Why is the Chiari Malformation Frequently Unrecognized or Ignored?

Many persons are frustrated when physicians don't understand or ignore the diagnosis of Chiari I malformation (CMI). This often leads to visits to multiple physicians and increases frustration and disillusionment with the health care system. In one of our analyses, we noted an average duration of symptoms before correct diagnosis was 6 years. There are multiple reasons for the lack of understanding of the Chiari I malformation in the medical community including the following.
1. Little time is spent in medical school on the Chiari malformations. With thousands of medical diseases and disorders and limited time, medical education is often focused on the major diseases such as cancer, heart disease, stroke, gastrointestinal disease, urological or gynecological disorders, and trauma. CMI, previously considered rare, is often given a limited, if any, place in the medical curriculum. Even now with the increasing recognition of CMI, it will take time for medical school curriculums to adjust. Another factor is the trend to fewer lectures and more individual case studies which, while allowing more in-depth study of specific disorders, further reduces the total number of disorders a medical student studies. The move to a case-study approach occurred due to the recognition that physicians will never learn all the disorders in medical school and must become lifelong learners. Thus, organizations promoting education in the Chiari malformation and syringomyelia, now have a greater role and responsibility in continuing the education of medical professionals.
2. The clinical presentation of CMI is broad and variable. Patients with neurological disorders often present with a number of symptoms and findings on examination which, in medical terms, is called the clinical presentation. Many neurological disorders have characteristic symptoms that are usually recognized by physicians. For example, the condition of Normal Pressure Hydrocephalus (NPH) has only three important clinical findings: dementia, difficulty walking, and bladder problems. However, persons with CMI usually have multiple symptoms, and the symptoms may differ from one person to the other. Thus the clinical presentation of someone suffering from CMI can vary widely. In one of our studies we showed over 40 different symptoms may occur, and even this list is not complete. Compare that to our example of NPH with only three key symptoms and one begins to see the difficulty in suspecting the presence of a Chiari malformation.
3. A cursory neurological exam is often normal. Major neurological abnormalities are often absent in patients with the Chiari I malformation and a brief neurological examination is often normal. Since physicians rely on detecting abnormal neurological findings in order to diagnose most neurological disorders, the lack of obvious findings in many patients with CMI can lead physicians to conclude that nothing is wrong.
However, on more careful evaluation, neurological deficits are often found and may include nystagmus, double vision, facial numbness, loss of gag reflex, subtle weakness in the extremities or decreased sensation. The reflexes may be abnormally brisk, or heel-to-toe walking may be unsteady. With eyes closed, a patient may loose their balance when gently tapped by the physician. Headache may be worsened with bending forward or looking up.
Other disorders can cause the symptoms seen in CMI.
Patients suffering from the CMI often have multiple symptoms. However, each symptom can be caused by other disorders. After the patients symptoms are determined and a neurological exam is performed, the physician considers the multiple disorders that may cause similar symptoms and findings. This is called the differential diagnosis. The differential diagnosis of patients evaluated for the CMI is large and includes disorders such as:
Chronic fatigue syndrome, Cluster headache, Degenerative cervical disc disease
Fibromyalgia, Hydrocephalus, Lyme disease, Migraine, Multiple sclerosis
Occipital neuralgia, Peripheral neuropathy, Pseudotumor cerebri,
Post-concussion syndrome, Posterior fossa arachnoid cyst, Psychiatric disease
Sleep apnea, Spinal CSF leak, Vasculitis

While some of these disorders have only a few symptoms that overlap with CMI, others, such as pseudotumor cerebri, have many symptoms in common. Thus, without an MRI, making the diagnosis of CMI can be difficult.
The Chiari malformation may be reported as "incidental" by some radiologists. Unfortunately, even if an MRI shows the presence of a Chiari I malformation, it may still not be recognized as an important finding if the radiologist preparing the scan report uses the word incidental. Incidental means that something has been found, but is of no importance. Since saying that something is of no importance is a clinical decision, the decision should not be made by the radiologist since they have not taken a clinical history or performed a careful neurological examination on the patient.

When the physician who ordered the test reads words such as "normal scan, incidental Chiari malformation", they can get thrown off the track and believe nothing of importance was found on the scan. Imagine, scheduling a scan for a person complaining of worsening headaches and essentially being told that there was nothing found other than an "incidental Chiari". Even if the Chiari malformation is not the cause of the headache, the decision of the relevance of the finding should be made a physician that has interviewed and examined the patient. If the physician examining the patient is unfamiliar with the Chiari malformation, the patient should be referred to a neurologist or a neurosurgeon who is.

Even some neurologists or neurosurgeons discount the importance of CMI. In some cases, the family physician appropriately orders an MRI that reveals a Chiari malformation and appropriately refers the patients to a neurologist or neurosurgeon, only to find that the diagnosis is discounted. The reasons for this are complex and difficult to understand. One cause is the lack of training on CMI in some neurology and neurosurgery training programs. But there seems to be more to it than this.
Some neurologists and neurosurgeons are not aware that some patients may have a number of neurological symptoms from what may appear on MRI to be only a "mild" Chiari malformation. Many, may not be aware, or may not have access to a specialized MRI called the CINE flow study that can help determine if there is spinal fluid obstruction and therefore increasing the possibility that the "mild" Chiari is responsible for the patients symptoms.

Thus, there are a number of reasons why many physicians, and even some neurologists and neurosurgeons, don't understand or ignore the Chiari malformation. Much work remains to be done. This organization has been established to enhance our knowledge of CMI and related conditions and is an important part of the solution.
Dr. Oro, MD
Chiari Connection International