||Andrew G. Lee, MD, Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, TX; Professor of Ophthalmology, Weill Cornell Medicine; Angela Huang, Baylor College of Medicine Class of 2021
||So today we are going to be talking about IIH: idiopathic intracranial hypertension. It is defined by criteria which we call the modified Dandy criteria. They have to be modified because Dr. Dandy worked at the Johns Hopkins hospital in the days before imaging studies, so we've had to account for the improvements in imaging studies. The only thing you've got to remember about intracranial hypertension is that it's all about increased intracranial pressure. You can have only symptoms of increased intracranial pressure, and those symptoms are headache, transient visual obscurations lasting seconds at time, pulse synchronous tinnitus, and blurry vision. You can also have also double vision from a non-localizing finding of increased intracranial pressure, a sixth nerve palsy. Rarely patients have a seventh nerve palsy, but your symptoms must be confined to increased ICP. Symptoms are what the patient says. You can only have signs, what we see, of increased intracranial pressure, and those signs are visual loss, big blind spot on the visual field from the papilledema, or a sixth nerve palsy as a non-localizing sign of increased intracranial pressure, and papilledema. Rarely you can have a seventh, but really you are not allowed to have anything else as a sign, only signs of increased intracranial pressure. You have to have scans and the preferred scan of course is MRI with contrast plus an MR venogram to make sure that it's not venous sinus thrombosis. And we can only have radiographic findings on the MRI and MRV of increased intracranial pressure. Those radiographic signs include flattening of the globe, and fluid in the optic nerve sheath, an empty sella, and stenosis but not thrombosis of the junction of the transverse and sigmoid venous sinus. If we have signs radiographically of increased intracranial pressure, that supports the diagnosis. And then finally, if the MRI/MRV is negative, we will generally do a spinal tap and the only thing you are allowed to have on the spinal tap is increased intracranial pressure on opening pressure. You cannot have any abnormalities, sensory or spinal fluid protein, glucose, white count. It can't be anything wrong with the CSF constituents. The only thing you are allowed is increased ICP. And so, in summary, to make the diagnosis of idiopathic intracranial hypertension, you must follow the modified Dandy criteria, and it is all about ICP. You can have only symptoms of increased ICP, signs of increased ICP, radiographic signs of increased ICP, and your spinal tap better show increased ICP but nothing else, and if you done that, then then they have pseudotumor cerebri. Most of the patients, 95% of the cases, are obese young females. Weight loss is the best long-term treatment of the disorder. And a recent randomized controlled clinical trial which are we are not going to cover today: the idiopathic intracranial hypertension trial showed that acetazolamide and weight loss are the best first line treatments, and if patients fail, are intolerant of, or noncompliant with maximum medical therapy, weight loss, and the acetazolamide, and if they have progressive vision loss or intractable headache, then you can have surgery. Our two surgical choices are a shunting procedure, CSF diversion procedure. Our choice normally is stereotactically placed ventriculoperitoneal shunt with a programmable valve, but you could use an LP shunt. Or if it is vision loss that is the primary driver for surgery, optic nerve sheath fenestration. Recently, stenting of the stenotic segment in the MR venogram has been proposed but it has yet to be proven in a randomized control clinical manner. However, if there is a pressure gradient and they are not a good survival candidate or if they have progression despite maximum treatment, you could do a stent across that venous sinus. Stay tuned to this channel for whether that is true or not. So hope you know a little more about idiopathic intracranial hypertension.