Chiari Is The Duck-Billed Platypus Of Diseases

May 20, 2006 - platypusThe duck-billed platypus (Ornithorhynchus anatinus) is a primitive animal that lives in Australia and has anatomical characteristics of several creatures that are strikingly diverse in their nature. It lays eggs and has a bill like a duck. It suckles its young like a mammal. It has a broad flat tail like a beaver. It resembles a reptile in that it has cervical ribs and uses the same opening for reproduction and the elimination of waste products. Like a scorpion it possesses a spur for injecting threatening invaders with poison. And, perhaps most unusual, like certain bony fish and some frogs, it possesses the ability to sense electric currents propagated by certain creatures that it likes to eat.

In chemistry, there is an analogy. It's element number 81, thallium. Thallium is a metallic chemical element that was discovered in 1861. Dumas once called it the "Ornithorhynchus paradoxus of metals". Its physical properties resemble that of lead's. However, chemically it behaves like aluminum to a large extent but with exceptions like forming univalent compounds similar to sodium and potassium but a weakly basic oxide similar to manganese. At this point, the reader may see where I am going. I like to think of Chiari as the Ornithorhynchus impersonatus of human diseases. We already know that Chiari is often misdiagnosed as clinical depression, multiple sclerosis, fibromyalgia and chronic fatigue syndrome because so many of its symptoms are similar to those diseases. But, it is really a much more sophisticated situation. Like Tony Curtis in the famous 1960 Hollywood movie. "The Great Imposter", Chiari plays many strikingly different roles. image 004

Let's take a closer look at Chiari in some of its lesser known but important roles in facial neuralgia, cardiac arrest, respiratory failure, hypertension, and orthostatic intolerance (fainting upon standing accompanied with drop in blood pressure). Neuralgia is a term for pain that occurs along the course of one or more nerves. There are two common facial neuralgias, trigeminal neuralgia and glossopharyngeal neuralgia. The cranial nerves involved are the fifth and ninth respectively. Of the two, trigeminal neuralgia is more frequently encountered. Facial neuralgias are extremely painful. Patients with these neuralgias find it difficult not to think about them. As a result, they often obsess about them and commonly digress into a state of clinical depression. The pain is so severe for some men with this condition that they are unable to even shave. These neuralgias are believed to be caused by a blood vessel or tumor compressing a cranial nerve. Unfortunately, many doctors, including ENTs who usually diagnose this condition, are not aware that our friendly Ornithorhynchus can also compress the lower cranial nerves to give rise to facial neuralgias. Thus, Chiari can sometimes present as a case of facial neuralgia complicated by clinical depression. Chakraborty et al1, described a 38-year-old female presenting with trigeminal neuralgia along with headache, numbness, weakness and gait abnormalities in which foramen magnum decompression resulted in complete resolution of her symptoms. However, being the great imposter that Chiari can be, cases have also been reported in the medical literature in which it has presented solely as trigeminal neuralgia with no other symptoms both in adults2 by Rosetti et al and in children3 by Ivanez and Moreno. Similarly, Chiari has been documented to present as glossopharyngeal neuralgia by Kanpolat et al4 and Aguiar et al5 as well as others. In my own case, the first diagnosis I received was mild glossopharyngeal neuralgia. The diagnosis was derived after other problems were ruled out. I underwent a CT scan to rule out tumors and a barium swallow to rule out damage to the throat from silent GERD (gastroesophygeal reflux disease). The ENT told me that he could not think of anything else other than stress that could be causing my painful swallowing symptoms.

Because the brain stem controls breathing, heart rate and blood pressure and Chiari can result in compression to the brain stem, Chiari has also cast itself in the role of cardiac arrest, respiratory failure, and blood pressure abnormalities. At least four cases of cardiac arrest caused by Chiari have been reported in the medical literature. A case of a 31-year-old man in Spain who suffered loss of consciousness and cardiac arrest with ventricular fibrillation (irregular heart beat) upon moving his head briskly was reported by Alegre et al6 in 1994. A similar case in a Polish man was reported earlier by Araszkiewicz, Haftek and Zietra7. Additionally, our platypus troublemaker, not apt to be type-cast in adult roles, has also appeared in two fatal cases of sudden unprovoked cardiorespiratory arrest in children as reported by Martinot et al8 in France.

Ornithorhynchus is also an accomplished swimmer. He has to be in order to have appeared around the world in documented cases of respiratory failure and insufficiency. Such cases have occurred not only in the United States9 but in Spain10,11, Belgium12, Saudi Arabia13, the Republic of China14, and the United Kingdom15. It is particularly interesting to note that in the Belgium case which involved a 45-year-old woman, respiratory failure was the sole manifestation with no neurological signs present.

Chiari is also well documented to cause neurogenic arterial hypertension. Turkish investigators reported a case16 in which suboccipital decompression not only provided neurological improvement but also led to resolution of the hypertension. More interesting however is a case reported by Tubbs et al17 at the University of Alabama at Birmingham involving a patient with a history of idiopathic (unknown causation) hypertension in which Chiari was ultimately determined to be the cause. Subsequent posterior fossa decompression of the patient resulted in an absence of pathologically elevated blood pressure and the patient remained normotensive at a 24-month follow-up evaluation. On the other hand, Chiari as the cause of hypotension has been more controversial. In 2001, reports in the media that decompression surgery provided benefit to patients diagnosed with fibromyalgia/chronic fatigue syndrome outraged much of the medical community as many believed there was no basis for the surgery in patients without Chiari malformations. Proponents of the treatment based their argument on a connection between Chiari and fibromyalgia/chronic fatigue syndrome. To dispel this connection, Garland and Robertson18 of the Vanderbilt University Department of Medicine, reviewed the literature for reports of orthostatic intolerance (fainting upon standing accompanied by a drop in blood pressure) in Chiari patients as patients with fibromyalgia/chronic fatigue syndrome often present with orthostatic intolerance.

The investigators found the connection between Chiari I malformation and orthostatic intolerance to be almost entirely unsupported. That was in 2001. However, more recently (2005), Prilipko et al19 of the University of Lausanne in Switzerland reported the first case of a Chiari I malformation patient with frequent recurring orthostatic intolerance whose symptoms resolved completely after surgical intervention. How could one expect anything less from the great imposter, Ornithorhynchus? Such an irresistible dramatic role simply could not be denied for long.

* pronounced: Or`ni*tho*rhyn"chus

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19J Neurol Neurosurg Psychiatry. 2005 Jul;76(7):1034-6.

Ed. Note:The opinions expressed above are solely those of the author. They do not represent the opinions of the editor, publisher, or this publication. Mr. D'Alonzo is not a medical doctor and does not give medical advice. Anyone with a medical problem is strongly encouraged to seek professional medical care.