Functional Neurosurgery

Movement Disorders

Movement disorders refer to a group of neurological conditions that result in disorders of normal body movements. This may refer to conditions that slow down body movements such as Parkinson's disease or conditions that are associated with abnormal or increased body movements. The disorders we often see in our movement disorders clinics include:

Ataxia

Impaired ability to coordinate voluntary movements that may result in problems with walking and balancing.

Chorea

Jerky, irregular, relatively rapid, involuntary movements that can affect the face or limbs.

Dystonia

Slow, twisting, involuntary movements associated with forceful muscle contractions or spasms. This may affect the eyes (blepharospasms), muscles of the face, jaws, neck, upper limbs and/or lower limbs. At times these spasms occur on performing a specific task such as writing (writer's cramps).

Hemifacial spasms

Involuntary twitching or spasms that affect one half of the face, including the eye muscles, resulting in uncontrollable eye closure.

Myoclonus

Brief, involuntary, jerk-like twitching or contractions of muscles.

Tics

Repetitive, purposeless muscle movements (motor tics) or vocalisations (vocal tics) that arise from an irresistible urge that is temporarily relieved following the execution of the movement or vocalisation.

These abnormal movements may arise from a variety of diseases and careful evaluation is necessary to determine the underlying cause. After the type of abnormal movement has been classified and the cause established, the next step is to reduce the frequency or severity of these movements so as to improve function or reduce discomfort. Oral medications are the main type of treatment used to control these movements. For some of these disorders such as facial spasms or dystonia, botulinum toxin injections may be useful to relieve the symptoms.

Parkinson's Disease (PD)

Parkinson's disease (PD) is the 2nd most common neurodegenerative disorder after Alzheimer's disease. A recent study in Singapore showed that PD occurs as commonly as in the West. 3 out of every thousand individuals, aged 50 years and above, have this disease. PD is a progressive neurological disorder caused by a loss of nerve cells in the substantia nigra, a region within the brainstem. In most cases, the cause of PD is unknown. The onset of PD is insidious and occurs during the 4th and 5th decade of life. The symptoms of the disease consists of a resting tremor, stiffness and slowness of movements. Patients also develop uncontrolled abnormal movements as well as difficulties in movement. Other common signs include a expressionless face, softer voice, smaller handwriting, drooling of saliva, difficulty swallowing, and walking difficulties. There is no simple laboratory test to diagnose PD and the doctor makes the diagnosis based on a set of symptoms or signs.

PD is a slowly progressive disorder and there is currently no cure. There are however effective medications that can improve the symptoms of the disease. Your doctor will be able to recommend the most appropriate medications depending on your symptoms, age, and other medical conditions. Treatment has to be individualised and medications that are suitable for one patient may not be ideal for another. For patients with more advanced disease with failed medical therapy, a surgical procedure called deep brain stimulation may further improve symptoms. This involves the implantation of wire electrodes into precisely located regions of the brain to electrically stimulate that area and reduce the symptoms of PD. This procedure is done under a semiconscious state and involves a multidisciplinary team of doctors and electrophysiologists.

Trigeminal Neuralgia

Trigeminal neuralgia is characterised by brief episodes of extremely intense facial pain often radiating to the jaw. These episodes can occur spontaneously or can be triggered by light touch, chewing, or changes in temperature. Trigeminal neuralgia is caused by irritation of the fifth cranial nerve (the trigeminal nerve) which is responsible for providing sensation to the face. This irritation can occassionally due to benign tumors or other neurological conditions which need to be excluded by an MRI brain scan. Often, the cause is due to a small vessel found to be compressing the root entry zone of the trigeminal nerve at the brainstem.

The initial treatment of this condition is by medical therapy. This involves the use anticonvulsants such as Tegretol (carabamazepine) and related medications. Surgery is reserved for those who are unable to tolerate the side effects of these medications or for whom these medications are no longer effective. The surgical procedure is known as a microvascular decompression. During surgery, the vessel causing the problem is repositioned this vessel using microsurgery. The majority of patients who have this procedure performed are pain free, requiring no further medications.

Other forms of treatment if surgery is not suitable is the use of radio frequency abalation for pain control or by injection of certain agents around the nerve at the base of the skull to produce relief of symptoms and gamma knife radiosurgery.

Percutaneous radiofrequency abalation uses a special needle inserted in the face and radiofrequency-generated heat energy to selectively damage the trigeminal rootlets. It is carried out in the awake patient and requires his co-operation and accurate feedback for proper positioning of the needle. It causes irreversible facial numbness. Precise control of the extent of the lesion is not always possible. Abnormal, unpleasant sensations of itching, burning or crawling (20% patients) can accompany facial numbness. When severe (0.3%), they are as distressing to the patient as their original pain, since they can be present continuously as a severe burning discomfort (anaesthesia dolorosa or analgesia dolorosa) which does not respond to treatment. Loss of feeling in the first Trigeminal division makes the cornea insensate, and leaves the patient at risk for corneal ulceration and can lead to loss of vision.

Percutaneous glycerol chemoneurolysis is also carried out using a needle inserted in the face and is usually done under local anaesthesia. There is usually only mild sensory loss as compared with radiofrequency abalation. The pain recurrence rate is however higher, but this is not a significant disadvantage, as the procedure can be easily repeated and is well tolerated.

Gamma knife radiosurgery uses intense gamma rays directed at the Trigeminal nerve root. However long-term data comparable to that reported for other procedures is lacking. Results of treatment are variable and studies have shown 50-90% reduction of pain as good and 10-50% as fair.

The choice of treatment for trigeminal neuralgia depends on the patient's age, associated illness and assessment of the risks he is willing to assume. For most "younger" patients, microvascular decompression is the best option. Younger patients have a better chance of tolerating surgery without complications, and a longer future life expectancy in which to deal with problems that can follow percutaneous lesioning. They also have a higher risk of pain recurrence following such procedures and will likely need more future treatments resulting in an increased cumulative side-effects.

Older patients (>65-70 years of age) have increased risks of surgical complications. But because of shorter overall life expectancy, they likely will require fewer repetitions of percutaneous procedures with less cumulative denervation sequelae. Significant associated illness such as chronic obstructive pulmonary disease, coronary artery disease and diabetes mellitus can also increase the risks of such major surgery.

Glossopharyngeal Neuralgia

Glosspharyngeal neuralgia is similar to trigeminal neuralgia but is thought to be caused by irritation of the ninth cranial nerve (the glossopharngeal nerve) which is responsible for providing sensation to the back of the throat. Patients experience episodes of to this region. Treatment options are similar to those outlined for trigemenial neuralgia above.

Hemifacial Spasm

Hemifacial spasm is a condition characterised by facial muscle spasms or tics. These tics are usually painless and affect one side of the face. The cause is thought to be due to irritation of the seventh cranial nerve (the facial nerve). A small artery or vein is often found to be compressing the root entry zone of the facial nerve at the brainstem. Medical treatment for this condition may be effective in some patients. In the majority, surgery is the treatment of choice and involves repositioning this vessel using microsurgery. The majority of patients who have this procedure performed have no further facial tics and require no further medications. Injection of botulinum toxin into the face to produce a temporary partial paralysis is an alternative treatment option but needs to be repeated approximately every six months.

Sweaty Palms (Palmar Hyperhidrosis)

Sweaty palms (Palmar hyperhidrosis) is a physical condition with uncontrollable excessive hand sweating. It may cause severe psychological, social and/or professional disability. Problems such as difficulties handling paper, pens, buttons, tools, electronic equipment, as well as the need to avoid handshakes force many people to seek treatment. This problem is also often associated with increased sweating in the armpit regions and in the soles of the feet.

The cause for the excessive sweating is still unknown but the condition is related to over-activity in the sympathetic nervous system which is a system of nerves over which we have no control.

For severely affected individuals in whom standard medical treatments have failed, surgical treatment for the problem is an option. This involves cutting a short segment of the "sympathetic nervous system" which is a chain of nerves running alongside and parallel to the spinal column in the chest region.

The surgical proceduce that is now performed is called an Endoscopic Transthoracic Sympathetomy. This procedure uses an endoscopic (keyhole) technique to interrupt the sympathetic nervous system and is a reliable operative technique to completely eliminate severe hand sweating and sweating in the armpits. It has to be emphasised that this procedure is not meant to treat the problem of increased sweating over the trunk of the body or lower limbs and feet. This surgical procedure is performed under general anaesthesia and requires 1- 2 nights' stay in the hospital.

The operation is done through a single 1 cm incision in the armpit region. The endoscope is inserted and the lung is collapsed. A short section of the sympathetic nervous system is exposed and cut. The instruments are removed and the lung is allowed to re-expand. A "chest tube" to ensure that air in the thoracic cavity will be completely removed and the lung is able to re-expand fully. The skin incisions are closed with stitches and then covered with sterile dressing. The procedure is repeated on the opposite side and after the operation, the chest tubes are then removed.

Post-operatively, patients will notice immediate improvement in the symptoms of sweating. Complications from endoscopic transthoracic sympathectomy are low but as with any surgical procedure, endoscopic transthoracic sympathetomy is associated with some degree of risk. Air-leak from the lung occurs in approximately 1% of patients and the treatment is by a chest drainage tube placed between two ribs and connected to a suction device for 1-2 days. The patient has to stay in the hospital until the tube is removed. Severe bleeding in the chest during the operation, although rarely reported, could necessitate a repeat operation which involves a larger skin incision to open the chest cavity and identify the source of bleeding to stop it. A specific complication called Horner's Syndrome can occur and refers to the slight drooping of an eyelid and a slightly smaller pupil, without visual impairment. This occurs in approximately 1% of patients, and disappears spontaneously without specific treatment in about half of these patients.

An important side effect of this procedure that occurs in up to 40% of patients is the problem of "compensatory sweating". This is the phenomenon of increased sweating of the legs and trunk after surgery and may or may not resolve gradually with time.