Pallidotomy is a

neurosurgical 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, s ...

procedure. It is used to treat

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 ...

and some other conditions, often as an alternative to

deep brain stimulation Deep brain stimulation (DBS) is a type of neurostimulation therapy in which an implantable pulse generator is stereotactic surgery, surgically implanted subcutaneous tissue, below the skin of the chest and connected by Lead (electronics), leads ...

. It involves placing a tiny electrical probe in the

globus pallidus The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a major component of the Cerebral cortex, subcortical basal ganglia in the brain. It consists of two adjacent segments, one external (or lateral), known in rodents simpl ...

, one of the

basal ganglia The basal ganglia (BG) or basal nuclei are a group of subcortical Nucleus (neuroanatomy), nuclei found in the brains of vertebrates. In humans and other primates, differences exist, primarily in the division of the globus pallidus into externa ...

of the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

, to damage it. Unilateral pallidotomy can cause side effects including problems with language learning, visuospatial constructional ability, and

executive functions In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that support goal-directed behavior, by regulating thoughts and actions thro ...

. Bilateral pallidotomy is not effective, with many severe side effects.

Uses

Rationale

The

internal globus pallidus The internal globus pallidus (GPi or medial globus pallidus) is one of the two subcortical nuclei that provides inhibitory output in the basal ganglia, the other being the substantia nigra pars reticulata. Together with the external globus pallid ...

can be regarded as an "output structure" of the

. It processes input from

nucleus accumbens The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for ' nucleus adjacent to the septum') is a region in the basal forebrain rostral to the preoptic area of the hypo ...

and the

striatum The striatum (: striata) or corpus striatum is a cluster of interconnected nuclei that make up the largest structure of the subcortical basal ganglia. The striatum is a critical component of the motor and reward systems; receives glutamat ...

, and sends input to the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...

via 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 ...

. It is critical for the functioning of the

Parkinson's disease

Pallidotomy is an alternative to

for the treatment of the involuntary movements known as

dyskinesia Dyskinesia refers to a category of movement disorders that are characterized by involuntary muscle movements, including movements similar to tics or chorea and diminished voluntary movements. Dyskinesia can be anything from a slight tremor of t ...

s which can become a problem in people with

after long-term treatment with

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. ...

— a condition known as

levodopa-induced dyskinesia Levodopa-induced dyskinesia (LID) is a form of dyskinesia associated with levodopa (l-DOPA), used to treat Parkinson's disease. It often involves hyperkinetic movements, including chorea, dystonia, and athetosis. In the context of Parkinson's di ...

. Whilst it used to be used a primary treatment for Parkinson's disease, it has been mainly replaced by levodopa.

Other conditions

Pallidotomy may sometimes used to treat difficult cases of

essential tremor Essential tremor (ET), also called benign tremor, familial tremor, and idiopathic tremor, is a medical condition characterized by involuntary rhythmic contractions and relaxations ( oscillations or twitching movements) of certain muscle groups i ...

as an alternative to deep brain stimulation. It may also be used for

dystonia Dystonia is a neurology, neurological Hyperkinesia, hyperkinetic Movement disorders, movement disorder in which sustained or repetitive muscle contractions occur involuntarily, resulting in twisting and repetitive movements or abnormal fixed po ...

, and

hemiballismus 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 ...

Complications

Unilateral __NOTOC__ Unilateralism is any doctrine or agenda that supports one-sided action. Such action may be in disregard for other parties, or as an expression of a commitment toward a direction which other parties may find disagreeable. As a word, ''un ...

posteroventral pallidotomy can be effective at reducing Parkinsonism. However, it is associated with impaired language learning (if performed on the dominant hemisphere) or impaired visuospatial constructional ability (if performed on the non-dominant hemisphere). It can also impair

Bilateral Bilateral may refer to any concept including two sides, in particular: *Bilateria, bilateral animals *Bilateralism, the political and cultural relations between two states *Bilateral, occurring on both sides of an organism ( Anatomical terms of l ...

pallidotomy will not reduce Parkisonistic symptoms. It will cause severe

apathy Apathy, also referred to as indifference, is a lack of feeling, emotion, interest, or concern about something. It is a state of indifference, or the suppression of emotions such as concern, excitement, motivation, or passion. An apathetic i ...

and depression, along with slurred, unintelligible speech, drooling, and

pseudobulbar palsy Pseudobulbar palsy is a medical condition characterized by the inability to control facial movements (such as chewing and speaking) and caused by a variety of neurological disorders. Patients experience difficulty chewing and swallowing, have i ...

. The surgery itself can cause complications. Damage to a blood vessel may cause

intracranial haemorrhage Intracranial hemorrhage (ICH) refers to any form of bleeding within the skull. It can result from trauma, vascular abnormalities, hypertension, or other medical conditions. ICH is broadly categorized into several subtypes based on the location ...

. Damage to the

optic tract In neuroanatomy, the optic tract () is a part of the visual system in the brain. It is a continuation of the optic nerve that relays information from the optic chiasm to the ipsilateral lateral geniculate nucleus (LGN), pretectal nuclei, and su ...

can cause a permanent vision problem. Pressure on brain tissue can induce a

seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...

Technique

Pallidotomy involves placing a tiny electrical probe in the globus pallidus, one of the

of the

. A

craniotomy A craniotomy is a surgery, surgical operation in which a bone flap is temporarily removed from the Human skull, skull to access the Human brain, brain. Craniotomies are often critical operations, performed on patients who are suffering from brain ...

(temporary hole in the skull) needs to be created. The probe is guided based on

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, ...

information, and sometimes

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 ...

. The globus pallidus is heated for a short time to destroy a small area of

brain cells Brain cells make up the functional tissue of the brain. The rest of the brain tissue is the structural stroma that includes connective tissue such as the meninges, blood vessels, and ducts. The two main types of cells in the brain are neurons, ...

History

Pallidotomy has been used to treat

since at least the 1950s. Older techniques involved occluding the

anterior choroidal artery The anterior choroidal artery is a bilaterally paired artery of the brain. It is typically a branch of the internal carotid artery which supplies the choroid plexus of lateral ventricle and third ventricle as well as numerous structures of the br ...

, with lower success rates and more side effects.

References

{{Central nervous system tests and procedures Neurosurgical procedures