Chapter Four -
Physicians Speak Up
Dr. Benes Answers Your Questions
Dr. Susan Benes is a neuro-ophthalmologist with a practice in Columbus, Ohio. We thank her for assisting us with the following answers.
What is "empty sella" and what is its significance? What percentage of PTC patients have this "empty sella"?
"An empty sella is the small, almost dime-shaped recess in a bone right between your two eyes that is supposed to hold your pituitary gland. The pituitary gland gets squashed from increased intracranial pressure and it molds the pituitary down into a crescent shape at the bottom of that dime-shaped hole over time. I would say at least 80% of PTC patients have this empty sella. Some people with an empty sella syndrome have a lot of menstrual difficulties. I believe that the emptiness of the sella is a testimony to the fact that the extra pressure of the spinal fluid has been high for a period of time and that the sella's shape reflects the pressure problems."
Statistics that say 80% of PTC patients respond to treatment; 10% have ongoing problems. Is this accurate?
"We do not have 80% of people responding to treatment, but I think that may be because people who are sent to me are the people who did not respond to treatment. My patients have a 25% chance of getting better and off drugs completely, about a 50% chance of stabilization, and a 25% chance of progressive worsening."
PTC has been connected to another disease: systemic lupus erythematosus what is the connection?
"PTC can be a primary disorder with no other disorder along with it, or it can be connected to another disease, in which case it is called secondary PTC. Anything that can make your blood thick or your vessels thin, or can change the vein pressures in your head can give you secondary PTC. Included in this list is previous meningitis, previous hemorrhages in the head, old trauma, lupus, sarcoid, a lot of different diseases."
Has there ever been a study of weight loss and its relationship to PTC? Does it do any good to lose weight? Or are the doctors making an assumption?
"There is not a real good study about weight loss and its relationship to PTC. Each doctor has anecdotal data. In my experience, people who lose about 30% of their weight also find a remarkable difference in or an actual cessation in their PTC. I do not think this is an assumption; there is good data that obesity increases the chances of getting PTC."
What research, if any, is going on in this country concerning PTC and its effects?
"There has been research regarding Diamox, steriods, Lasix, and drugs of that sort. There has been research regarding whether Optic Nerve Sheath Decompression (ONSD) should be done and it has had a high success rate in helping vision with this disease. The real question in my mind is: should you wait until you start losing vision to do it or should it be done almost immediately? Those sorts of things ought to be studied on a nationwide study, not just in one center."
Are the "older" opinions about PTC in the medical community changing at all (specifically, it's a "benign, short-term, fat-lady's disease")?
"Idiopathic or (primary) PTC is still known to be a female predominance and an obesity predominance disease. I think it depends on where the doctors are trained and whether they think it is benign or short term. I know most ophthalmologists think it is neither benign nor short term because we take care of people who lose vision from it, but family practitioners, internists and neurologists may think that. It depends, again, where they were trained."
What is the difference between the terms 'optic nerve sheath decompression' or 'optic nerve sheath fenestration'?
"Optic nerve sheath decompression (ONSD) and optic nerve sheath fenestration (ONSF) are synonyms. Decompression means you have decompressed the nerve sheath with slits surgically and fenestration means you have decompressed it surgically with an actual window instead of slits. Truly, the word fenestration means windowing. They are not really different."
What is the "6th-nerve palsy" and how does it affect a PTC patient?
"Sixth nerve palsy is when the 6th nerve is stretched from increased intracranial pressure. It is a non-localizing sign and can cause side-by-side double vision, which is worse at a distance."
My understanding is that the arachnoid membrane is a key factor in absorbing cerebral spinal fluid. If so, is getting arachnoiditus significant?
"The arachnoid is important in absorbing spinal fluid. The arachnoid villi are the little structures that reabsorb, so if you do have arachnoiditis, it does mean that there is an inflammation of the membrane and it will be less efficient in absorbing spinal fluid. Arachnoiditis is common after meningitis, trauma or hemorrhage, and multiple spinal taps (with or without dye being introduced into the spinal fluid). It may be allergic, inflammatory or infectious."
Re: optic nerve sheath decompression- how often are visual fields increased? How often do they remain stable? How often do visual fields decrease?
"You'd need to read several articles about ONSD to find the averages of visual fields increasing and the percentages of improved vision. The subject of stability is hardly ever addressed in articles because they are short-term follow-up, for example about one or two years. Actually, I think with PTC patients we need about ten years of follow-up to answer that question properly. The percentage of people who lose visual field is fairly high. The only article which fairly addressed it long term was Jim Corbetts' article and I think he was in the 22-25% range of profound vision loss at long term level."
Dr. Corbett Talks to PTC Patients
Dr. James Corbett is a McCarty Professor and Chairman of Neurology at the Neurology Department of the University of Mississippi in Jackson, MS.
Tell us a little about yourself. How did you come to be connected with pseudotumor cerebri?
"I was born and raised in Oak Park and River Forest, suburbs of Chicago. My father, grandfather and uncle were physicians who ran an industrial medicine clinic. I went to college at Brown University after which I attended Chicago Medical School. A month-long rotation in neurosurgery at Cook County Hospital with Dr. Anthony Raimondi really consolidated my interest in neurology.
"After two years of general internal medicine at the Rhode Island Hospital, I took a residency in Neurology at Cleveland University Hospital at Case-Western Reserve. It was at this time during a three-month rotation with Dr. William Hoyt at the University of California-San Francisco that my interest in ophthalmology and neuro-ophthalmology took hold. My first experience with PTC patients and many later patients perplexed me- what I was reading in the books and journals did not conform to my own experience. I attributed this to the vagaries of individual cases and my relative inexperience.
"I spent two years in the Navy where I saw a few more PTC cases, at least one of whom went blind. I then went into private practice with Norman Schatz at Jefferson Medical School and Wills Eye Hospital. During the next four years, we developed a Pseudotumor Clinic at Wills Eye Hospital that met every Thursday morning. It became clear after seeing many patients that much of the written material was based on limited experience, follow up and a tendency to perpetuate old biases.
"In 1977, I moved to the University of Iowa where there had been a long-standing interest in PTC by Dr. A.D. Sahs, Dr. Robert Joynt and Dr. Hyndman since the late 1930's. As a result, there were many patients who had never moved from Iowa, and when we combined these patients with those seen in the previous four years at Wills Eye Hospital, we had a good data base. A group of us carefully studied and reported on 57 patients who had been followed for no less than 5 years; the longest follow up was 41 years. As a result of that study and a subsequent but similar study (of 120 patients done at the Neuro-ophthalmology Department of London's Queen Square Hospital done by James Orr and Michael Sanders), we showed that PTC was a chronic disease (this had been shown earlier in a small series of cases of Kathleen Foley from the Sloan-Kettering Hospital)."
"We showed that PTC was not always benign. Severe visual loss and legal blindness occurred in about 10% of patients and the estimates of detectable visual field loss have been shown to range between 50% and 95% depending on the type of visual field study performed. We have shown that it is overwhelmingly a woman's disease, that obesity is a feature in 90% of those women, and that in men, obesity is also a feature in 60% of the male patients.
"While the incidence of PTC in the general population is 0.9/100,000, the incidence in obese women is 19/100,000. A recent study from Canada confirms that the incidence in the general pediatric population is also 0.9/100,000. We also showed that there were risk factors for visual loss that included glaucoma and high blood pressure. The work on PTC has been the basic mainstay of clinical research through all of my career."
(Ed. note: Dr. Corbett's publication for "Focal Point 1989: Clinical Modules for Ophthalmologists- Volume #3" is an excellent piece explaining PTC. However, it is in a medical context directed toward physicians with test results, medical jargon, etc. If you can work through the medical terminology, we highly recommend you take a look at this publication. Your local library can probably request a copy.)
What type of current research is being conducted on PTC?
"Research on PTC is developing along lines that include high venous pressure, abnormalities of Vitamin A metabolism, and the contribution and treatment of obesity. A recent report from Japan shows a very low incidence of PTC in that country, which also has a very low incidence of obesity. Because this is a non-fatal disease, it requires years to study any group in enough numbers to answer even simple questions.
"As a result, research seems to be creeping along. Actually, there are some interesting ideas regarding cause and treatment.
"Dr. Selhorst at St. Louis University and I have been working in the Vitamin A hypothesis, recently joined by Dan Jacobson at the Marshfield Clinic. Dr. Friedman at Syracuse is developing an animal model of pseudotumor and has looked into a condition of idiopathic edema."
What about shunts?
"Shunts are invariably good news and bad news- no matter what type, whether one piece or two piece, or where they originate and end up. In short, they have been and always will be problematic. They are effective, as are optic nerve sheath fenestrations."
Any advice for living with this disease?
"My main advice is to recognize that a neurologist and ophthalmologist or a neuro-ophthalmologist should be seen regularly in the management of your problems. All your symptoms may not be necessarily due to PTC- for example, headache can be due to coexistent migraine and low spinal fluid pressure (post spinal tap). Many patients have this condition for a few months or a year and then the symptoms go away. Others have much more prolonged and visually complicated courses.
"Melina Mercouri from the movie, Never On Sunday used to say, 'and they all went down to the seashore' (in other words- everything came out all right in the end). Unfortunately, this is not quite true with PTC. As clinician-investigators, we are trying to have all PTC patients end up 'at the seashore'."
Dr. McGregor Answers Your Questions
Dr. John McGregor is a neurosurgeon at Ohio State University Hospitals. We thank him for past support and for assisting us with the following answers:
When a patient does not respond well to medication and surgery is indicated, which type of surgery do you think should be performed first: optic nerve sheath fenestration or a lumboperitoneal shunt, and why?
"This question speaks to an area of uncertainty in the treatment of PTC that exists in the medical community. Obviously, if one surgical procedure was far superior to the other, the decision would be a lot easier to make. Both procedures are known to provide benefit, and yet, both carry inherent risks.
"In general, it seems appropriate that the patient with PTC whose only manifestation is visual symptoms and doesn't respond to medication would probably best be served by having an optic nerve sheath fenestration. This procedure is designed to primarily protect the vision.
"On the other hand, the patient who has constitutional problems including headache, in addition to visual symptoms and who fails maximum medical therapy, should consider an LP shunt as likely to be more effective in treating both the vision problem and headache problem. Obviously, as many PTC patients know, the lumbar shunt by itself is not always effective, nor is the optic nerve sheath fenestration by itself always effective.
Some PTC patients we've heard from are getting ventricular shunts as opposed to lumboperitoneal shunts. What is the difference in the shunts and why are LP shunts more common in treating PTC?
"The goal of shunting in PTC patients is to divert the spinal fluid from the central nervous system to another part of the body, where it is more readily absorbed. For that purpose, the proximal end of the catheter is just as likely to work in the ventricle as in the lumbar space. The lumboperitoneal shunt, however, is thought to be safer than the ventriculoperitoneal shunt because the ventricular shunt must be placed into the ventricle from the surface of the skull, requiring passage of the catheter through the brain. This carries a risk, albeit small, of stroke or hemorrhage. Typically, patients with PTC have small ventricles, which makes placement of the shunt somewhat more difficult and the possibility of obstruction is somewhat more likely. LP shunts, however, have a higher incident of over-drainage than VP shunts."
Some neuro-ophthalmologists have spoken out strongly against shunts in treating PTC, citing higher failure rates and risk of infection as reasons. What has been your experience with shunts in PTC patients in your practice?
"The arguments against placing shunts in PTC patients are completely accurate. There are high failure rates and there are risks of infection. My experience has paralleled that quoted in literature, in which 50% of the patients with LP shunts will need revisions. The incidence of infection is in the range of 2-4%, and is more likely in patients requiring multiple surgeries."
Could you explain what arterial venous malformation is?
"An arterial venous malformation (AVM) is an abnormal collection of arteries and veins. In normal circulation, arteries leave the heart, become smaller until they become small arterioles, then become capillaries. The return to the heart begins as small venules, which change into veins, and return to the heart. The capillary network is so extensive that the blood pressure produced by the heart is dropped to a very low level by the time the blood returns to the venous system.
"An AVM is a collection of abnormal arteries that feed directly into the veins. These collections bypass the high resistance of the capillary bed. In other words, a shunt of blood moves away from the normal tissues and capillary beds and also from the arterial side to the venous side.
"This causes a number of changes in the blood vessel system. First, the arteries tend to enlarge to overcome the "steal" of blood through the abnormal collection- this keeps some semblance of needed flow into the capillary bed. Next, the venous system now has a direct connection to the arterial system- the pressure is transmitted from the arterial side to the venous side. This increases the pressure to the veins. The veins are not designed to handle that pressure; they have weaker walls and could rupture or bleed.
"AVMs may occur anywhere in the body. Neurosurgeons tend to deal with those primarily in the brain. Some patients have brain AVMs that cause PTC be either increased formation of CSF or decreased absorption through raised venous resistance. These patients need to have both the AVM and the PTC treated."
From a neurosurgeon's point of view, what is the most difficult aspect of treating PTC?
"The most difficult aspect of PTC is that we find ourselves treating the symptoms only and remain in the dark as to the actual cause."
Are there any new shunts or treatments for PTC on the horizon?
"There are clinical trials currently underway for radio-controlled valves that will allow programming of the rate of flow externally, like one would program someone's cardiac pacemaker. The clinical trials currently do not involve PTC patients. The device is not FDA approved at this time and is on trial in the pediatric population." (Editor's note: This type of valve has since received FDA approval.)
Pseudotumor Cerebri in Rural America
Eric L. Singman, M.D.,Ph.D., is a qualified neuro-ophthalmologist. He is one member of Eye Specialists of Lancaster, a private practice in Lancaster, PA. We thank him for his informative article.
"Why is pseudotumor cerebri (PTC) so frequently undiagnosed? Unfortunately, the modern health care situation has brought a climate where physicians are forced to spend less time with patients. They must either under-utilize services (for fear of inciting the wrath of third party payers) thereby missing diagnoses, or over-utilize services (for fear of inciting the wrath of malpractice insurers) thereby missing the forest for the trees.
"Over a year ago, I came from New York City to a relatively rural part of Pennsylvania. I'm the only full-time neuro-ophthalmologist in the county. I was trained by seeing many patients with PTC who taught me things that continue to surprise local doctors. My patients helped me understand that PTC can be caused by certain medications, foods, or worsened by head trauma. They taught me to ask whether the patient snores or smokes. I've realized that PTC can present without headaches, without vision disturbances, without an elevated opening pressure on lumbar puncture, or despite the fact that the patient was not overweight.
"The following vignettes are drawn from the sixty or so patients I have diagnosed in the past year. It is significant that the incidence of PTC in our county rises 5 to 10 times above the expected 1 or 2/100,000 population. As a a neuro-ophthalmologist, I was specifically trained to bridge the disciplines of neurology, ophthalmology, and internal medicine. I am sometimes frustrated or even angry at how PTC patients were treated prior to receiving their diagnosis. I have now turned those energies into sincere efforts to ensure that these patients will never be made to feel badly again.
"My first patient was a relatively classic case. She was in her 50's and used prednisone for arthritis. She had gained a great deal of weight and presented with visual disturbances and optic nerve head edema. A lumbar puncture confirmed the diagnosis; she was started on Diamox, which served as a temporizing measure to reduce the intracranial pressure (ICP). But a new set of problems arose. She needed the prednisone and was having great difficulty losing weight. Would she be on Diamox for the rest of her life? The patient moved away before we could suggest an optic nerve sheath fenestration. Previous patients in similar circumstances would have been offered only a LP or VP shunt. Considering the failure rate of these procedures comes close to 80% within a decade of surgery, I was anxious to ensure that this patient had a third surgical alternative.
"Another of my first PTC patients was a woman receiving steroids (for lupus), with a previously known history of optic nerve head drusen. These are concretions buried under the optic nerve that cause pseudo-papilledema, or the appearance of papilledema despite normal pressures in the brain. Because of the drusen, she had not received a diagnosis of true papilledema and suffered headaches for years. A lumbar puncture confirmed the presence of PTC. This patient is doing well on Diamox and has been headache-free for the first time this decade.
"Another case is a 19 year old girl who had tried committing suicide at least 10 times by hitting her head against a wall. She had chronic headaches but no papilledema. Rather, the optic nerves showed no spontaneous venous pulsations; this was her only evidence of increased intracranial pressure. Her opening pressure on lumbar puncture was well over 300. She said Diamox did not help, but she was known to be noncompliant with her other medications. When we ensured that she did use Diamox, the spontaneous venous pulsations returned. The absence of this subtle finding was the only firm clinical clue of increased intracranial pressure. One wonders how much the PTC played a role in her mental illness. Why should pressure on the brain only cause headaches and not also behavioral changes?
"Some of my male patients with PTC are most interesting. The first is a 300# man with borderline sleep apnea. His headaches were causing him to be depressed and his opening pressure was only 200. I was advised by other clinicians to consider a diagnosis other than PTC because opening pressures of up to 250 can be acceptable as normal in obese individuals. However, I thought it best to offer Diamox, a situation known as a therapeutic trial. His headaches resolved completely within 48 hours using a low dose (250 mg by mouth three times a day).
"My second male patient is a young healthy man who is an award-winning marksman in excellent physical condition. Many years ago, he was treated with a great number of antibiotics, probably including tetracyclines, during an unusual inflammatory illness believed to be infectious. He complained of a visual disturbance in only one eye. His vision was 20/20. He had optic nerve head swelling in the affected eye; his opening pressure was 270. I expect that fellow will opt for an optic nerve sheath fenestration to protect the nerve and cure his ailment, because sulfa drugs sicken him severely.
"Other interesting patients have come through our door. One was a thin woman who binged on licorice; licorice contains glycericic acid, known to cause PTC. Another woman was going to have bilateral optic nerve sheath fenestrations and stomach stapling as a way of treating the PTC; her condition resolved completely when nasal continuous positive airway pressure (CPAP) was started to treat her sleep apnea, a lesser known cause of PTC! I ask all my patients if they smoke (a terrific promulgator of sinusitis), snore (indicative of resistance to smooth breathing) are groggy all day long (because sleep is no longer refreshing) or have headaches upon awakening, a hallmark of sleep apnea and other sleep disturbances.
"Classic PTC seems to represent only the majority of cases. Perhaps this might change. Thomas Spoor, M.D., in Michigan, a brilliant man and a pioneer in PTC, believes that some 20% of PTC cases might have normal optic nerve heads. I think we are just seeing the tip of the iceberg, at least in my little piece of rural America. Dr. Spoor and I agree about putting an end to the often prejudicial treatment PTC patients suffer at the hands of health care providers. I suspect that patients are treated as "complainers" or second-class patients because:
(1. patients are often women,
(2. have complaints that might be difficult to understand by physicians insufficiently familiar with PTC, and
(3. often do not look like the starvelings on the cover of many fashion magazines.