Intracranial Hypertension Flashcards
Idiopathic Intracranial Hypertension
Idiopathic intracranial hypertension (also known as pseudotumour cerebri and formerly benign intracranial hypertension) is a condition classically seen in young, overweight females.
Idiopathic Intracranial Hypertension - Features
Features headache blurred vision papilloedema (usually present) enlarged blind spot sixth nerve palsy may be present
Idiopathic Intracranial HTN - Risk Factors
Risk factors obesity female sex pregnancy drugs*: oral contraceptive pill, steroids, tetracycline, vitamin A, lithium
*if intracranial hypertension is thought to occur secondary to a known causes (e.g. Medication) then it is of course not idiopathic
Idiopathic Intracranial HTN - Formal Diagnosis
Formal diagnosis (by Modified Dandy criteria), requires CSF opening pressure greater than 25 cmH2O and normal brain imaging. Imaging is required to exclude venous sinus thrombosis, which could result in the same signs and symptoms and is also more common in women on the oral contraceptive pill. The gold standard imaging for this would be MRI with contrast of the head and orbits and MR venogram.
Drug Causes of Idiopathic Intracranial HTN
Associated medications include, but are not limited to: tetracycline antibiotics isotretinoin contraceptives steroids levothyroxine lithium cimetidine
Pt with ‘known’ idiopathic intracranial HTN: Example Question
A 27 year-old woman attends the neurology clinic complaining of headache and visual disturbance. She has recently immigrated from Ghana. Her symptoms began approximately one month ago, shortly after the birth of her first child. She experiences dull frontal headache which is worst in the mornings and on coughing or straining, as well as transient episodes of ‘darkening’ of her vision. She saw a doctor in Ghana and was diagnosed with idiopathic intracranial hypertension. She is taking acetazolamide 250mg BD and no other medication.
On examination the visual fields are markedly constricted and the right blind spot is enlarged. Fundoscopy shows bilateral papilloedema worse on the right. The remainder of the neurological examination is unremarkable. BMI is 18 kg/m².
Plain computed tomography of the brain is normal.
Incidentally as she is leaving the clinic she mentions that she has also been experiencing pins and needles in the hands and feet.
What is the best course of action?
Increase dose of acetazolamide Request nerve conduction studies Organise for therapeutic lumbar puncture Refer to neurosurgeons for consideration of ventriculo-peritoneal shunting > Request CT venography
The history of headache suggestive of raised intracranial pressure associated with transient visual obscurations, as well as the examination findings, are all compatible with idiopathic intracranial hypertension (IIH). However, the onset of symptoms in the puerperium, in a slim patient with no other risk factors for IIH, raises the suspicion that this may actually be a cerebral venous sinus thrombosis. All patients with IIH should have imaging of the venous system with CT or MR to exclude a thrombus which can be more appropriately treated with anticoagulation.
Therapeutic lumbar puncture can ease the headache of IIH but is a short-term measure. Ventriculo-peritoneal shunting can be used where medical management has failed.
There is no role for nerve conduction studies in this patient. Paraesthesia are a common side effect of acetazolamide, and this patient is unlikely to tolerate an increase in the dose.
Idiopathic Intracranial HTN - Mx: Example Question
A 32 year old female is seen in neurology clinic due to a 4 month history of headaches. She described having headaches most days on waking up, which were throbbing in nature. She found that they eased off after mobilising, and that coughing made them worse. She reported a couple of episodes of blurred vision on waking, but no nausea or vomiting. Her general practitioner arranged for an outpatient magnetic resonance head scan which was normal. Her body mass index (BMI) had been 27 kg/m², but on advice from her general practitioner she had lost weight, and her BMI was now 23 kg/m². She was not on any regular medications, other than paracetamol and ibuprofen which she had been using regularly for her headaches.
There was no focal neurological deficit on examination, and her visual acuity was normal. On fundoscopy there was a mild degree of papilloedema. Blood pressure was 125/82mmHg. Blood tests were unremarkable.
What is the most appropriate next step in management?
Lumbar-peritoneal shunt Optic nerve fenestration Cessation of paracetamol and ibuprofen > Acetazolamide Sumatriptan
The postural nature of this patient’s headaches, and the fact that they are exacerbated by coughing are suggestive of raised intracranial pressure. In a young woman with a normal magnetic resonance scan, this is suggestive of idiopathic intracranial hypertension.
In overweight patients, the initial management strategy is weight loss, which may be enough to relieve symptoms. This patient has already lost weight and has a normal body mass index, but her headaches persist, so additional measures are required. Cessation of any causative agents would also be important (e.g. tetracyclines, retinoids, lithium).
Acetazolamide is useful in controlling mild disease that is resistant to the conservative measures mentioned above. Repeated lumbar puncture may also be used to lower intracranial pressure. In acute disease corticosteroids are sometimes beneficial. If there is significant visual loss despite medical therapy surgical interventions such as optic nerve sheath fenestration or lumbar-peritoneal shunt insertion may be necessary.
Analgesia-induced headache and migraine are important causes of recurrent headache, but would not cause the postural association seen in this case, so cessation of analgesic agents and commencement of sumatriptan are not appropriate treatments.
Idiopathic Intracranial HTN - Mx
In overweight patients, the initial management strategy is weight loss, which may be enough to relieve symptoms.
Cessation of any causative agents would also be important (e.g. tetracyclines, retinoids, lithium).
Acetazolamide is useful in controlling mild disease that is resistant to the conservative measures mentioned above. Repeated lumbar puncture may also be used to lower intracranial pressure. In acute disease corticosteroids are sometimes beneficial. If there is significant visual loss despite medical therapy surgical interventions such as optic nerve sheath fenestration or lumbar-peritoneal shunt insertion may be necessary.
Idiopathic Intracranial HTN: Mx
- Weight loss
- Diuretics eg Acetazolamide
- Topiramate also used (has added benefit of weight loss)
- Repeated LP
- Surgery > optic nerve sheath decompression and fenestration may be needed to prevent damage to optic nerve
- A lumboperitoneal or ventriculoperitoneal shunt may also be performed to reduce intracranial pressure
