There is physiological intracranial calcification in about 0,3-1,5% of individuals. Fahr's disease is a rare, genetically dominant, inherited neurological disorder characterized by abnormal deposits of calcium, primarily in the basal ganglia.

Basal ganglia disease is a group of physical s that occur when the group of nuclei in the brain known as the basal ganglia fail to properly suppress unwanted movements or to properly prime upper motor neuron circuits to initiate motor function. Research indicates that increased output of the basal ganglia inhibits thalamocortical projection neurons. Proper activation or deactivation of these neurons is an integral component for proper movement. If something causes too much basal ganglia output, then the thalamocortical projection neurons become too inhibited and one cannot initiate voluntary movement. These disorders are known as hypokinetic disorders. However, a disorder leading to abnormally low output of the basal ganglia leads to relatively no inhibition of the thalamocortical projection neurons. This situation leads to an inability to suppress unwanted movements. These disorders are known as hyperkinetic disorders. Currently, reasons for abnormal increases or decreases of basal ganglia output are poorly understood. One possible factor could be the natural accumulation of iron in the basal ganglia, causing neurodegeneration due to its involvement in toxic free-radical reactions. Though motor disorders are the most common associated with the basal ganglia, recent research shows that basal ganglia disorders can lead to other dysfunctions such as obsessive compulsive disorder (OCD) and Tourette syndrome.

Clinical presentation of CBD usually does not occur until age 60, with the earliest recorded diagnosis and subsequent postmortem verification being age 28. Although men and women present with the disease, some analysis has shown a predominant appearance of CBD in women. Current calculations suggest that the prevalence of CBD is approximately 4.9 to 7.3 per 100,000 people. The prognosis for an individual diagnosed with CBD is death within approximately eight years, although some patients have been diagnosed over 17 years ago (2017) and are still in relatively good standing, but with serious debilitation such as dysphagia, and overall limb rigidity. The partial (or total) use of a feeding tube may be necessary and will help prevent aspiration pneumonia, primary cause of death in CBD. Incontinence is common, as patients often can't express their need to go, due to eventual loss of speech. Therefore, proper hygiene is mandatory to prevent urinary tract infections.

Surgery, such as the denervation of selected muscles, may also provide some relief; however, the destruction of nerves in the limbs or brain is not reversible and should be considered only in the most extreme cases. Recently, the procedure of deep brain stimulation (DBS) has proven successful in a number of cases of severe generalised dystonia. DBS as treatment for medication-refractory dystonia, on the other hand, may increase the risk of suicide in patients. However, reference data of patients without DBS therapy are lacking.

Mobility issues associated with falls and freezing of gait have a devastating impact in the lives of PD patients. Fear of falling in itself can have an incapacitating effect in PD patients and can result in social seclusion leaving patients largely isolated leading to depression. Immobility can also lead to osteoporosis which in-turn facilitates future fracture development. This then becomes a vicious circle with falls leading to immobility and immobility facilitating future falls. Hip fractures from falls are the most common form of fracture among PD patients. Fractures increase treatment costs associated with health care expenditures in PD. Also, when gait is affected it often heralds the onset of Lewy body dementia.

In examining the causes of hemiballismus, it is important to remember that this disorder is extremely rare. While hemiballismus can result from the following list, just because a patient suffers from one of these disorders does not mean they will also suffer from hemiballismus.

Stroke

Hemisballismus as a result of stroke occurs in only about 0.45 cases per hundred thousand stroke victims. Even at such a small rate, stroke is by far the most common cause of hemiballismus. A stroke causes tissue to die due to a lack of oxygen resulting from an impaired blood supply. In the basal ganglia, this can result in the death of tissue that helps to control movement. As a result, the brain is left with damaged tissue that sends damaged signals to the skeletal muscles in the body. The result is occasionally a patient with hemiballismus.

Traumatic Brain Injury

Hemiballismus can also occur as a result of a traumatic brain injury. There are cases in which victims of assault or other forms of violence have developed hemiballismus. Through these acts of violence, the victim’s brain has been damaged and the hemiballistic movements have developed.

Amyotrophic Lateral Sclerosis

This disease causes neuronal loss and gliosis, which can include the subthalamic nucleus and other areas of the brain. Essentially any disorder that causes some form of neuronal loss or gliosis in the basal ganglia has the potential to cause hemiballismus.

Nonketotic Hyperglycemia

Patients with nonketotic hyperglycemia can develop hemiballismus as a complication to the disease through the development of a subthalamic nucleus lesion. This is the second most common reported cause of hemiballismus. It can be found primarily in the elderly and many of the reported cases have come from East Asian origin, which suggests that there may be some genetic disposition to development of hemiballismus as a result of hyperglycemia. Hemiballistic movements appear when blood glucose levels get too high and then subside once glucose levels return to normal. This time scale for this is usually several hours. In patients with this type of hemiballismus, imaging reveals abnormalities in the putamen contralateral to the movements as well as the globus pallidus and caudate nucleus. While the hyperglycemia itself is not the cause of the hemiballistic movements, it has been suggested that petechial hemorrhage or a decreased production of GABA and acetylcholine could result secondary to the hyperglycemia. One of these issues could be responsible for the hemiballistic movements.

Neoplasms

A neoplasm is an abnormal growth of cells. Cases have shown that if this occurs somewhere in the basal ganglia, hemiballismus can result.

Vascular malformations

Vascular malformations can cause abnormal blood flow to areas of the brain. If too little blood is delivered to the basal ganglia, a stroke can occur.

Tuberculomas

This is another form of tumor that can result in the brain as a result of a tuberculous meningitis infection. This type of tumor can also damage parts of the basal ganglia, sometimes resulting in hemiballismus.

Demyelinating plaques

Demyelinating plaques attack the myelin sheaths on neurons. This decreases the conduction velocity of the neurons, making the signals received by the basal ganglia garbled and incomplete. This disorganized signal can also cause the chaotic movements characterized by hemiballismus.

Complications from HIV infection

Patients with HIV often have complications that arise along with AIDS. Hypoglycemia due to pentamidine use in patients with AIDS has been known to cause hemiballismus. In some patients, hemiballismus has been the only visible symptom to alert the physician that the patients may have AIDS. It is typically a result of a secondary infection that occurs due to the compromised immune system and the most common infection causing hemiballismus is cerebral toxoplasmosis. Most of the lesions that result from this infection are found in the basal ganglia. As long as the diagnosis is not missed, this type of hemiballismus can be treated just as well as in patients without HIV.

Hypokinesia refers to decreased bodily movement. One of the two categories of movement disorders, hypokinesia is characterized by a partial or complete loss of muscle movement due to a disruption in the basal ganglia. Patients with hypokinetic disorders like Parkinson's disease experience muscle rigidity and an inability to produce movement. It is also associated with mental health disorders and prolonged inactivity due to illness, amongst other diseases.

The other category of movement disorder resulting from damage to the basal ganglia, hyperkinesia, features an exaggeration of unwanted motion, like twitching or writhing in Huntington's disease or Tourette syndrome.

In the past, the prognosis for patients with this disease had been very poor; with many patients suffering from severe disability or death. Now, patients are responding remarkably well to current treatments and the majority of patients go into spontaneous remission. For those that do not go into remission, the symptoms of hemiballismus can generally be very well controlled with medication.

Due to the rarity of this disorder, scientists know very little about the details of hemiballismus. There are still many unanswered questions such as:

•There appears to be a discrepancy between this disorder in humans and animals that has yet to be explained.

•Hemiballismus can also be induced by damage to other areas of the basal ganglia besides the subthalamic nucleus. Why is this? Research is being done in these areas in order to give scientists and clinicians a better model for this disease that will ultimately lead to better diagnosis and treatment of this disorder.

•Research is also being done on why certain treatments seem to help hemiballistic patients when they should seemingly do more harm. An example of this is why lesioning the globus pallidus seems to reduce hemiballistic movements.

•Why does blocking dopamine help reduce patients’ symptoms?

Corticobasal degeneration (CBD) or corticobasal ganglionic degeneration (CBGD) is a rare, progressive neurodegenerative disease involving the cerebral cortex and the basal ganglia. CBD symptoms typically begin in people from 50–70 years of age, and the average disease duration is six years. It is characterized by marked disorders in movement and cognitive dysfunction, and is classified as one of the Parkinson plus syndromes. Clinical diagnosis is difficult, as symptoms of CBD are often similar to those of other disorders, such as Parkinson's disease (PD), progressive supranuclear palsy (PSP), and dementia with Lewy bodies (DLB). Due to the various clinical presentations associated with CBD, a final diagnosis can only be made upon neuropathologic examination.

Movement disorders are clinical syndromes with either an excess of movement or a paucity of voluntary and involuntary movements, unrelated to weakness or spasticity. Movement disorders are synonymous with basal ganglia or extrapyramidal diseases. Movement disorders are conventionally divided into two major categories- "hyperkinetic" and "hypokinetic".

Hyperkinetic movement disorders refer to dyskinesia, or excessive, often repetitive, involuntary movements that intrude upon the normal flow of motor activity.

Hypokinetic movement disorders refer to akinesia (lack of movement), hypokinesia (reduced amplitude of movements), bradykinesia (slow movement) and rigidity. In primary movement disorders, the abnormal movement is the primary manifestation of the disorder. In secondary movement disorders, the abnormal movement is a manifestation of another systemic or neurological disorder.

Treatment depends upon the underlying disorder. Movement disorders have been known to be associated with a variety of autoimmune diseases.

Survival rates for those diagnosed with typical PKAN is 11.18 years with a standard deviation of 7.8 years.

All PD associated subtypes have genetic contributions and are likely to run in a families genetic history due to dominant allele mutations. Mutations of identified genes have been leading areas of research in the study and treatment of paroxysmal dyskinesia. PKD, PNKD, and PED are classified as separate subtypes because they all have different presentations of symptoms, but also, because they are believed to have different pathologies.

Interestingly, studies on diseases that are similar in nature to PD have revealed insights into the causes of movement disorders. Hypnogenic paroxysmal dyskinesia is a form of epilepsy affecting the frontal lobe. Single genes have been identified on chromosomes 15, 20, and 21, which contribute to the pathology of these epilepsy disorders. Utilizing new knowledge about pathologies of related and similar disease can shed insight on the causal relationships in paroxysmal dyskinesia.

Hyperkinesia, also known as hyperkinesis, refers to an increase in muscular activity that can result in excessive abnormal movements, excessive normal movements, or a combination of both. The word hyperkinesis comes from the Greek "hyper", meaning "increased," and "kinein", meaning "to move." Hyperkinesia is a state of excessive restlessness which is featured in a large variety of disorders that affect the ability to control motor movement, such as Huntington's disease. It is the opposite of hypokinesia, which refers to decreased bodily movement, as commonly manifested in Parkinson's disease. Many hyperkinetic movements are the result of improper regulation of the basal ganglia-thalamocortical circuitry. Overactivity of a direct pathway combined with decreased activity of an indirect pathway results in activation of thalamic neurons and excitation of cortical neurons, resulting in increased motor output. Often, hyperkinesia is paired with hypotonia, a decrease in muscle tone. Many hyperkinetic disorders are psychological in nature and are typically prominent in childhood. Depending on the specific type of hyperkinetic movement, there are different treatment options available to minimize the symptoms, including different medical and surgical therapies.

Chorea is another condition which results from damage to the basal ganglia. Similar to athetosis, it results from mutations affecting the pallidum inhibition of the thalamus as well as increased dopaminergic activity at the level of the striatum. Considering the etiology of both disorders are fairly similar, it comes as no surprise that chorea and athetosis can and usually do occur together in a condition called choreoathetosis.

Paroxysmal Dyskinesia is not a fatal disease. Life can be extremely difficult with this disease depending on the severity. The prognosis of PD is extremely difficult to determine because the disease varies from person to person. The attacks for PKD can be reduced and managed with proper anticonvulsants, but there is no particular end in sight for any of the PD diseases. PKD has been described to cease for some patients after the age of 20, and two patients have reported to have a family history of the disease where PKD went into complete remission after the age of 23. With PNKD and PED, at this time, there is no proper way to determine an accurate prognosis.

Athetosis is a commonly occurring symptom in the disease cerebral palsy. Of all people with the disease, between 16% and 25% of them actually exhibit the symptom of athetosis. A component of this is the finding that most often the symptoms that involve athetosis occur as a part of choreoathetosis as opposed to athetosis alone.

It is also noteworthy that the presence of athetosis in cerebral palsy (as well as other conditions) causes a significant increase in a person’s basal resting metabolic rate. It has been observed that those who have cerebral palsy with athetosis require approximately 500 more Calories per day than their non-cerebral palsy non-athetoid counterpart.

Paroxysmal kinesigenic dyskinesia has been shown to be inherited in an autosomal dominant fashion. In 2011, the PRRT2 gene on chromosome 16 was identified as the cause of the disease. The researchers looked at the genetics of eight families with strong histories of PKD. They employed whole genome sequencing, along with Sanger sequencing to identify the gene that was mutated in these families. The mutations in this gene included a nonsense mutation identified in the genome of one family and an insertion mutation identified in the genome of another family. The researchers then confirmed this gene as the cause of PKD when it was not mutated in the genome of 1000 control patients. Researchers found PRRT2 mutations in 10 of 29 sporadic cases affected with PKD, thus suggests PRRT2 is the gene mutated in a subset of PKD and PKD is genetically heterogeneous. The mechanism of how PRRT2 causes PKD still requires further investigation. However, researchers suggest it may have to do with PRRT2's expression in the basal ganglia, and the expression of an associated protein, SNAP25, in the basal ganglia as well.

Motor disorders are disorders of the nervous system that cause abnormal and involuntary movements. They can result from damage to the motor system.

Motor disorders are defined in the fifth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5) – published in 2013 to replace the fourth text revision (DSM-IV-TR) – as a new sub-category of neurodevelopmental disorders. The DSM-5 motor disorders include developmental coordination disorder, stereotypic movement disorder, and the tic disorders including Tourette syndrome.

There are many potential causes of dysarthria. They include toxic, metabolic, degenerative diseases, traumatic brain injury, or thrombotic or embolic stroke.

Degenerative diseases include parkinsonism, amyotrophic lateral sclerosis (ALS), multiple sclerosis, Huntington's disease, Niemann-Pick disease, and Friedreich ataxia.

Toxic and metabolic conditions include: Wilson's disease, hypoxic encephalopathy such as in drowning, and central pontine myelinolysis.

These result in lesions to key areas of the brain involved in planning, executing, or regulating motor operations in skeletal muscles (i.e. muscles of the limbs), including muscles of the head and neck (dysfunction of which characterises dysarthria). These can result in dysfunction, or failure of: the motor or somatosensory cortex of the brain, corticobulbar pathways, the cerebellum, basal nuclei (consisting of the putamen, globus pallidus, caudate nucleus, substantia nigra etc.), brainstem (from which the cranial nerves originate), or the neuro-muscular junction (in diseases such as myasthenia gravis) which block the nervous system's ability to activate motor units and effect correct range and strength of movements.

Causes:

- Brain tumor

- Cerebral palsy

- Guillain–Barré syndrome

- Hypothermia

- Lyme disease

- Stroke

- Intracranial hypertension (formerly known as pseudotumor cerebri)

- Tay-Sachs, and late onset Tay-Sachs (LOTS), disease

Blocq's disease was first considered by Paul Blocq (1860–1896), who described this phenomenon as the loss of memory of specialized movements causing the inability to maintain an upright posture, despite normal function of the legs in the bed. The patient is able to stand up, but as soon as the feet are on the ground, the patient cannot hold himself upright nor walk; however when lying down, the subject conserved the integrity of muscular force and the precision of movements of the lower limbs. The motivation of this study came when a fellow student Georges Marinesco (1864) and Paul published a case of parkinsonian tremor (1893) due to a tumor located in the substantia nigra.

In the third paper published by Paul Blocq, he was trying to determine the neurophysiology behind this disease by relating the cerebral cortex (the decision making) and the spinal cord (the decision executer). His hypothesis was that there would exist an inhibitory influence which exerted and influenced the cortical or spinal centers for standing and walking.

The exact cause of palilalia is unknown.

Palilalia also occurs in a variety of neurodegenerative disorders, occurring most commonly in Tourette syndrome, Alzheimer's disease, and progressive supranuclear palsy. Such degradation can occur in the substantia nigra where decreased dopamine production results in a loss of function. It can also occur in a variety of genetic disorders including Fragile X syndrome, Prader-Willi syndrome, Asperger's syndrome, autism, and the speaker has no difficulty initiating speech.

In a study by Joo et al., the researchers performed interictal studies, meaning they scanned the patient's brain between attacks to find an underlying abnormality, rather than ictal scans, which look at the abnormalities that present themselves during an attack. The researchers found interictally decreased cerebral blood flow in the posterior parts of the bilateral caudate nucleus. However, the literature does state that although this could be a cause of PKD, it could also be a result of PKD. Another SPECT study showed an increase in the cerebral blood flow in the left posterior thalamus in a PKD patient during an attack. The researchers also subtracted the ictal from the postictal scans, and saw increased blood flow in the thalamus. They ultimately suggested that hyperactive blood flow in this area could be causing the pathophysiology of PKD. This study, however, was only performed on one patient, and would need to be replicated many more times in order to be generalized to the population of PKD patients. Other SPECT studies have been cited showing hyperactivity in the basal ganglia.

Treatment of tics present in conditions such as Tourette’s syndrome begins with patient, relative, teacher and peer education about the presentation of the tics. Sometimes, pharmacological treatment is unnecessary and tics can be reduced by behavioral therapy such as habit-reversal therapy and/or counseling. Often this route of treatment is difficult because it depends most heavily on patient compliance. Once pharmacological treatment is deemed most appropriate, lowest effective doses should be given first with gradual increases. The most effective drugs belong to the neuroleptic variety such as monoamine-depleting drugs and dopamine receptor-blocking drugs. Of the monoamine-depleting drugs, tetrabenazine is most powerful against tics and results in fewest side effects. A non-neuroleptic drug found to be safe and effective in treating tics is topiramate. Botulinum toxin injection in affected muscles can successfully treat tics; involuntary movements and vocalizations can be reduced, as well as life-threatening tics that have the potential of causing compressive myelopathy or radiculopathy. Surgical treatment for disabling Tourette’s syndrome has been proven effective in cases presenting with self-injury. Deep Brain Stimulation surgery targeting the globus pallidus, thalamus and other areas of the brain may be effective in treating involuntary and possibly life-threatening tics.

Though it is often most associated with Parkinson's disease, hypokinesia can be present in a wide variety of other conditions.