The purpose of this short report is to review the medical literature concerning what has been researched on this topic. Considering any neurosurgical procedure is certainly one of the most significant issues of anyone’s life.
A Chiari I malformation results from what is termed a “developmentally small posterior cranial fossa.” The posterior cranial fossa is the back part of the skull and is the part of skull where those parts of the brain called the cerebellum and the brainstem live. Because it is too small part of the cerebellum, called the cerebellar tonsils, don’t have enough room in the posterior fossa and have to squeeze out through the opening through which the spinal cord enters. That opening is called the foramen magnum, which derives from Latin and means, “large opening.” This is the opening in the skull through which the spinal cord enters to join the brain. When the cerebellar tonsils squeeze out they may compress the spinal cord. By definition, a Chiari I malformation requires that the cerebellar tonsils squeeze out of the foramen magnum by > 5 millimeters. The normal position of the cerebellar tonsil is one to three millimeters above the foramen magnum. However, there is still some confusion regarding this definition as the results from a large study of 364 patients without FMS but with Chiari I malformation have shown that a protrusion of less than 5 millimeters may not exclude the diagnosis.
The possibility of a relationship between Chiari malformation and FMS was originally published as an abstract in 1997 by Dr. Alarcon and his colleagues. Unfortunately, this work was incorrectly described by an independent reviewer when rewritten in the proceedings of a symposium that was presented following the 1998 Annual Scientific Meeting of the American College of Rheumatology (ACR). The errors were brought to attention through a letter to the editor of the scientific journal in which they appeared by Drs. Bradley and Alarcon, the people who did the original research. However, the mistakes are still being quoted today. The most commonly quoted error was that spinal cerebrospinal fluid levels of substance P were substantially higher (over double) in FMS patients with Chiari malformation than in those without Chiari while in reality there was no significant difference.
This has resulted in thinking that a Chiari malformation can both block the flow of the body’s inhibiting chemical mediators down into the spinal cord and also trap substance P in the spinal cord. If you recall from reading the short report on the “Pain is in the Brain in FMS” you will remember that substance P is a very important pain molecule. By trapping substance P in the spinal cord the thinking was that it would continually irritate the pain nerves and increase the pain levels of patients with FMS. Drs. Alarcon and Bradley directly addressed this in their letter to the editor as a statement they never publicly or privately advocated.
They also addressed a statement in the review of their work which stated that “at least 30 persons with FMS-like symptoms and clinical evidence of myelopathy (a medical term for a disease of the spinal cord) have had corrective surgery and have experienced a dramatic decrease in their pain and fatigue along with an increase in their functional ability.” Drs. Alarcon and Bradley wrote in 1999 in response, “There is no published study or abstract cited as the source of this statement. Given that the statement is found at the end of the first paragraph describing our research on Chiari malformation, we are concerned that this work could be erroneously attributed to us.”
In 2002 Drs. Thimineur and his team reported a retrospective study on chronic pain patients, meaning they looked at chronic pain patients who had already been treated in some way or another, in which it was reported that chronic regional pain syndrome (a particular type of pain syndrome usually resulting from injury to a nerve or set of nerves), fibromyalgia, and temporal mandibular joint disorder were found to be associated with a Chiari I malformation. These authors postulated that the resulting compression could affect the part of the pain pathways that come down from the brain to dampen the pain signals in the spinal cord. This is called the “descending antinociceptive system,” and again, is described in the “Pain is in the Brain” short report.
Well, things were still not really described specifically and clinically in FMS until Dr. Daniel Heffez came on the scene. Dr. Heffez is a neurosurgeon and the director of a neurosurgical group in Chicago, Illinois and probably the major spokesperson for Chiari I malformation and FMS.
Dr. Heffez and his colleagues in 2004 published a study on 270 FMS patients the majority of which were self-referred to their center because of its nationally publicized interest in a potentially neurological basis (Chiari I malformation) for FMS symptoms. Dr. Heffez and his doctors performed a detailed neurological examination on these patients and found several abnormalities that suggested something was not right. When they extended the patients’ necks, which tightens things up in the spinal region meaning even more compression, they found that the neurological abnormalities were accentuated. The patients then had magnetic resonance imaging to see if there was evidence of the cerebellar tonsils protruding through the foramen magnum. They did see something but often not to the degree that was technically a Chiari I malformation. On average, the cerebellar tonsillar herniation was 1.1 mm, only 20% of the patients had a herniation that was > 5 mm. This was the first study to suggest something was going on in FMS that could possibly involve the spinal cord and Dr. Heffez and his team commented that this disorder had not been recognized by the any of the ten physicians their study participants had seen, on average, prior to this investigation.
Dr. Heffez published another study in 2007 to report on the 40 FMS patients from the 2004 270 patients mentioned in the above paragraph who were surgically treated. There was no significant difference in the initial clinical presentation between the patients treated by the surgical procedure or those treated non-surgically. However, the authors noted a, “striking and statistically significant improvement in all symptoms attributed to the fibromyalgia syndrome in the surgical patients but not in the non-surgical patients at 1 year…” The surgically treated patients showed improvement in their neurologic findings, improved quality of life, and improvements in anxiety and depression. Dr. Heffez and his team concluded, based on their interpretation of their findings, that a detailed neurological evaluation of FMS patients should be conducted “to exclude a treatable” medical condition.
Needless to say, this opened the door to considerable controversy. Since Dr. Heffez is a neurosurgeon he looks at the world as a surgeon. But he certainly opened some eyes with his study.
Dr. Holman, who is not a surgeon, expanded on this topic in 2008 with a pilot study in chronic pain patients to explore the potential impact of positional cervical spinal cord compression. By positional, he was investigating how changes in position affected people’s symptoms. Remember, this is what Dr. Heffez did in his examination. Dr. Heffez extended people’s necks. People extend their necks when they sit in a dentist’s chair, or when getting their hair washed in a beauty salon, or even when stretching. Dr. Holman conducted a retrospective chart review (again, looking at the medical charts of people who had already been examined) of 107 patients referred to a rheumatology clinic on whom a particular imaging study had been made. This study is called a C-spine MRI with flexion and extension midline sagittal views.
This means someone sits in an MRI machine and has images made when they bend their neck all the way forward and then all the way backward. The MRI machine then has its computer “reconstruct” or develop MRI images in the middle, or “midline sagittal” of the person’s spinal cord. This allows the radiologist to see the difference between the normal measurements of the diameter of the spinal canal, the space in which the spinal cord lives, between two extremes. One extreme is when the diameter of the spinal canal is at its maximum (the flexion view) and the other extreme is when the spinal canal is at its minimum (the extension view). In normal people, these diameters should not change.
Of the 107 patients in Dr. Holman’s study FMS had been diagnosed in 53. In these patients cervical spinal cord compression was seen in 71% of the flexion and extension films, usually extension that was seen in only 29% of the images that were taken with the person just sitting normally. Usually, when an X-ray or MRI image is taken of the neck people just sit normally and they are not asked to bend all the way forward and backward. This was the point of Dr. Holman’s study, that perhaps by not getting these two additional MRI images, the flexion and extension views, doctors were missing something important.
However, Dr. Holman found only two of the FMS patients to have a Chiari I malformation. There were no statistically significant factors that could have identified the patients. Dr. Holman did note that characteristics such as pain with prolonged extension in a hairdresser’s sink, dentist’s chair, or on examination tended to favor a positive study – just like we mentioned above. Dr. Holman also found that there were some unusual neurological findings on these patients’ charts. Dr. Holman concluded that his preliminary data suggested that additional consideration should be given to this topic.
The final study to date was published by Dr. Watson and his colleagues in 2011. When they examined 176 FMS patients they could not find a difference in the incidence of Chiari I malformation compared to their control group. They also found no evidence that the flow of cerebrospinal fluid was being restricted. These authors concluded that routine use of MRI to evaluate FMS patients was not warranted, unlike Dr. Holman’s suggestion. However, the authors did find a Chiari malformation in five of their FMS patients (2.8%) and three of the control group (4.45%).
Dr. Heffez read this study and wrote a letter to the editor of the journal in which the study appeared which was published. He pointed out that the age of the study group was 50 + 10 years which was distinctly older than most Chiari malformation patients. Dr. Heffez also drew attention to fact that Dr. Watson’s paper did not contain the results of a neurological examination, which Dr. Heffez feels is a key to identifying patients with a Chiari malformation. Dr. Heffez thought this was quite unusual as Dr. Watson had also published a paper in 2009 that was very interesting.
Dr. Watson’s 2009 paper was the first controlled study to demonstrate findings in FMS patients with a detailed neurologic exam. Dr. Watson and the authors of that paper wrote their findings supported “the possibility of a… neuroanatomic cause for the FM symptom complex, such as Arnold-Chiari I malformation, spinal canal stenosis, or postural (flexion/extension) cervical compression.” Dr. Watson’s 2009 work was important because it pointed out that FMS patients can have abnormal neurological findings, regardless of whether they have a Chiari malformation. These included problems with balance, weakness, and tingling sensations in the extremities. Given what Dr. Watson and his colleagues wrote in 2009 you can see why Dr. Heffez was perplexed.
As of 2011, the debate about the relationship between Chiari I malformation and FMS is certainly not over. Can an operation cure FMS? That question still cannot be answered definitively. Before you personally begin thinking about Chiari malformations remember their incidence in the population is very low – two or three percent. Dr. Watson actually found more in his control population than in the FMS patients. Also, it is only Dr. Heffez that has provided information on his group of patients and these were 40 patients deemed appropriate surgical candidates from an original group of 270 that came from around the country and were able to demonstrate very specific abnormalities on a neurological examination conducted by a very experienced neurosurgeon. Chiari and FMS is still a very controversial topic and one for which no decisive answer can be given. If there are any new developments, you can be assured this web site will keep you informed.