Idiopathic intracranial hypertension is a neurological disorder that is triggered by increased intracranial pressure. Also called benign intracranial hypertension and pseudotumor cerebri, this condition does not involve the formation of tumor, though it may mimic the same symptoms.
Idiopathic intracranial hypertension (IIH) is a health condition that results from pressure exerted on the intracranial region of the brain. Though there is no tumor formation in or around the region, the symptoms are similar. The term ‘idiopathic’ means ‘existence without any underlying cause’. This is why the condition is diagnosed only in the absence of any alternative explanation for the manifestations or symptoms. Its incidence and development is determined by body weight and gender, and obesity commonly predisposes a person to this condition. There is no genetic cause for IIH yet established and it is observed in all ethnicities.
Its history dates back to 1893. Heinrich Quincke, a German physician, documented his studies as observations of ‘serous meningitis’. A compatriot, Max Nonne, coined the term ‘pseudotumor cerebri’ in 1904, for the same condition. Diagnostic criteria for this condition was defined in 1937 by Walter Dandy, a Baltimore neurosurgeon.
The intracranial pressure could result from medication such as reaction to vitamin A derivatives, tetracycline antibiotics, and oral contraceptives. The secondary causes commonly observed are delayed treatment of sleep apnea, chronic kidney diseases, and systemic lupus erythematosus. The resultant pressure within the skull is determined by the CSF (Cerebrospinal fluid), brain tissue, and blood within the skull. Any imbalance in the volume or production of any of these three cranium components results in its development.
Signs and Symptoms
This medical condition manifests in the form of:
- Severe headache
- Pulsatile tinnitus or persistent ‘buzzing’ sound in the ears
- Double vision
- Swelling of optic disc
It is diagnosed via a brain scan and lumbar puncture. Physical examination of the patient’s nervous system and inspection of the eye with an ophthalmoscope and fundus camera helps to detect cranial nerve abnormalities and facial nerve palsy. Neuroimaging, computed tomography, magnetic resonance imaging, and MR venogram are also part of the diagnostic routine. In addition, tests on cerebrospinal fluid are conducted to detect abnormal cells, and protein and glucose levels.
The treatment options aim at preventing complete visual impairment. The medication and procedures involve focus on quick symptom control. The administration of acetazolamide (Diamox) helps reduce the symptoms by inhibiting the carbonic anhydrase enzyme and reducing CSF production. However, this could trigger the onset of hypokalemia or lowered blood potassium levels, which result in muscle weakness.
Furosemide, a diuretic is also sometimes considered as the treatment option. The headache is usually controlled with analgesics and paracetamol agents. Depending on the psychosomatic triggers, antidepressants and anticonvulsants are also administered. The treatment also includes two surgical procedures ― shunting and decompression of the optic nerve sheath.
Decompression of the optic nerve sheath and fenestration is an ophthalmological process. The surgeon makes an incision in the optic nerve connective tissue to trigger CSF diversion into the orbit. Shunt surgery is a neurosurgeon supervised procedure, where a conduit is created to direct the CSF into another body cavity. While initiating the lumboperitoneal shunt in the subarachnoid space, a pressure valve is included in the lumbar spine and peritoneal cavity circuit to prevent excessive drainage. In case of an obese patient, the doctor may suggest gastric bypass surgery.