prelaminar optic nerve (3%-30%), vertical tortuosity of the orbital optic nerve (40%), tonsillar ectopia, narrowing of the Meckel cave and cavernous sinuses, meningoceles, widening of the foramen ovale, and slitlike ventricles.  MRV is performed to assess for cerebral sinus venous thrombosis; otherwise, in IIH, it may show narrowing of the transverse sinus but is not specific for IIH.

Conservative management includes weight loss and low salt intake. Studies have demonstrated significant improvement in symptoms after weight loss.[16] Medical management includes drugs that lower CSF pressure/production and prophylactic pain management. Drugs used for lowering CSF pressure include carbonic anhydrase inhibitors like acetazolamide, loop diuretics like furosemide, topiramate, indomethacin, and iron. Valproic acid and tricyclic antidepressants are use
d for prophylaxis against headache.  Surgical management includes serial lumbar punctures, CSF shunting (lumboperitoneal shunt, ventriculoperitoneal shunt), optic nerve sheath fenestration, cerebral venous stenting, and bariatric surgery for weight control.

IIH is usually a slowly progressive disease. Early diagnosis and management leads to partial recovery or slows down the worsening of symptoms. Fulminant disease carries a poor prognosis and requires urgent surgical intervention, mostly of no significant benefit.

This patient was prescribed 500 mg of acetazolamide (twice daily) along with analgesics. She was then referred to an ophthalmologist and neurosurgeon for optic nerve sheath fenestration.


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