Online Module: Pseudotumor Cerebri

Pseudotumor Cerebri (PC) Also known as: Idiopathic Intracranial Hypertension Benign Intracranial Hypertension Condition (or group of conditions) characterized by the presence of elevated intracranial pressure (>20 cm H20) with no obvious underlying cause (i.e. no intracranial mass, hydrocephalus, infection, etc.). This is a diagnosis of EXCLUSION.

PC – why should you care? Almost all afflicted patients have some degree of papilledema, secondary to increased ICP. Optic disc/nerve atrophy can result in significant and permanent visual loss, even blindness. There is no correlation between risk of blindness and the intensity or duration of symptoms, number of recurrences, etc. Therefore, failure to identify these patients puts them at risk of permanent visual disability, which is preventable!

PC clinical presentation The classic patient is an overweight female of child-bearing age who presents with retro-ocular, pulsatile headache. Headache is worsened by any type of maneuver that would otherwise increase ICP (Valsalva, bending over to pick something up, etc.). Not very specific, right? Remember – this is a diagnosis of exclusion.

PC clinical presentation Other “classic” presenting symptoms: Nausea (~30%) Visual loss (~30-60%) Double vision (~30%) Less reliable, but reported symptoms also include: Neck stiffness, tinnitus (usually pulsatile), ataxia, dizziness, joint pain.

PC clinical presentation Signs – almost always related to the visual system Papilledema (approaches 100%, but can be subtle) 6th cranial nerve palsy (~10-20%) Considered a “false localizing sign,” in this case it is related to increased ICP.

PC – Visual Loss Visual loss occurs in ~50% of patients It can occur at any time during the course of PC, insidiously or suddenly, etc. There is no correlation between signs/symptoms and onset/degree of visual loss. Early changes include loss of peripheral fields and loss of color vision (change can be subtle). Central vision is affected later in the course; but progression can be quick and loss profound if undiagnosed.

PC – diagnostic criteria CSF pressure > 20 cm H20 CSF composition is normal, with possible exception of low protein (reported in >50% of cases) Signs and symptoms of elevated ICP No localizing signs, except CN VI palsy, if present Normal radiographic studies of brain with allowed exception of slit ventricles and/or empty sella.

PC – differential diagnosis Remember – Pseudotumor Cerebri is a diagnosis of exclusion; therefore, the w/u is geared towards ruling out conditions which can present with the same signs/symptoms as Pseudotumor Cerebri.

PC – differential diagnosis Intracranial mass lesions (r/o with radiography) Chiari I malformation (r/u with radiography) Infection (r/o with CSF studies) Malignant hypertension (r/o with vitals) Inflammatory/autoimmune (r/o with labs) Etc., etc., etc.

PC - evaluation Intracranial imaging – CT usually adequate for mass lesions, but MRI & MRV are preferred due to superior ability to r/o dural venous sinus thrombosis. Lumbar Puncture – only after ruling out intracranial mass lesion (or risk tonsillar herniation)! Measure opening pressure and send CSF for analysis (routine, infection, cytology, etc.)

Lumbar Puncture in PC Can be diagnostic AND therapeutic. Often, patients experience significant relief of symptoms with CSF removal. This strongly hints at the diagnosis of Pseudotumor. As many as 25% of patients may experience remission of symptoms after one LP! Goal is to bring opening pressure back under 20 cm H20.

PC - evaluation Absolutely essential in the evaluation of patients suspected to have Pseudotumor Cerebri is timely referral to Ophthalmology for full visual evaluation, and continued monitoring once established.

PC – treatment recommendations Weight loss is recommended for all patients with Pseudotumor Cerebri. For patients with headache but no visual loss: Medical management Pain meds for headache/subjective complaints Carbonic anhydrase inhibitors to decrease CSF production Lasix, steroids, etc. Intervention (for those refractory to medical management) Serial Lumbar Punctures Shunt placement (Lumbar/Ventriculo-peritoneal)

PC – treatment recommendations For patients with visual loss but no headache: Medical management and “aggressive observation” Optic Nerve Sheath Fenestration (ONSF) if vision deteriorates For patients with both visual loss and headache: If refractory to medical management, serial LPs, and/or deteriorating vision, either shunt placement and/or ONSF is advised. As general rules, ONSF is better treatment for vision; shunt is better treatment for headache.

PC – treatment recommendations PC patients with symptom onset, presentation during pregnancy – symptom relief following delivery is common. PC patients with established diagnosis who become pregnant should be referred to high-risk Ob-Gyn for guidance. Acetazolamide has associated teratogenicity.

Pseudotumor Cerebri - prognosis In general, prognosis is good. For most patients, the condition is self-limited and remission occurs within a year. As many as 25% of patients experience some degree of permanent visual loss! ~10% of patients experience recurrence of symptoms after initial remission. For a minority of patients, course is chronic.

Etiology/Pathogensis of PC Not well understood; many hypotheses. ? – Elevated central venous pressure causes decreased CSF absorption into dural venous sinuses through arachnoid granulations, leading to increased ICP ? ? – Hormonal changes ultimately result in increased CSF production ? ? – Decreased ventricular compliance ?

Summary Recognize the classic presentation of patients with PC and understand the hallmark signs of increased ICP, and especially understand what needs to happen for these patients in order to prevent permanent visual loss.