Neurosurgery and CFS
Many questions still remain

An anonymous letter to individuals considering the Chiari surgery. The author of this letter has had CFS and neurally mediated hypotension since 1991. She had neurosurgery in March 1999. A complication of that procedure will be repaired through further surgery this spring.

Dear friends:
At 13 months post-op, I have not forgotten the sky-high hopes that preceded my neurosurgery for a Chiari-like malformation. Unexpected complications have made me more aware of the complexity and incomplete information about Chiari malformations and chronic fatigue syndrome (CFS).  Although I am hopeful about the long-term outcome of decompression surgery, I'd like to point out some of the unknowns, so that others who consider this option can base their decisions not only on hopeful thinking but also on their willingness to accept the unanswered questions and the potential for unforeseen risks.

Disagreement over diagnosis
Although traditional criteria for the diagnosis of Chiari have been used for many years, there has recently been debate about the expansion of this label.

Each of us has an opening at the base of the skull where the spinal cord enters and joins the brain. In individuals with Chiari I malformations, the cerebellar tonsils, two appendages of the brain at the base of the cerebellum, bulge out so that they extend 5 mm below the opening. This degree of herniation of the cerebellar tonsils can be seen on a MRI and is the standard for the diagnosis of a Chiari I malformation¹.

The reason the cerebellar tonsils herniate is that there isn't enough room in the base of the skull for the hindbrain: the cerebellum and brainstem. In addition, the cerebellum is sometimes just too long.

In a controversial move, some neurosurgeons have expanded the "Chiari" label, diagnosing Chiari malformations when there is less than 5 mm of herniation of the cerebellar tonsils.

Although these patients' cerebellar tonsils are not herniated as much as those of classic Chiari I patients, their symptoms mimic those of Chiari I malformations, their neurological exams show subtle abnormalities and their MRIs and other neurological tests suggest crowding, reduced cerebral spinal fluid flow and/or compression of the spinal cord.

Conservative neurosurgeons question whether the term "Chiari" truly applies to these patients and are concerned about the relaxation of criteria for surgery. The controversy is heightened by the coexisting diagnoses that many of these patients have: CFS, fibromyalgia (FM) and neurally mediated hypotension.

The right testing is necessary
Because of the controversy about the diagnosis of Chiari malformations, it's important to have the right tests, such as high-quality MRIs. MRI films should be evaluated by a neurologist or neurosurgeon with experience in the treatment of Chiari malformations. It is not uncommon for radiologists reading MRIs to miss the diagnosis.

It's important that the MRI used to diagnose or rule out a Chiari malformation include an adequate number of clear images of the base of the skull and its opening through which the spinal cord meets the brain. It's also a good idea to have an MRI of the entire spine to rule out other problems that could impact a Chiari malformation or cause similar symptoms.

For example, some neurosurgeons believe that untreated cervical spinal stenosis-narrowing of the spine in the neck-can be a more important cause of symptoms than a mild Chiari malfor-mation. If cervical stenosis is the more important problem, but isn't recognized to be contributing, then decompression surgery for a mild Chiari malformation could make symptoms worse.

A cine-MRI, which evaluates the flow of cerebral spinal fluid in coordination with the heartbeat, is valued by some neurosurgeons in diagnosis, especially when classic Chiari criteria are not met.  

Who will benefit from surgery?
How abnormal must your MRI, neurological exam and neurological tests be for you to qualify as someone who would probably be helped by decompression surgery?

Neurologists and neurosurgeons with an interest in the expansion of the Chiari label might consider you a candidate for neurosurgery in the absence of tonsillar herniation if they feel you have severe crowding at the base of the skull or stenosis of the cervical spine. However, surgery for patients who do not meet the criteria for Chiari I is considered very experimental.

Without published research on this subject, physicians cannot predict which patients will benefit from this experimental therapy and how much it will help. Because of this uncertainty, expect most neurologists and neurosurgeons to be quite conservative in their recommendations. If they can't diagnose you with Chiari I or severe cervical spinal stenosis, most will suggest that you not pursue surgery at this time. 

It is a difficult judgment call to decide how much improvement is worth the risk of major surgery. There is also the risk that if CFS patients don't get better following decompression surgery, physicians may blame their continued symptoms on psychosocial factors and cease searching for medical explanations for their disability.

Which surgical method is best?
Although a "standard" decompression surgery has been performed since the 1950s, many neurosurgeons have their own preferences regarding the details. Small differences in method exist for each significant step in the surgery. Unfortunately, there is no published data on these differences to help patients choose the method and surgeon they are most comfortable with.

A distinction commonly discussed is the size of the craniectomy performed by different surgeons-how much skull is removed to allow greater space for the brain. There is much discussion among patients about whether a large craniectomy (supra-sinus craniectomy) is best.

Initially, I assumed that removing more skull would create more space, reducing the chance that further surgery would be needed. However, I've since heard of several patients whose craniectomies were too large. When too much bone is removed, a well-recognized complication is that the cerebellum loses some of its structural support, and slides down through the bony opening, causing intense discomfort and increasing other symptoms.

Another disparity in neurosurgical methods is the removal of a section of the dura, the outer membrane covering the brain. After the crani-ectomy, neurosurgeons commonly open the dura, remove a section, and replace it with a dural patch to create more room for the hindbrain.

The neurosurgeon providing my follow-up care believes the dura should never be removed because this natural lining is stronger and more durable than the materials used in dural patches. One complication that can result from the weakness of a dural patch is a pseudomeningocele (PSM)-a fluid-filled sac caused by a leak in the patch or a patch that stretches out.

A third disparity in surgical methods is that some neurosurgeons place a molded metal plate over the hole created by the craniectomy. This preserves the normal shape of the skull. Which surgical method is best? It is too soon to tell. Only quality studies, with well-defined patient groups and outcome measures, will allow neurosurgeons to sort out the pros and cons of their differing methods.

Prepare for the unexpected
Individuals considering surgery should realize that it might not be as straightforward as correcting one malformation. If a patient has Chiari and cervical spine stenosis, these conditions may be treated with two separate surgeries. Hopefully, a Chiari patient can be helped with just one decompression, but additional operations are sometimes needed.

Even follow-up treatment for some complications falls into a gray area. Neurosurgeons seem to disagree about whether the PSM is cause for concern. Some patients may develop PSMs and still feel much improved. Others (like me) may have major pain at their neurosurgical site and worsening of their neurological symptoms.

In my case, although my dural patch is stretched out and filled with cerebral spinal fluid, my MRIs were read as normal by a radiologist and neurosurgeon. My neurologist, upon viewing my films at eight or nine months post-op, thought he saw a PSM and confirmed the diagnosis with a different neurosurgeon (who had seen PSMs cause pain in other patients and was more sensitive to the issue). Now I have an explanation and a repair of the PSM may at least relieve the pain at my surgery site.

PWCs may also require special care to prevent complications resulting from other conditions. For example, if you have Ehlers Danlos Syndrome (which causes the connective tissues to be extra "stretchy") you might need an altered surgical method to add to the strength of the stitches. Be sure to discuss coexisting conditions with your neurosurgeon well in advance.

Make an informed decision
It can be emotionally difficult to face this procedure. If you do not see rapid, significant improvement after, the disappointment can be a heavy burden to bear, especially when friends and extended family expect that you've been cured and can return to a "normal life."

Opting for Chiari surgery, as with many CFS treatments, means accepting gray areas and unanswered questions. Your "informed consent" will be a work in progress, as more is learned about the role of Chiari and other neurological disorders in CFS.

My personal choice was to accept the risks. My physicians shared all of the information they had at the time and I spent many hours reading medical articles on Chiari. Even so, I am surprised by the things I have learned about neurosurgeons' approach to Chiari surgery, and the effect it has had on my life.

I encourage patients to ask many questions before choosing surgery, confirm that they've exhausted their medical options for treating CFS and coexisting conditions, have adequate diagnostic procedures and find a surgeon whose methods they are comfortable with before they make their decision.

Wishing you the best of health,
A fellow PWC

References:
1.  Milhorat H. Chiari I Malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery. 1999; 44(5):1005-1015. n

20/20 Brings Neurosurgery into Spotlight
A segment on ABC’s "20/20" in March explored the controversial suggestion that some CFS and fibromyalgia patients might actually have a central nervous system abnormality that can be treated with surgery. The show, which talked about both Chiari malformations and cervical stenosis, received a huge response.

Visitors to ABC’s web site were invited to e-mail questions for an on-line chat with neurosurgeon Dr. Daniel Heffez following the broadcast. More than 6,000 questions were received, a new record for the site.

PWCs should keep in mind that Chairi malformations and cervical stenosis are relatively rare.  One good resource for finding neurosurgeons with extensive experience in diagnosing and treating these conditions is the World Arnold Chairi Malformation Association’s web site and Internet discussion list ( http://www.pressenter.com/~wacma/). The CFIDS Association’s web site also includes Chiari news and resources--see the Medical Issues section of www.cfids.org.