SDNDS - Movement and Pain Disorders

Parkinson’s Disease was originally described by James Parkinson in the early 1800’s, who called the condition paralysis agitans because of the tremor and lack of control of movement frequently associated with this condition. Parkinson’s Disease is one of a variety of dyskinesias, or involuntary movement disorders. It is referred to as an "involuntary disorder," since it generally cannot be controlled by the will, and patients find that their motor activity occurs and persists despite their desires. Parkinson noted in his original monogram that certain conditions like strokes which induced paralysis, could alleviate some symptoms of the condition, and surgeons later began performing various procedures originally aimed at producing partial paralysis as a desperate attempt to relieve some of the sufferings of patients with this condition.

In the late 1940’s, Spiegel and Wycis introduced the concepts of stereotaxic surgery to the armamentarium of human neurosurgery, and thus ushered in the use of stereotaxy for the treatment of dyskinesia. These clinicians used the stereotaxic technique to perform a surgical procedure on the basal ganglia, which was similar to an operation for Parkinson’s Disease originally introduced by Russell Myers in 1942. Their surgical target was the globus pallidus (pallidum) and its fiber outflow pathways to surrounding brain structures. This technique was perfected between 1948 and 1954 and was essentially the original pallidotomy. The targeted portion of the globus pallidus was the dorsal lateral (upper/outer) portion of that structure. Many subsequent surgeons performed this procedure, which was at that time considered to be fairly efficacious for the treatment of Parkinson’s Disease. Lesions (carefully controlled selected damage) of this part of the brain was fairly effective in relieving some of the symptoms of Parkinson’s Disease. In about 60% to 80% of patients, there was some relief of bradykinesia, rigidity and to a lesser extent, tremor.

This target sire in the globus pallidus was used in a large number of surgical procedures performed around the world until 1955. Since the former pallidotomy was not totally effective in relieving the tremor and rigidity of Parkinson’s Disease, there continued to be a search for a more effective target site. The studies of Rolf Hassler in Germany ultimately led to the use of a new target site in another part in the brain known as the thalamus. As an anatomist and neurophysiologist, Hassler postulated that the fiber pathways from the globus pallidus, as well as fibers from the cerebellum, which converged in a portion of the thalamus known as the ventral medial nucleus, would perhaps be a more effective site for the surgical treatment of Parkinsonian symptoms. Thus, the period of thalamotomy (surgery on the thalamus) was started as an effective treatment for Parkinson’s Disease. This site was effective primarily for the relief of tremor and rigidity, of which there was as high as 90% to 95% chance of relieving or reducing these symptoms. This target site was less effective for the other symptoms of Parkinson’s Disease, most notably bradykinesia, gait disturbances, freezing and other symptoms. Thalamotomy became a very popular method for the surgical treatment of Parkinson’s Disease, and this was further reinforced by the studies of Claude Bertrand, Gilles Bertrand and Herbert Jasper in Montreal, and other clinicians, such as Madame Albe-Fessard in France, who by the use of very fine micro-electrode recording of brain cellular activity in the thalamus, found cells which had electrical activity, that was synchronous with tremor. This part of the brain was referred to as the "Tremogenic Zone" and this was held as a target of choice for the treatment of Parkinson’s Disease. Many stereotaxic surgeons around the world perfected this technique.

In the late 1960’s, the relationship of L-Dopa to the genesis of Parkinson’s Disease was discovered. Various researchers noted that there was a deficiency of dopamine in a part of the brain called the substantia nigra in patients with Parkinson’s Disease. It was therefore advocated that the replacement of this chemical compound in the brain would alleviate the symptoms of Parkinson’s Disease. Ultimately, Sinemet was introduced as the drug of choice for the treatment of Parkinson’s Disease. Sinemet was effective as a treatment for Parkinson’s Disease and surgery was ultimately rarely offered as a treatment. The incidence of the surgical treatment of Parkinson’s Disease fell to an extremely low level, so much so that since the 1970’s, very few neurosurgeons have been taught the use of stereotaxic surgery for the treatment of this disorder. Though Sinemet remains effective in the treatment of Parkinson’s Disease, (most notably bradykinesia, gait disturbances, speech disturbances, and other symptoms with lesser effect on tremor and rigidity), it seems to be most effective in the initial 4 to 5 year period of use. It has also been responsible, however, for the production of "drug-induced dyskinesias," and, in many cases, these drug-induced symptoms are worse than the dyskinesias of Parkinson’s Disease.

In view of the problem with the use of Sinemet, and the fact that it has less effect on the treatment on tremor and rigidity, searches for other methods for the treatment of Parkinson’s Disease have continued. These methods have included fetal tissue transplants and adrenal gland transplants with a view toward grafting cells into the brain which will produce L-Dopa, and thus obliviate the need to give medication to replenish this chemical substance. These tissue transplant methods have not been widely accepted and are generally regarded as investigational.

Recently, Lauri V. Laitinen (1992) has re-evaluated work done by Lars Leksell in the 1970’s and re-introduced pallidotomies. The new site involves a different portion of the globus pallidus referred to as the ventral posterior mesial pallidum (inner/lower back portion). This site is different from the previously advocated dorsal/lateral pallidotomy, and has been found to be effective in relieving the majority of the symptoms of Parkinson’s Disease, including drug-induced dyskinesias from the use of Sinemet.

In summary, the primary surgical methods used in the treatment of Parkinson’s Disease include thalamotomy and pallidotomy and the procedure is selected on the basis of the major symptoms of Parkinson’s Disease present in a given patient. Surgery is generally reserved as an alternative method for the treatment of Parkinson’s Disease and should be used after a well-controlled trial of drug therapy has been used and found to be insufficient for the relief of significant Parkinsonian symptoms. The table below summarizes the symptoms treated by the various surgical sites.

	Surgical Indications:
Thalamotomies:	Primary unilateral or bilateral tremor (and rigidity) which responds poorly to medications.
Pallidotomies:	Bradykinesia and rigidity greater than tremor Parkinsonian symptoms and "on" dys-kinesias worse on the same side of the body. Severe "on-off" fluctuations in response to small amounts of anti-Parkinson medications.