Draft admission prescription: suspected/confirmed idiopathic intracranial hypertension (adult)

Use only after in-person assessment by the admitting neurology/ophthalmology team. Urgently escalate if there is rapidly worsening vision, marked visual-field loss, severe papilledema, or altered consciousness.

1. Admit and monitoring

1. Admit under Neurology.
2. Neuro-ophthalmology/Ophthalmology review urgently, same day. Document:
   • Visual acuity, pupils/RAPD, colour vision
   • Dilated fundus examination and papilledema grade
   • Automated visual fields, if feasible
   • OCT retinal nerve fibre layer, if available
   • Ocular motility, specifically sixth-nerve palsy
3. Neurological observations, GCS, pupils, headache score and visual symptoms 4-hourly.
4. Record BP, pulse, temperature, SpO₂ 4-hourly.
5. Daily weight; strict input/output chart.
6. Fall precautions if visual impairment/dizziness.

2. Investigations - urgent

1. MRI brain with contrast plus MR venography urgently, before lumbar puncture where possible, to exclude mass lesion, hydrocephalus, and cerebral venous sinus thrombosis.
2. If MRI/MRV unavailable or contraindicated: CT brain followed by CT venography as directed by Neurology/Radiology.
3. After safe neuroimaging: lumbar puncture in lateral decubitus position:
   • Document opening pressure with legs extended and patient relaxed.
   • Send CSF for cell count/differential, protein, glucose, Gram stain/culture as clinically indicated.
   • Do not diagnose IIH from pressure alone. CSF composition must be normal and mimics excluded.
4. Blood tests:
   • CBC with platelets
   • Urea, creatinine, electrolytes including bicarbonate
   • LFT
   • Blood glucose
   • PT/INR, aPTT if LP planned or anticoagulant use suspected
   • Serum pregnancy test in patients with pregnancy potential, before drugs/imaging
   • Consider ESR/CRP, thyroid testing, iron studies, and other secondary-cause workup based on history.

3. Medications

• Tab acetazolamide 250 mg orally twice daily, start after baseline renal function/electrolytes are reviewed and contraindications are excluded.
• Titrate by 250 to 500 mg/day every 2 to 3 days according to visual status, symptoms, tolerance, renal function and specialist advice.
• Usual inpatient target is individualized. Do not automatically escalate to high doses.
• Monitor electrolytes, bicarbonate and renal function within 48-72 hours after initiation or dose escalation, then as clinically indicated.
• Withhold and discuss with Neurology if significant metabolic acidosis, hypokalaemia, acute kidney injury, sulfonamide hypersensitivity, or renal calculi symptoms.

• Tab paracetamol 500-1000 mg orally every 6-8 hours when required, maximum 3 g/day unless local policy permits otherwise and hepatic function is normal.
• Avoid opioid analgesics where possible. Avoid medication-overuse headache from frequent rescue analgesics.

• Tab/IV ondansetron 4 mg every 8 hours when required, or local formulary alternative.
• Check QT-risk factors before repeated ondansetron use.

• No routine corticosteroids for IIH.
• No routine mannitol or hypertonic saline for uncomplicated IIH.
• No routine serial lumbar punctures as definitive therapy. A therapeutic LP may be used only as a short bridge under specialist direction, especially while arranging definitive treatment for threatened vision.

• Do not start routinely on the admission order. Consider only with Neurology for a migraine phenotype and/or weight-management benefit, after reviewing cognitive adverse effects, renal stone risk, contraception interactions, and pregnancy risk. It should not be used in pregnancy.

4. Non-drug orders

1. Dietitian/weight-management referral. Initiate a calorie-controlled, low-sodium diet if appropriate. Sustained weight reduction is the disease-modifying treatment in typical IIH.
2. Review possible precipitating/secondary causes and medications, including tetracyclines, vitamin-A derivatives/retinoids, growth hormone, lithium, and recent corticosteroid withdrawal. Do not stop prescribed drugs without the responsible specialist.
3. Encourage mobilization as tolerated. Give VTE prophylaxis only according to institutional risk assessment and after considering planned LP/procedures.

5. Escalation orders

1. Immediate Neurology + Neuro-ophthalmology review for any new/worsening visual obscurations, visual-field deterioration, reduced acuity, RAPD, worsening papilledema, or new cranial nerve palsy.
2. If visual function is deteriorating despite medical measures, obtain urgent Neurosurgery consultation for vision-saving CSF diversion or optic nerve sheath fenestration, according to local expertise.
3. If cerebral venous sinus thrombosis is identified, treat as CVST rather than IIH.

Important prescribing checks

• Confirm pregnancy status and discuss fetal risk before acetazolamide.
• Document counselling for acetazolamide adverse effects: paraesthesia, fatigue, dysgeusia, nausea/diarrhoea, tinnitus, mood symptoms, renal stones, electrolyte disturbance and metabolic acidosis.
• IIH diagnostic criteria require papilledema or appropriate alternative criteria, normal neurological examination except possible sixth-nerve palsy, normal brain imaging with venous thrombosis excluded, normal CSF constituents, and elevated LP opening pressure. Bradley and Daroff's Neurology in Clinical Practice, p. 2459.
• Acetazolamide is commonly started at 250-500 mg twice daily, with dose titration and electrolyte monitoring, as described in the IIH consensus guideline.
• A recent 2025 systematic review compared topiramate and acetazolamide, but this does not remove the need for specialist-directed selection, especially in patients with pregnancy potential.

• Mannitol 20% IV 0.25-1 g/kg stat over 15-30 minutes
• This equals 1.25-5 mL/kg of 20% mannitol
• A commonly used initial bolus is 0.5 g/kg = 2.5 mL/kg of 20% solution IV over 15-30 min.

• 0.5 g/kg = 35 g
• 20% mannitol contains 20 g/100 mL
• Give 175 mL IV over 15-30 minutes.

Inj Mannitol 20%, 0.5 g/kg IV stat over 15-30 min, only after senior Neurology/Neurosurgery review. Monitor BP, urine output, serum sodium, potassium, bicarbonate, creatinine and serum osmolality. Avoid repeat dose without reassessment.