Thalamotomy (; ) is a surgical procedure in which a functional lesion is made into the

thalamus The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of ...

to improve the overall brain function in patients. First introduced in the 1950s, it is primarily effective for tremors such as those associated with

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor system, motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become ...

, where a selected portion of the

is surgically destroyed ( ablated). Neurosurgeons use specialized equipment to precisely locate an area of the thalamus, usually choosing to work on only one side (the side opposite that of the worst tremors). Bilateral procedures are poorly tolerated because of increased complications and risk, including vision and speech problems. The positive effects on tremors are immediate. Other less destructive procedures are sometimes preferred, such as subthalamic deep brain stimulation, since this procedure can also improve tremors and other symptoms of PD.

Indications

Thalamotomy is a complex procedure performed by specialist neurosurgeons. It is mostly indicated in cases of stroke, damage to third ventricle of brain, brain hemorrhage, accidents leading to head injury, oedema around thalamus, subdural hemorrhage, and cerebrovascular accident. There is also some evidence in

thalamocortical dysrhythmia Thalamocortical dysrhythmia (TCD) is a theoretical framework in which neuroscientists try to explain the positive and negative symptoms induced by neuropsychiatric disorders like Parkinson's Disease, neurogenic pain, tinnitus, visual snow syndrom ...

Subthalamotomy

Subthalamotomy is a type of brain surgery in which the subthalamic nucleus is destroyed in attempt to help alleviate movement disorders often associated with Parkinson’s disease (PD). This surgery has been most widely researched at

Cuba Cuba, officially the Republic of Cuba, is an island country, comprising the island of Cuba (largest island), Isla de la Juventud, and List of islands of Cuba, 4,195 islands, islets and cays surrounding the main island. It is located where the ...

’s International Center for Neurological Restoration located in

Havana Havana (; ) is the capital and largest city of Cuba. The heart of La Habana Province, Havana is the country's main port and commercial center.Stix, Gary. (2003). Sustainable Surgery. ''Scientific American.'' Retrieved from http://www.scientificamerican.com/article.cfm?id=sustainable-surgery The aim of subthalamotomies is to reduce symptoms of PD and the uncontrolled movements that can occur in patients taking the drug

levodopa Levodopa, also known as L-DOPA and sold under many brand names, is a dopaminergic medication which is used in the treatment of Parkinson's disease (PD) and certain other conditions like dopamine-responsive dystonia and restless legs syndrome. ...

for a long time.Subthalamotomy. ''BootsWebMD''. Retrieved from http://www.webmd.boots.com/a-to-z-guides/parkinsons-disease-subthalamotomy

Surgical procedures

Frame for Stereotactic Thalamotomy on display at the Glenside Museum

Thalamotomy can be performed in an invasive or noninvasive manner. If performed invasively, then prior to the operation, a

neurosurgeon Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system including the brain, ...

uses

stereotactic Stereotactic surgery is a minimally invasive form of surgery, surgical intervention that makes use of a three-dimensional coordinates, coordinate system to locate small targets inside the body and to perform on them some action such as ablation, ...

technology to identify the exact part of the brain that needs treatment by putting in place a frame on the patient’s head with four pins to keep it still. The doctor then takes a detailed brain scan using

computed tomography A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

(CT scan) or

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

(MRI) to identify the precise location for operation, as well as a path through the brain to get to that specific spot. During the surgery, the patient is awake, but the area on the scalp where the surgical tools are inserted is numbed with an anesthetic. The surgeon makes a scalp incision (about 2 inches long), then inserts a hollow probe through a small hole drilled in the skull to the specific location. Different methods can be used to kill the brain cells, including circulating

liquid nitrogen Liquid nitrogen (LN2) is nitrogen in a liquid state at cryogenics, low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, mobile liquid whose vis ...

inside the probe, destroying the targeted brain tissue, or by inserting an electrode heated to near to denature the cells. Although the surgery usually requires only about a two-day hospital stay, full recovery generally takes about six weeks. Thalamotomy can be performed without incisions using ultrasound waves. The ultrasound waves are focused to the thalamus, thus cause thalamotomy through an intact skull. This procedure uses MRI guidance to localize the thalamus. The ultrasound waves cause gradual warming of the tissue until ablation occurs, seen clinically as resolution of tremor. During the procedure, the patient is awake. Thus, if any adverse effects are noted, the area of the thalamus that is treated can be adjusted before ablation. Favorable responses have so far been reported in PD patients and essential tremor patients.

Complications

Some of the patients in Cuban studies developed complications from the surgery, including severe involuntary movements, but the symptoms abated (to the point where patients could tolerate them) after three to six months. Most common complications include a risk of stroke, confusion, and speech and/or visual problems. Although risks exist with unilateral subthalamotomy, they are greatly increased with bilateral subthalamotomy.

Studies

One study followed 89 patients with PD who were treated with unilateral subthalamotomy. Sixty-eight patients were available for evaluations after 12 months, 36 after 24 months, and 25 after 36 months. The Unified Parkinson’s Disease Rating Scale motor scores improved significantly and levodopa daily doses were significantly reduced by 45, 36, and 28% at 12, 24 and 36 months after surgery. Unilateral subthalamotomy was associated with significant motor benefit contralateral to the lesion. Further work is needed to ascertain what factors led to severe, persistent

chorea Chorea, or (rarely) choreia, () is an abnormal involuntary movement disorder, characterized by quick movements of the hands or feet. It is one of a group of neurological disorders called dyskinesias. The term ''chorea'' is derived , as the move ...

ballism Hemiballismus or hemiballism is a basal ganglia syndrome resulting from damage to the subthalamic nucleus in the basal ganglia. It is a rare hyperkinetic movement disorder, that is characterized by pronounced involuntary limb movements on one ...

in a subset of patients. In an earlier study, 18 advanced PD patients received staged or simultaneous bilateral one or more subthalamotomy. One patient subsequently developed

multiple system atrophy Multiple system atrophy (MSA) is a rare neurodegenerative disorder characterized by tremors, slow movement, muscle rigidity, postural instability (collectively known as parkinsonism), autonomic dysfunction and ataxia. This is caused by progr ...

signs and was excluded from further analysis. Motor improvements compared to baseline were 58% in the off state and 63% in the on state. Daily levodopa dose was reduced by a mean of 72%, with five patients receiving none. Three patients developed severe chorea postoperatively, which improved spontaneously at 3–6 months. In a third study, microelectrode mapping (guided stereotactic surgery on the subthalamic nucleus) was performed in eight patients with PD, and the findings indicated that subthalamotomy can ameliorate the cardinal symptoms of PD, reduce the dosage of levodopa, diminish complications of the drug therapy, and improve the quality of life. Havana’s International Center for Neurological Restoration reported at the

American Neurological Association The American Neurological Association (ANA) is a professional society of academic neurologists and neuroscientists devoted to advancing the goals of academic neurology; to training and educating neurologists and other physicians in the neurologic ...

meeting in October 2002 that two years after undergoing a bilateral dorsal subthalamotomy, 17 Cuban patients improved by an average of 50% on movement tests, and they could dramatically reduce their daily ingestion of levodopa. Subthalamotomy could be a preferred option for people with PD who have trouble affording either the medication or

deep-brain stimulation Deep brain stimulation (DBS) is a type of neurostimulation therapy in which an implantable pulse generator is surgically implanted below the skin of the chest and connected by leads to the brain to deliver controlled electrical impulses. Thes ...

needed to moderate symptoms.

References

{{Central nervous system tests and procedures Neurosurgical procedures Parkinson's disease Thalamus