Brain Surgery
The MRI on the left shows the planned trajectory to place a stimulating electrode into the brain to treat Parkinson's Disease.
Case Report
Parkinson's Disease and Tremor
Board Certified by the American Board of Neurological Surgeons
Parkinson's Disease (PD) is the most prevalent movement disorder. While there are 15 new cases of PD per 100,000 persons annually, the number of people living with Parkinson's disease is much higher. The diagnosis of PD is clinical, based upon the presence of at least two of the three clinical hallmarks of PD (tremor, bradykinesia, and rigidity) and a favorable response to medicine (Sinemet). There is a spectrum of clinical signs and symptoms as well as a long differential list of possible confounding diagnoses that have a different clinical course and response to therapy. The hallmarks of PD include a resting tremor, muscular rigidity, masked face, and bradykinesia. Bradykinetic symptoms include slow initiation of movement, freezing, short steps, festinating gait, reduced spontaneous movements, micrographia, difficulty arising from a chair, postural instability, dysphonia, dysarthria and dysphagia. The initial symptoms of PD, mild unilateral tremor or decreased arm motion with ambulation, are often missed until the patient develops additional symptoms. With progressive bradykinesia and rigidity, patients may suffer respiratory distress. PD may include psychological symptoms such as anxiety, depression, hallucinations and poor memory and concentration.
Patients without significant tremor are often more difficult to recognize. Early signs may include complaints of fatigue, slightly increased muscle rigidity, failure to swing the arm while walking, difficulty standing up from the sitting position, and extinction of the blink reflex with tapping on the bridge of the nose (Myerson's sign).
PD presenting in the adult population is most often due to the loss of neurons that make dopamine. These neurons are located in a small distinct portion of the brainstem known as the substantia nigra. Children or young adults with Parkinsonian features should be suspected to have hepatolenticular degeneration, a medical problem with similar clinical manifestations.
The differential diagnosis of PD includes the Parkinson's plus syndromes (or multiple system atrophy disease). These degenerative disorders need to be recognized as they respond poorly to surgery. Such conditions include Shy-Drager syndrome, striatonigral degeneration, progressive supranuclear palsy, olivopontocerebellar degeneration, and the "multiple system atrophy" disorders. Clinically, signs of autonomic dysfunction, long tract signs, cerebellar deficits, extraocular movement abnormalities, increased axial tone and a lack of response to L-dopa therapy are indicators that a Parkinson plus disorder exists. In addition to thorough neurological assessment, pre-operative computed tomography and magnetic resonance imaging are important to exclude multi-infarct dementia. Positron emission tomography (PET scan) has been shown to distinguish progressive supranuclear palsy and corticobasal degeneration from PD.
Even with the proper diagnosis, it remains challenging to choose the best surgical procedure for a given set of clinical problems. My current practice is to perform a pallidotomy or place a stimulating electrode into the brain for those patients who are most disabled by dopa-induced dykinesias, with or without tremor. Because pallidotomy does not consistently treat tremor, PD patients affected primarily by tremor are recommended to have a thalamotomy or placement of a thalamic stimulator. Some patients may be considered for Gamma Knife thalamotomy. It has been suggested that stimulation of the subthalamic nucleus relieves akinesia, levodopa induced dyskinesias, tremor, and rigidity. It has also been suggested that bilateral stimulation of the subthalamic nucleus (STN) may alter the progression of the disease. STN stimulation can be performed bilaterally with an acceptable rate of complications. At this time, a definitive long-term experience of STN stimulation is not available and only performed as part of experimental protocols. The difference between the pallidotomy, thalamotomy and deep brain stimulator is described in the section on Neurosurgical Procedures.
ESSENTIAL TREMOR
Essential tremor, unlike a Parkinsonian tremor, is absent at rest. It occurs with sustained action or postures. Essential tremor is fairly common, affecting approximately 400 persons among every 100,000 over the age of 40. The degree of tremor may be variable, from mild to severe and incapacitating. The tremor typically affects the upper extremities, but may also affect the legs, head, and neck. While some relief may be obtained with medicines, thalamic stimulation and thalamic ablation procedures (thalamotomy) are also useful. The procedures are the similar to those described for Parkinson's disease. The Gamma Knife may be used as a non-invasive method of performing a thalamotomy.
SPASTICITY
Spasticity is a velocity dependent increase in muscular tone that occurs with movement against passive stretch. Spasticity is the result of hyperactivity of the muscle stretch reflexes. Many disease processes can cause spasticity including spinal cord injury, cerebral palsy, multiple sclerosis, stroke, and traumatic brain injury.
Spasticity is most often treated with medicines. Severe spasticity may also be treated with a number of surgical procedures. The most recent advance in the management of spasticity is the infusion of medicine (baclofen) around the spinal cord by an implanted pump. To determine if a pump is an effective means of treating an individual's spasticity, patients initially undergo a trial during which baclofen in instilled into the fluid around the spinal cord. If the medicine significantly reduces the spasticity, a pump may be implanted under the skin to allow an adjustable daily infusion of baclofen.
PROCEDURES FOR MOVEMENT DISORDERS
Stereotactic Pallidotomy & Thalamotomy
Deep Brain Stimulation, Targeting the subthalamic nucleus, thalamus, of globus pallidus
Gamma Knife, targeting the Thalamus (tremor only)
Baclofen Pumps (for spasticity)
PUBLICATIONS:
Thompson TP, Lunsford LD, Kondziolka D. Technical considerations in movement disorder surgery: frames, imaging, and intraoperative monitoring. Progress in Neurological Surgery, 15; 91-102, 2000
Thompson TP, Lunsford LD, Kondziolka D. Restorative Neurosurgery. Opportunities for Restoration of Function in Acquired, Degenerative, and Idiopathic Neurological Diseases. Neurosurgery 45(4):741-752, 1999
Thompson TP, Kondziolka D, Lunsford LD. Movement Disorder Surgery. Contemporary Neurosurgery, 21(16):1-6, 1999
Thompson TP, Lunsford LD, Albright AL. Patient Selection in Movement Disorder Surgery in Yeoman's Neurological Surgery. Fifth ed. Vol 3, pp 2745-2753, Winn HR ed. Elsevier Inc., Philadelphia, 2004
Thompson TP, Kondziolka DK, Albright AL. Thalamic Stimulation for Choreiform Movement Disorders in Children. J Neurosurgery 92:718-721, 2000
