Spasmodic torticollis
Encyclopedia
Spasmodic torticollis is a chronic neurological movement disorder
causing the neck to involuntarily turn to the left, right, upwards, and/or downwards. The condition is also referred to as "cervical dystonia
". Both agonist and antagonist muscle contract simultaneously during dystonic movement.
Causes of the disorder are predominantly idiopathic
. A small number of patients develop the disorder as a result of another disorder or disease. Most patients first experience symptoms midlife. The most common treatment for spasmodic torticollis is the use of botulinum toxin
type A.
, neck pain, dysarthria
and tremor. Studies have shown that over 75% of patients report neck pain, and 33% to 40% experience tremor of the head.
, a disorder that is described by sustained muscle contractions causing repetitive and twisting movements, and abnormal postures in a single body region. There are two main ways to categorize spasmodic torticollis: age of onset, and cause. The disorder is categorized as early onset if the patient is diagnosed before the age of 27, and late onset thereafter. The causes are categorized as either primary (idiopathic
) or secondary (symptomatic). Spasmodic torticollis can be further categorized by the direction and rotation of head movement.
on chromosome
18p in a German family and the DYT13 locus on chromosome
1p36 in an Italian family is associated with spasmodic torticollis. The inheritance for both loci is autosomal dominant. These loci are all autosomal dominant inherited with reduced penetrance
. Although these loci have been found, it is still not clear the extent of influence the loci has on spasmodic torticollis.
Secondary spasmodic torticollis is diagnosed when any of the following are present: history of exogenous
insult of exposure, neurological abnormalities other than dystonia, abnormalities on brain imagining, particularly in the basal ganglia
.
A combination of these head positions is common; many patients experience turning and tilting actions of the head.
The pathophysiology of spasmodic torticollis is still relatively unknown. Spasmodic torticollis is considered neurochemical in nature, and does not result in structural neurodegenerative changes. Although no lesions are present in the basal ganglia
in primary spasmodic torticollis, fMRI and PET
studies have shown abnormalities of the basal ganglia
and hyper activation of the cortical areas. Studies have suggested that there is a functional imbalance in the striatal control of the globus pallidus
, specifically the substantia nigra
pars reticulate. The studies hypothesize the hyper activation of the cortical areas is due to reduced pallidal inhibition of the thalamus
, leading to over activity of the medial and prefrontal cortical areas and under activity of the primary motor cortex
during movement. It has also been suggested that the functional imbalance is due to an imbalance of neurotransmitters such as dopamine
, acetylcholine
, and gamma-aminobutyric acid
. These neurotransmitters are secreted from the basal ganglia and travel to muscle groups in the neck. An increase in neurotransmitters cause spasms to occur in the neck, resulting in spasmodic torticollis.
Studies of local field potentials have also shown an increase of 4–10 Hz oscillatory activity in the globus pallidus internus during myoclonic episodes and an increase of 5–7 Hz activity in dystonic muscles when compared to other primary dystonias. This indicates that oscillatory activity in these frequency bands may be involved in the pathophysiology of spasmodic torticollis.
This suggests that the desynchronization of the frequency range is movement related.
Sensory tricks offer only temporary and often partial relief of spasmodic torticollis. 74% of patients report only partial relief of spasmodic torticollis compared to 26% of complete relief of torticollis. The sensory trick must also be applied by the patient themselves. When the sensory trick is applied by an examiner, only 32% of patients report relief comparable to relief during self-application.
blocking agents have been used in the treatment of spasmodic torticollis. Treatment was based on the theory that there is an imbalance of the neurotransmitter dopamine in the basal ganglia. These drugs have fallen out of fashion due to various serious side effects: sedation, parkinsonism
, and tardive dyskinesia
.
Other oral medications can be used in low doses to treat early stages of spasmodic torticollis. Relief from spasmodic torticollis is higher in those patients who take anticholinergic agents when compared to other oral medications. 50% of patients who use anticholinergic agents report relief, 21% of patients report relief from clonazepam
, 11% of patients report relief from baclofen
, and 13% benzodiazepines.
Higher doses of these medications can be used for later stages of spasmodic torticollis; however, the frequency and severity of side effects associated with the medications are usually not tolerated. Side effects include dry mouth, cognitive disturbance, drowsiness, diplopia, glaucoma, urinary retention.
]
The most commonly used treatment for spasmodic torticollis is the use of botulinum toxin injection in the dystonic musculature. Botulinum toxin type A is most often used; it prevents the release of acetylcholine
from the presynaptic axon
of the motor end plate, paralyzing the dystonic muscle. By disabling the movement of the antagonist muscle, the agonist muscle is allowed to move freely. With botulinum toxin injections, patients experience relief from spasmodic torticollis for approximately 12 to 16 weeks. There are several type A preparations available worldwide; however BOTOX and Dysport are the only preparations approved by the U.S. Food and Drug Administration (FDA) for clinical use in the United States.
Some patients experience or develop immunoresistance to botulinum toxin type A and must use botulinum toxin type B. Approximately 4% to 17% of patients develop botulinum toxin type A antibodies. The only botulinum toxin type B accessible in the United States is Myobloc. Treatment using botulinum toxin type B is comparable to type A, with an increased frequency of the side effect dry mouth.
Common side effects include pain at the injection site (up to 28%), dysphagia
due to the spread to adjacent muscles (11% to 40%), dry mouth (up to 33%), fatigue (up to 17%), and weakness of the injected or adjacent muscle (up to 56%).
Deep brain stimulation
to the basal ganglia and thalamus
has recently been used as a successful treatment for tremors of patients with Parkinson's disease
. This technique is currently being implanted in patients with spasmodic torticollis in clinical trials. These patients are subjected to stimulation of the globus pallidus
internus, or the subthalamic nucleus
. The device is analogous to a pacemaker
, an external battery is placed subcutaneously with wires through the skin and enter the skull to a region of the brain. To stimulate the globus pallidus internus, microelectrodes are placed into the globus pallidus internus bilaterally. After the surgery is performed, multiple trips are required to program the settings for the stimulator. The stimulation of the globus pallidus internus disrupts the abnormal discharge pattern in the globus pallidus internus, resulting in inhibition of hyperactive cortical activity. Globus pallidus internus deep brain stimulation is the preferred surgical procedure due to the lower frequency of side effects. Advantages of deep brain stimulations include the reversibility of the procedure, and the ability to adjust settings of stimulation.
In one study, patients who have developed immunoresistance to botulinum toxin underwent globus pallidus internus deep brain stimulation showed improvement by 54.4% after three to six months.
There is a low rate of side effects for those who undergo deep brain stimulation. The most common side effect is headaches, occurring in 15% of patients, then infection (4.4%), and cognitive dysfunction (4%). Serious side effects seizure (1.2%), intracerebral hemorrhage (0.6%), intraventricular hemorrhage (0.6%), and large subdural hematoma
(0.3%).
The exact prevalence of the disorder is not known; several family and population studies show that as many as 25% of cervical dystonia patients have relatives that are undiagnosed. Studies have shown that spasmodic torticollis is not diagnosed immediately; many patients are diagnosed well after a year of seeking medical attention. A survey of 59 patients diagnosed with spasmodic torticollis show that 43% of the patients visited at least four physicians before the diagnosis was made.
There is a higher prevalence of spasmodic torticollis in females; females are 1.5 times more likely to develop spasmodic torticollis than males. The prevalence rate of spasmodic torticollis also increases with age, most patients show symptoms from ages 50–69. The average onset age of spasmodic torticollis is 41.
Movement disorder
Movement disorders include:* Akathisia * Akinesia * Associated Movements * Athetosis...
causing the neck to involuntarily turn to the left, right, upwards, and/or downwards. The condition is also referred to as "cervical dystonia
Dystonia
Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning or reaction to...
". Both agonist and antagonist muscle contract simultaneously during dystonic movement.
Causes of the disorder are predominantly idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
. A small number of patients develop the disorder as a result of another disorder or disease. Most patients first experience symptoms midlife. The most common treatment for spasmodic torticollis is the use of botulinum toxin
Botulinum toxin
Botulinum toxin is a protein produced by the bacterium Clostridium botulinum, and is considered the most powerful neurotoxin ever discovered. Botulinum toxin causes Botulism poisoning, a serious and life-threatening illness in humans and animals...
type A.
Signs and symptoms
Initial symptoms of spasmodic torticollis are usually mild. The head may turn or tilt in jerky movements, or sustain a prolonged position involuntarily. Over time, the involuntary spasm of the neck muscles will increase in frequency and strength until it reaches a plateau. Symptoms can also worsen while the patient is walking or during periods of increased stress. Other symptoms include muscle hypertrophyHypertrophy
Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It should be distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number...
, neck pain, dysarthria
Dysarthria
Dysarthria is a motor speech disorder resulting from neurological injury of the motor component of the motor-speech system and is characterized by poor articulation of phonemes...
and tremor. Studies have shown that over 75% of patients report neck pain, and 33% to 40% experience tremor of the head.
Classification
Spasmodic torticollis is a form of focal dystoniaDystonia
Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning or reaction to...
, a disorder that is described by sustained muscle contractions causing repetitive and twisting movements, and abnormal postures in a single body region. There are two main ways to categorize spasmodic torticollis: age of onset, and cause. The disorder is categorized as early onset if the patient is diagnosed before the age of 27, and late onset thereafter. The causes are categorized as either primary (idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
) or secondary (symptomatic). Spasmodic torticollis can be further categorized by the direction and rotation of head movement.
Primary
Primary spasmodic torticollis is defined as having no other abnormality other than dystonic movement and occasional tremor in the neck. This type of spasmodic torticollis is usually inherited. Studies have shown that the DYT7 locusLocus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...
on chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
18p in a German family and the DYT13 locus on chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
1p36 in an Italian family is associated with spasmodic torticollis. The inheritance for both loci is autosomal dominant. These loci are all autosomal dominant inherited with reduced penetrance
Penetrance
Penetrance in genetics is the proportion of individuals carrying a particular variant of a gene that also express an associated trait . In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation who exhibit clinical symptoms...
. Although these loci have been found, it is still not clear the extent of influence the loci has on spasmodic torticollis.
Secondary
When other conditions lead to spasmodic torticollis, it is said that the spasmodic torticollis is secondary. A variety of conditions can cause brain injury, from external factors to diseases. These conditions are listed below:- Perinatal cerebral injury
- KernicterusKernicterusKernicterus is damage to the brain centers of infants caused by increased levels of unconjugated bilirubin. This may be due to several underlying pathologic processes. Newborn babies are often polycythemic. When they break down the erythrocytes, one of the byproducts is bilirubin, which circulates...
- Cerebrovascular diseases
- Drug induced
- Central nervous systemCentral nervous systemThe central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
tumor - PeripheralPeripheralA peripheral is a device attached to a host computer, but not part of it, and is more or less dependent on the host. It expands the host's capabilities, but does not form part of the core computer architecture....
or central traumaPhysical traumaTrauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death... - Infectious or post infectious encephalopathies
- Toxins
- Metabolic
- Paraneoplastic syndromes
- Central pontine myelinolysisCentral pontine myelinolysisCentral pontine myelinolysis is neurological disease caused by severe damage of the myelin sheath of nerve cells in the brainstem, more precisely in the area termed the pons, predominately of iatrogenic etiology...
Secondary spasmodic torticollis is diagnosed when any of the following are present: history of exogenous
Exogenous
Exogenous refers to an action or object coming from outside a system. It is the opposite of endogenous, something generated from within the system....
insult of exposure, neurological abnormalities other than dystonia, abnormalities on brain imagining, particularly in the basal ganglia
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
.
Head positions
To further classify spasmodic torticollis, one can note the position of the head.- Torticollis is the horizontal turning (rotational collis) of the head, and uses the ipsilateral spleniusSplenius musclesThe splenius muscles are:*Splenius capitis muscle*Splenius cervicis muscle...
, and contralateral sternocleidomastoidSternocleidomastoid muscleIn human anatomy, the sternocleidomastoid muscle , also known as sternomastoid and commonly abbreviated as SCM, is a paired muscle in the superficial layers of the anterior portion of the neck...
muscles. This is the "chin-to-shoulder" version. - Laterocollis is the tilting of the head from side to side. This is the "ear-to-shoulder" version. This involves many more muscles: ipsilateral sternocleidomastoid, ipsilateral splenius, ipsilateral scalene complex, ipsilateral levator scapulae, and ipsilateral posterior paravertebrals.
- The flexion of the neck (head tilts forwards) is anterocollis. This is the "chin-to-chest" version and is the most difficult version to address. This movement utilizes the bilateral sternocleidomastoid, bilateral scalene complex, bilateral submental complex.
- Retrocollis is the extension of the neck (head tilts back) and uses the following muscles for movement: bilateral splenius, bilateral upper trapezius, bilateral deep posterior paravertebrals. This is the "chin-in-the-air" version.
A combination of these head positions is common; many patients experience turning and tilting actions of the head.
Diagnosis
The most commonly used scale to rate the severity of spasmodic torticollis is the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). It has been shown that this rating system has widespread acceptance for use in clinical trials, and has been shown to have “good interobserver reliability.” There are three scales in the TWSTRS: torticollis severity scale, disability scale, and pain scale. These scales are used to represent the severity, the pain, and the general lifestyle of spasmodic torticollis.Pathophysiology
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
in primary spasmodic torticollis, fMRI and PET
Positron emission tomography
Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...
studies have shown abnormalities of the basal ganglia
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
and hyper activation of the cortical areas. Studies have suggested that there is a functional imbalance in the striatal control of the globus pallidus
Globus pallidus
The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...
, specifically the substantia nigra
Substantia nigra
The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...
pars reticulate. The studies hypothesize the hyper activation of the cortical areas is due to reduced pallidal inhibition of the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, leading to over activity of the medial and prefrontal cortical areas and under activity of the primary motor cortex
Motor cortex
Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions.-Anatomy of the motor cortex :The motor cortex can be divided into four main parts:...
during movement. It has also been suggested that the functional imbalance is due to an imbalance of neurotransmitters such as dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
, acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
, and gamma-aminobutyric acid
Gamma-aminobutyric acid
γ-Aminobutyric acid is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays a role in regulating neuronal excitability throughout the nervous system...
. These neurotransmitters are secreted from the basal ganglia and travel to muscle groups in the neck. An increase in neurotransmitters cause spasms to occur in the neck, resulting in spasmodic torticollis.
Studies of local field potentials have also shown an increase of 4–10 Hz oscillatory activity in the globus pallidus internus during myoclonic episodes and an increase of 5–7 Hz activity in dystonic muscles when compared to other primary dystonias. This indicates that oscillatory activity in these frequency bands may be involved in the pathophysiology of spasmodic torticollis.
Treatment
There are several treatments for spasmodic torticollis, the most commonly used being botulinum toxin injections in the dystonic muscle of the neck. Other treatments include sensory trick, oral medications, and deep brain stimulation. Combinations of these treatments have been used to control spasmodic torticollis. In addition, selective surgical denervation of nerves triggering muscle contractions may offer relief from spasms, pain, and limit damage to the spine as a result of torqued posture. Spinal fibrosis (i.e., locking of spinal facets due to muscular contortion resulting in fused vertebrates) may occur rapidly. Therefore, it is important to seriously evaluate the option of surgical denervation as early as possible.This suggests that the desynchronization of the frequency range is movement related.
Sensory tricks offer only temporary and often partial relief of spasmodic torticollis. 74% of patients report only partial relief of spasmodic torticollis compared to 26% of complete relief of torticollis. The sensory trick must also be applied by the patient themselves. When the sensory trick is applied by an examiner, only 32% of patients report relief comparable to relief during self-application.
Oral medications
In the past, dopamineDopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
blocking agents have been used in the treatment of spasmodic torticollis. Treatment was based on the theory that there is an imbalance of the neurotransmitter dopamine in the basal ganglia. These drugs have fallen out of fashion due to various serious side effects: sedation, parkinsonism
Parkinsonism
Parkinsonism is a neurological syndrome characterized by tremor, hypokinesia, rigidity, and postural instability. The underlying causes of parkinsonism are numerous, and diagnosis can be complex...
, and tardive dyskinesia
Tardive dyskinesia
Tardive dyskinesia is a difficult-to-treat form of dyskinesia that can be tardive...
.
Other oral medications can be used in low doses to treat early stages of spasmodic torticollis. Relief from spasmodic torticollis is higher in those patients who take anticholinergic agents when compared to other oral medications. 50% of patients who use anticholinergic agents report relief, 21% of patients report relief from clonazepam
Clonazepam
Clonazepamis a benzodiazepine drug having anxiolytic, anticonvulsant, muscle relaxant, and hypnotic properties. It is marketed by Roche under the trade name Klonopin in the United States and Rivotril in Australia, Brazil, Canada and Europe...
, 11% of patients report relief from baclofen
Baclofen
Baclofen is a derivative of gamma-aminobutyric acid . It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism....
, and 13% benzodiazepines.
Higher doses of these medications can be used for later stages of spasmodic torticollis; however, the frequency and severity of side effects associated with the medications are usually not tolerated. Side effects include dry mouth, cognitive disturbance, drowsiness, diplopia, glaucoma, urinary retention.
Botulinum toxin
The most commonly used treatment for spasmodic torticollis is the use of botulinum toxin injection in the dystonic musculature. Botulinum toxin type A is most often used; it prevents the release of acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
from the presynaptic axon
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
of the motor end plate, paralyzing the dystonic muscle. By disabling the movement of the antagonist muscle, the agonist muscle is allowed to move freely. With botulinum toxin injections, patients experience relief from spasmodic torticollis for approximately 12 to 16 weeks. There are several type A preparations available worldwide; however BOTOX and Dysport are the only preparations approved by the U.S. Food and Drug Administration (FDA) for clinical use in the United States.
Some patients experience or develop immunoresistance to botulinum toxin type A and must use botulinum toxin type B. Approximately 4% to 17% of patients develop botulinum toxin type A antibodies. The only botulinum toxin type B accessible in the United States is Myobloc. Treatment using botulinum toxin type B is comparable to type A, with an increased frequency of the side effect dry mouth.
Common side effects include pain at the injection site (up to 28%), dysphagia
Dysphagia
Dysphagia is the medical term for the symptom of difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, the term is sometimes used as a condition in its own right. Sufferers are sometimes unaware of their dysphagia....
due to the spread to adjacent muscles (11% to 40%), dry mouth (up to 33%), fatigue (up to 17%), and weakness of the injected or adjacent muscle (up to 56%).
Deep brain stimulation
Deep brain stimulation
Deep brain stimulation is a surgical treatment involving the implantation of a medical device called a brain pacemaker, which sends electrical impulses to specific parts of the brain...
to the basal ganglia and thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
has recently been used as a successful treatment for tremors of patients with Parkinson's disease
Parkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
. This technique is currently being implanted in patients with spasmodic torticollis in clinical trials. These patients are subjected to stimulation of the globus pallidus
Globus pallidus
The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...
internus, or the subthalamic nucleus
Subthalamic nucleus
The subthalamic nucleus is a small lens-shaped nucleus in the brain where it is, from a functional point of view, part of the basal ganglia system. Anatomically, it is the major part of subthalamus. As suggested by its name, the subthalamic nucleus is located ventral to the thalamus. It is also...
. The device is analogous to a pacemaker
Pacemaker
An artificial pacemaker is a medical device that uses electrical impulses to regulate the beating of the heart.Pacemaker may also refer to:-Medicine:...
, an external battery is placed subcutaneously with wires through the skin and enter the skull to a region of the brain. To stimulate the globus pallidus internus, microelectrodes are placed into the globus pallidus internus bilaterally. After the surgery is performed, multiple trips are required to program the settings for the stimulator. The stimulation of the globus pallidus internus disrupts the abnormal discharge pattern in the globus pallidus internus, resulting in inhibition of hyperactive cortical activity. Globus pallidus internus deep brain stimulation is the preferred surgical procedure due to the lower frequency of side effects. Advantages of deep brain stimulations include the reversibility of the procedure, and the ability to adjust settings of stimulation.
In one study, patients who have developed immunoresistance to botulinum toxin underwent globus pallidus internus deep brain stimulation showed improvement by 54.4% after three to six months.
There is a low rate of side effects for those who undergo deep brain stimulation. The most common side effect is headaches, occurring in 15% of patients, then infection (4.4%), and cognitive dysfunction (4%). Serious side effects seizure (1.2%), intracerebral hemorrhage (0.6%), intraventricular hemorrhage (0.6%), and large subdural hematoma
Subdural hematoma
A subdural hematoma or subdural haematoma , also known as a subdural haemorrhage , is a type of haematoma, a form of traumatic brain injury. Blood gathers within the outermost meningeal layer, between the dura mater, which adheres to the skull, and the arachnoid mater, which envelops the brain...
(0.3%).
Epidemiology
Spasmodic torticollis is one of the most common forms of dystonia seen in neurology clinics, occurring in approximately 0.390% of the United States population in 2007 (390 per 100,000). Worldwide, it has been reported that the incidence rate of spasmodic torticollis is at least 1.2 per 100,000 person years, and a prevalence rate of 57 per 1 million.The exact prevalence of the disorder is not known; several family and population studies show that as many as 25% of cervical dystonia patients have relatives that are undiagnosed. Studies have shown that spasmodic torticollis is not diagnosed immediately; many patients are diagnosed well after a year of seeking medical attention. A survey of 59 patients diagnosed with spasmodic torticollis show that 43% of the patients visited at least four physicians before the diagnosis was made.
There is a higher prevalence of spasmodic torticollis in females; females are 1.5 times more likely to develop spasmodic torticollis than males. The prevalence rate of spasmodic torticollis also increases with age, most patients show symptoms from ages 50–69. The average onset age of spasmodic torticollis is 41.