To the medical doctor, Arnold-Chiari Malformation, which may have a genetic link, is characterized by a small or misshapen posterior fossa (the depression in the back of the skull), a reduction in cerebrospinal fluid pathways and a protrusion of the cerebellar tonsils through the bottom of the skull (foramen magnum) into the spinal canal resulting in a multitude of sensory-motor problems and even some autonomous malfunctions (1). These many symptoms can come in a variety of forms which often makes a clinical diagnosis difficult. To the patient this disorder can present not only physical difficulties but also mental distress. Treatment options and their success rates vary widely, and proponents of the cause are demanding more recognition, research, and success. The study of Arnold-Chiari malformations can lead to additional questions and new understandings about the I-function, sensory-motor input/output paths and the general make-up of the brain and nervous system, but a complete understanding of the disorder may be a long time coming.
Impairment and sometimes loss of motor control of the body and its extremities is one of the many effects of this disorder. Patients may complain of headaches, neck pain, coughing, sneezing, dizziness, vertigo, disequilibrium, muscle weakness, balance problems, and loss of fine motor control (1). The senses (hearing, sight, smell etc.) may also be affected in deleterious ways. On can have blurred vision, decreased sensation of limbs, unable to locate them without looking, decreased sense of taste, ringing of the ears etc. (2).
Two ideas about the nervous system that can be better understood from these observations are the concepts of having and locating the I-function. It seems that the I-function here is very often affected in terms of voluntary movement. A person with Arnold-Chiari malformation who has lost the feeling in and control of his arm for example will not be able to move it even upon someone's request and his or her own desire to do so. Some use of the I-function is definitely impaired. However, these observations do not seem to necessarily imply that some part of the I-function was damaged, because it may very well be located elsewhere- connections may have simply been lost. A person with Arnold-Chiari can still think and have a sense of self, but somehow can not connect with the various body parts that can be affected. Some uses and pathways of the I-function can be understood, but the exact location of it remains vague.
A lack of sensory input can also provide clues about pathways within the nervous system. Depending on the severity and specific location of the Chiari malformation different senses may be affected. Again, the location of where this information is processed can not be determined for sure from these observations alone. It is obvious that the pathway needed for sensory information to travel is indeed affected but not the ultimate processing center itself.
Recently, diagnosing this disorder has become relatively easier with the advent of the MRI (magnetic resonance imaging) so that doctors and patients no longer have to rely on a symptom-based diagnosis which was troublesome for both (3). The symptoms vary widely and encompass many parts of the body. Many deemed Arnold-Chiari sufferers the victims of some psychosomatic disease before the biological nature of the disorder was understood (5). Now, with the possibility of having a genetic predisposition for Chiari and the early detection devices available, one can more easily be diagnosed properly (2).
There are both medical and non-medical ways to treat Arnold-Chiari malformations. When symptoms develop, patients should seek a doctor's advice to consider a posterior fossa and upper cervical decompression. This procedure can provide more room around the lower brainstem and promotes improved neurologic functioning, though it is not a guaranteed solution (3). Patients may also benefit from various and symptom appropriate forms of physical and occupational therapy. Some patients also explore non-traditional options such as herbal therapy, acupuncture and others (5).
The symptomology of Arnold-Chiari malformations can lead to many useful observations of the pathways used by the nervous system to maintain control and awareness of the body in terms of the I-function and sensory-motor abilities. However, due to this large range of symptoms and the fact that current attempts to treat them all are not always successful, there may be other things going on in other areas of the nervous system which contribute to the overall effect of Chiari. The situation at the base of the skull, where the malformations are readily noticeable and are thought to be the cause, may be more complicated then believed or known at the time. As always, a better understanding of what is actually happening in patients with Arnold-Chiari malformation is needed.
