Patients are often frustrated when their physicians do not understand or ignore the diagnosis of Chiari I malformation (CM-I). For those affected, the diagnosis may be delayed for several years. The reasons for this lack of awareness of CM-I are multiple:
1. Little time spent in medical school on the Chiari malformations. With thousands of medical diseases and disorders and limited time, medical school curricula emphasize major diseases such as cancer, heart disease, stroke, and trauma. Little if any time is spent on CM-I, a disorder previously considered rare. The trend toward individual case studies and fewer lectures, while allowing more in-depth study of specific disorders, further reduces the total number of disorders studied.
2. The clinical presentation of CM-I is broad and variable. Many neurological disorders are recognized by their characteristic symptoms. Normal pressure hydrocephalus, for example, has only three important clinical signs: dementia, ataxia, and urinary incontinence. However, patients with CM-I frequently present with a variety of symptoms that often differ from one patient to the other. Over 40 different symptoms may occur. Some rare presentations of CM-I, such as paroxysmal rage in toddlers, make recognition of the disorder even more difficult.
3. A cursory neurological exam is often normal. Major neurological abnormalities are usually absent in patients with the Chiari I malformation and a brief neurological examination is frequently normal. The lack of obvious findings can lead physicians to conclude that nothing is wrong. However, a more detailed examination may reveal a variety of neurological findings including nystagmus, double vision, facial numbness, absent gag reflex, weakness or numbness in the extremities, and impaired fine-motor function. Deep tendon reflexes may be abnormally brisk or tandem gait may be unsteady.
4. Other disorders cause similar symptoms. The symptoms noted by patients suffering from the CM-I can be caused by other disorders. The differential diagnosis for CM-I is wide and includes idiopathic intracranial hypertension (pseudotumor cerebri), spontaneous intracranial hypotension, occipital neuralgia, cervicogenic headaches, and others. Each of these disorders has a number of symptoms in common with CM-I and can be difficult to distinguish.
5. The Chiari malformation may be reported as “incidental”. Unfortunately, even if MRI shows a Chiari I malformation, it may not be recognized as an important finding if the radiologist reports it as incidental. The requesting physician reading “normal scan, incidental Chiari malformation” may be thrown off track and believe nothing of importance was found. This can occur even when the indication for the scan was headaches, dizziness, or visual disturbances. Even if the Chiari malformation is not the cause of the symptoms, the physician examining the patient should decide the relevance of the finding. If the examining physician is unfamiliar with the Chiari malformation, the patients should be referred to a neurologist or a neurosurgeon.
6. Neurologists or neurosurgeons may discount its importance. In some cases, the family physician appropriately orders an MRI revealing 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. The lack of training on CM-I in some neurology and neurosurgery training programs is a factor, but there seems to be more to it than this.
Some neurologists and neurosurgeons are not aware that patients can have a number of neurological symptoms from what appears on MRI to be a “mild” Chiari malformation. Others may not be aware of, or have access to, CINE MRI, an MR scan that visualizes spinal fluid flow at the craniocervical junction. This specialized MRI, along with a careful consideration of the symptoms and neurological findings, is especially helpful in the patient diagnosed with a “mild” Chiari malformation.
Fortunately, education and increased awareness can go a long way to overcoming these concerns. Steady increase in awareness of this disorder, further research, such as a currently planned multicenter trial on surgical outcome, and the efforts of a variety of support and advocacy organizations, should lead to earlier recognition of the Chiari I malformation.
Posted byJohn Oro', MD
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Patients are often frustrated when their physicians do not understand or ignore the diagnosis of Chiari I malformation (CM-I). For those affected, the diagnosis may be delayed for several years. The reasons for this lack of awareness of CM-I are multiple:
1. Little time spent in medical school on the Chiari malformations. With thousands of medical diseases and disorders and limited time, medical school curricula emphasize major diseases such as cancer, heart disease, stroke, and trauma. Little if any time is spent on CM-I, a disorder previously considered rare. The trend toward individual case studies and fewer lectures, while allowing more in-depth study of specific disorders, further reduces the total number of disorders studied.
2. The clinical presentation of CM-I is broad and variable. Many neurological disorders are recognized by their characteristic symptoms. Normal pressure hydrocephalus, for example, has only three important clinical signs: dementia, ataxia, and urinary incontinence. However, patients with CM-I frequently present with a variety of symptoms that often differ from one patient to the other. Over 40 different symptoms may occur. Some rare presentations of CM-I, such as paroxysmal rage in toddlers, make recognition of the disorder even more difficult.
3. A cursory neurological exam is often normal. Major neurological abnormalities are usually absent in patients with the Chiari I malformation and a brief neurological examination is frequently normal. The lack of obvious findings can lead physicians to conclude that nothing is wrong. However, a more detailed examination may reveal a variety of neurological findings including nystagmus, double vision, facial numbness, absent gag reflex, weakness or numbness in the extremities, and impaired fine-motor function. Deep tendon reflexes may be abnormally brisk or tandem gait may be unsteady.
4. Other disorders cause similar symptoms. The symptoms noted by patients suffering from the CM-I can be caused by other disorders. The differential diagnosis for CM-I is wide and includes idiopathic intracranial hypertension (pseudotumor cerebri), spontaneous intracranial hypotension, occipital neuralgia, cervicogenic headaches, and others. Each of these disorders has a number of symptoms in common with CM-I and can be difficult to distinguish.
5. The Chiari malformation may be reported as “incidental”. Unfortunately, even if MRI shows a Chiari I malformation, it may not be recognized as an important finding if the radiologist reports it as incidental. The requesting physician reading “normal scan, incidental Chiari malformation” may be thrown off track and believe nothing of importance was found. This can occur even when the indication for the scan was headaches, dizziness, or visual disturbances. Even if the Chiari malformation is not the cause of the symptoms, the physician examining the patient should decide the relevance of the finding. If the examining physician is unfamiliar with the Chiari malformation, the patients should be referred to a neurologist or a neurosurgeon.
6. Neurologists or neurosurgeons may discount its importance. In some cases, the family physician appropriately orders an MRI revealing 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. The lack of training on CM-I in some neurology and neurosurgery training programs is a factor, but there seems to be more to it than this.
Some neurologists and neurosurgeons are not aware that patients can have a number of neurological symptoms from what appears on MRI to be a “mild” Chiari malformation. Others may not be aware of, or have access to, CINE MRI, an MR scan that visualizes spinal fluid flow at the craniocervical junction. This specialized MRI, along with a careful consideration of the symptoms and neurological findings, is especially helpful in the patient diagnosed with a “mild” Chiari malformation.
Fortunately, education and increased awareness can go a long way to overcoming these concerns. Steady increase in awareness of this disorder, further research, such as a currently planned multicenter trial on surgical outcome, and the efforts of a variety of support and advocacy organizations, should lead to earlier recognition of the Chiari I malformation.
Posted byJohn Oro', MD