The prognosis for those with spastic muscles depends on multiple factors, including the severity of the spasticity and the associated movement disorder, access to specialised and intensive management, and ability of the affected individual to maintain the management plan (particularly an exercise program). Most people with a significant UMN lesion will have ongoing impairment, but most of these will be able to make progress. The most important factor to indicate ability to progress is seeing improvement, but improvement in many spastic movement disorders may not be seen until the affected individual receives help from a specialised team or health professional.

Doublecortin positive cells, Similar to stem cells, are extremely adaptable and, when extracted from a brain, cultured and then re-injected in a lesioned area of the same brain, they can help repair and rebuild it. The treatment using them would take some time to be available for general public use, as it has to clear regulations and trials.

The muscle spasticity can cause gait patterns to be awkward and jerky. The constant spastic state of the muscle can lead to bone and tendon deformation, further complicating the patient's mobility. Many patients with spastic hemiplegia are subjected to canes, walkers and even wheelchairs. Due to the decrease in weight bearing, patients are at a higher risk of developing osteoporosis. An unhealthy weight can further complicate mobility. Patients with spastic hemiplegia are a high risk for experiencing seizures. Oromotor dysfunction puts patients at risk for aspiration pneumonia. Visual field deficits can cause impaired two-point discrimination. Many patients experience the loss of sensation in the arms and legs on the affected side of the body. Nutrition is essential for the proper growth and development for a child with spastic hemiplegia.

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.

Hemiplegia is not a progressive disorder, except in progressive conditions like a growing brain tumour. Once the injury has occurred, the symptoms should not worsen. However, because of lack of mobility, other complications can occur. Complications may include muscle and joint stiffness, loss of aerobic fitness, muscle spasms, bed sores, pressure ulcers and blood clots.

Sudden recovery from hemiplegia is very rare. Many of the individuals will have limited recovery, but the majority will improve from intensive, specialised rehabilitation. Potential to progress may differ in cerebral palsy, compared to adult acquired brain injury. It is vital to integrate the hemiplegic child into society and encourage them in their daily living activities. With time, some individuals may make remarkable progress.

The incidence of cerebral palsy has increased in the past 40 years. It has been estimated that in the United States cerebral palsy occurs in 4 out every 1000 births. Of these births about 20–30% of them have spastic hemiplegia. Spasticity overall, is the more common type of cerebral palsy, whereas as non-spastic cerebral palsy is less common. Studies show that spastic type cerebral palsy is on the rise, and the occurrence of diplegia type is decreasing. The prevalence of cerebral palsy is higher in areas of low socioeconomic status. This could potentially be because cerebral palsy incidence increases as birth weight decreases.

Recent research indicates that the biomolecule taurine may be effective for hypertonia, perhaps through its benzodiazepine-like modulation of the inhibitory neurotransmitter GABA or the neuromuscular effects of increasing intracellular calcium levels.

Treatment should be based on assessment by the relevant health professionals. For muscles with mild-to-moderate impairment, exercise should be the mainstay of management, and is likely to need to be prescribed by a physical therapist or other health professional skilled in neurological rehabilitation.

Muscles with severe impairment are likely to be more limited in their ability to exercise, and may require help to do this. They may require additional interventions, to manage the greater neurological impairment and also greater secondary complications. These interventions may include serial casting, flexibility exercise such as sustained positioning programs, and medical interventions.

Research has clearly shown that exercise is beneficial for impaired muscles, even though it was previously believed that strength exercise would "increase" muscle tone and impair muscle performance further. Also, in previous decades there has been a strong focus on other interventions for impaired muscles, particularly stretching and splinting, but the evidence does not support these as effective. One of the challenges for health professionals working with UMNS movement disorders is that the degree of muscle weakness makes developing an exercise programme difficult. For muscles that lack any volitional control, such as after complete spinal cord injury, exercise may be assisted, and may require equipment, such as using a standing frame to sustain a standing position. Often, muscles require specific stimulation to achieve small amounts of activity, which is most often achieved by weight-bearing (e.g. positioning and supporting a limb such that it supports body weight) or by stimulation to the muscle belly (such as electrical stimulation or vibration).

Medical interventions may include such medications as baclofen, diazepam, dantrolene, or clonazepam. Phenol injections or botulinum toxin injections into the muscle belly can be used to attempt to dampen the signals between nerve and muscle. The effectiveness of medications varies between individuals, and varies based on location of the upper motor neuron lesion (in the brain or the spinal cord). Medications are commonly used for movement disorders, but research has not shown functional benefit for some drugs. Some studies have shown that medications have been effective in decreasing spasticity, but that this has not been accompanied by functional benefits.

In some cases, spastic cerebral palsy is caused by genetic factors.

The genetic factors for spastic cerebral palsy include:

Although it has its origins in a brain injury, spastic CP can largely be thought of as a collection of orthopaedic and neuromuscular issues because of how it manifests symptomatically over the course of the person's lifespan. It is therefore not the same as "brain damage" and it need not be thought of as such. Spastic quadriplegia in particular, especially if it is combined with verbal speech challenges and strabismus, may be misinterpreted by the general population as alluding to cognitive dimensions to the disability atop the physical ones, but this is false; the intelligence of a person with any type of spastic CP is unaffected by the condition "of the spasticity itself".

In spastic cerebral palsy in children with low birth weights, 25% of children had hemiplegia, 37.5% had quadriplegia, and 37.5% had diplegia.

The severity of impairment and related prognosis is dependent on the location and severity of brain lesions. Up to 50% of patients will achieve some degree of ambulation. Speech problems, such as dysarthria, are common to these patients.

Although HSP is a progressive condition, the prognosis for individuals with HSP varies greatly. It primarily affects the legs although there can be some upperbody involvement in some individuals. Some cases are seriously disabling while others are less disabling and are compatible with a productive and full life. The majority of individuals with HSP have a normal life expectancy.

Patients can often live with PLS for many years and very often outlive their neurological disease and succumb to some unrelated condition. There is currently no effective cure, and the progression of symptoms varies. Some people may retain the ability to walk without assistance, but others eventually require wheelchairs, canes, or other assistive devices.

Hypertonia is a term sometimes used synonymously with spasticity and rigidity in the literature surrounding damage to the central nervous system, namely upper motor neuron lesions. Impaired ability of damaged motor neurons to regulate descending pathways gives rise to disordered spinal reflexes, increased excitability of muscle spindles, and decreased synaptic inhibition. These consequences result in abnormally increased muscle tone of symptomatic muscles. Some authors suggest that the current definition for spasticity, the velocity-dependent over-activity of the stretch reflex, is not sufficient as it fails to take into account patients exhibiting increased muscle tone in the absence of stretch reflex over-activity. They instead suggest that "reversible hypertonia" is more appropriate and represents a treatable condition that is responsive to various therapy modalities like drug and/or physical therapy.

Symptoms associated with central nervous systems disorders are classified into positive and negative categories. Positive symptoms include those that increase muscle activity through hyper-excitability of the stretch reflex (i.e., rigidity and spasticity) where negative symptoms include those of insufficient muscle activity (i.e. weakness) and reduced motor function. Often the two classifications are thought to be separate entities of a disorder; however, some authors propose that they may be closely related.

CP in general is a non-progressive, neurological condition that results from brain injury and malformation occurring before cerebral development is complete. ADCP is associated with injury and malformations to the extrapyramidal tracts in the basal ganglia or the cerebellum. Lesions to this region principally arise via hypoxic ischemic brain injury (HIBI) or bilirubin encephalopathy.

The most common cause of hemiparesis and hemiplegia is stroke. Strokes can cause a variety of movement disorders, depending on the location and severity of the lesion. Hemiplegia is common when the stroke affects the corticospinal tract. Other causes of hemiplegia include spinal cord injury, specifically Brown-Séquard syndrome, traumatic brain injury, or disease affecting the brain. As a lesion that results in hemiplegia occurs in the brain or spinal cord, hemiplegic muscles display features of the upper motor neuron syndrome. Features other than weakness include decreased movement control, clonus (a series of involuntary rapid muscle contractions), spasticity, exaggerated deep tendon reflexes and decreased endurance.

The incidence of hemiplegia is much higher in premature babies than term babies. There is also a high incidence of hemiplegia during pregnancy and experts believe that this may be related to either a traumatic delivery, use of forceps or some event which causes brain injury.

Other causes of hemiplegia in adults include trauma, bleeding, brain infections and cancers. Individuals who have uncontrolled diabetes, hypertension or those who smoke have a higher chance of developing a stroke. Weakness on one side of the face may occur and may be due to a viral infection, stroke or a cancer.

Upper limb paralysis refers to the loss of function of the elbow and hand. When upper limb function is absent as a result of a spinal cord injury it is a major barrier to regain autonomy. People with tetraplegia should be examined and informed concerning the options for reconstructive surgery of the tetraplegic arms and hands.

Researchers do not fully understand what causes PLS, although it is thought it could be due to a combination of environmental and genetic factors. Studies are being done to evaluate the possible causes, although linking causality can be difficult due to the relatively low number of people who are diagnosed with PLS.

Juvenile PLS may be caused by the ALS2 gene, although this condition is very rare.

In the industrialized world, the incidence of overall cerebral palsy, which includes but is not limited to spastic diplegia, is about 2 per 1000 live births. Thus far, there is no known study recording the incidence of CP in the overall nonindustrialized world. Therefore, it is safe to assume that not all spastic CP individuals are known to science and medicine, especially in areas of the world where healthcare systems are less advanced. Many such individuals may simply live out their lives in their local communities without any medical or orthopedic oversight at all, or with extremely minimal such treatment, so that they are never able to be incorporated into any empirical data that orthopedic surgeons or neurosurgeons might seek to collect. It is shocking to note that—as with people with physical disability overall—some may even find themselves in situations of institutionalization, and thus barely see the outside world at all.

From what "is" known, the incidence of spastic diplegia is higher in males than in females; the Surveillance of Cerebral Palsy in Europe (SCPE), for example, reports a M:F ratio of 1.33:1. Variances in reported rates of incidence across different geographical areas in industrialized countries are thought to be caused primarily by discrepancies in the criteria used for inclusion and exclusion.

When such discrepancies are taken into account in comparing two or more registers of patients with cerebral palsy and also the extent to which children with mild cerebral palsy are included, the incidence rates still converge toward the average rate of 2:1000.

In the United States, approximately 10,000 infants and babies are born with CP each year, and 1200–1500 are diagnosed at preschool age when symptoms become more obvious. It is interesting to note that those with extremely mild spastic CP may not even be aware of their condition until much later in life: Internet chat forums have recorded men and women as old as 30 who were diagnosed only recently with their spastic CP.

Overall, advances in care of pregnant mothers and their babies has not resulted in a noticeable decrease in CP; in fact, because medical advances in areas related to the care of premature babies has resulted in a greater survival rate in recent years, it is actually "more" likely for infants with cerebral palsy to be born into the world now than it would have been in the past. Only the introduction of quality medical care to locations with less-than-adequate medical care has shown any decreases in the incidences of CP; the rest either have shown no change or have actually shown an increase. The incidence of CP increases with premature or very low-weight babies regardless of the quality of care.

Assessment of motor control may involve several health professionals depending on the affected individual's situation, and the severity of their condition. This may include physical therapists, physicians (including neurologists and psychiatrists ) and rehabilitation physicians, orthotists, occupational therapists, and speech-language pathologists. Assessment is needed of the affected individual's goals, their function, and any symptoms that may be related to the movement disorder, such as pain. A thorough assessment then uses a clinical reasoning approach to determine why difficulties are occurring. Elements of assessment will include analysis of posture, active movement, muscle strength, movement control and coordination, and endurance, as well as muscle tone and spasticity. Impaired muscles typically demonstrate a loss of selective movement, including a loss of eccentric control (decreased ability to actively lengthen); this decreased active lengthening of a muscle is a key factor that limits motor control. While multiple muscles in a limb are usually affected in the Upper Motor Neuron Syndrome, there is usually an imbalance of muscle activity (muscle tone), such that there is a stronger pull on one side of a joint, such as into elbow flexion. Decreasing the degree of this imbalance is a common focus of muscle strengthening programs. Impaired motor control also typically features a loss of stabilisation of an affected limb or the head from the trunk, so a thorough assessment requires this to be analysed as well, and exercise to improve proximal stability may be indicated.

Secondary effects are likely to impact on assessment of impaired muscles. If muscle tone is assessed with passive muscle lengthening, increased muscle stiffness may affect the feeling of resistance to passive stretch, in addition to neurological resistance to stretch. Other secondary changes such as loss of muscle fibres following acquired muscle weakness are likely to compound the weakness arising from the upper motor neuron lesion. In severely affected muscles, there may be marked secondary changes, such as muscle contracture, particularly if management has been delayed or absent.

Spastic quadriplegia is generally caused by brain damage or disruptions in normal brain development preceding birth. According to the National Institutes of Health, there are four types of brain damage that can cause spastic quadriplegia. These include, damage to the white matter (periventricular leukomalacia), abnormal brain development (cerebral dysgenesis), bleeding in the brain (intracranial hemorrhage), and brain damage due to lack of oxygen (hypoxic-ischemic encephalopathy or intrapartum asphyxia).

The white matter of the brain is especially vulnerable between the 26th and 34th weeks of maturation, and damage to the white matter can interfere with the brain’s ability to transmit signals to the rest of the body. Spastic quadriplegia can be caused by a condition known as periventricular leukomalacia which results in the formation of lesions and holes in the white matter of the brain.

Prior to the 26th week of maturation, the fetal brain is particularly susceptible to various toxins whose effects can ultimately hinder normal development. Exposure of the brain to infectious agents is especially dangerous because they can trigger immune responses that activate cytokines and lead to inflammation of the brain. Some infections that have been linked to the development of spastic quadriplegia include meningitis, herpes, rubella, and encephalitis. A difference in blood types between the mother and the fetus can also initiate a problematic immune response and cause brain damage. Severe jaundice, can also lead to brain damage and spastic quadriplegia due to a buildup of bilirubin in the blood.

Bleeding in the brain caused by fetal strokes, blood clots, weak and malformed blood vessels, or high maternal blood pressure may also lead to brain damage causing spastic quadriplegia. Maternal infection, most specifically pelvic inflammatory disease, has been shown to increase the risk of fetal stroke.

Hypoxia, lack of oxygen to the brain, can also cause damage in the cerebral motor cortex and other brain regions. This lack of oxygen can be the result of placenta malfunction, womb rupture, umbilical cord damage, low maternal blood pressure or asphyxia during labor and delivery.

Children who experienced many complications during birth, such as, prematurity, insufficient oxygen, low birthweight, aspiration, head injury, or bleeding in the brain have a greater risk of developing spastic quadriplegia. Children whose mothers were ill during the pregnancy or did not receive adequate nutrition are also more likely to develop the disease.

Pseudobulbar palsy is the result of damage of motor fibers traveling from the cerebral cortex to the lower brain stem. This damage might arise in the course of a variety of neurological conditions that involve demyelination and bilateral corticobulbar lesions. Examples include:

- Vascular causes: bilateral hemisphere infarction, CADASIL syndrome

- Progressive supranuclear palsy

- Amyotrophic lateral sclerosis

- Parkinson's disease and related multiple system atrophy

- Various motor neuron diseases, especially those involving demyelination

- Multiple sclerosis and other inflammatory disorders

- High brain stem tumors

- Metabolic causes: osmotic demyelination syndrome

- Neurological involvement in Behçet's disease

- Brain trauma

Delayed diagnosis of cervical spine injury has grave consequences for the victim. About one in 20 cervical fractures are missed and about two-thirds of these patients have further spinal-cord damage as a result. About 30% of cases of delayed diagnosis of cervical spine injury develop permanent neurological deficits. In high-level cervical injuries, total paralysis from the neck can result. High-level tetraplegics (C4 and higher) will likely need constant care and assistance in activities of daily living, such as getting dressed, eating and bowel and bladder care. Low-level tetraplegics (C5 to C7) can often live independently.

Even with "complete" injuries, in some rare cases, through intensive rehabilitation, slight movement can be regained through "rewiring" neural connections, as in the case of the late actor Christopher Reeve.

In the case of cerebral palsy, which is caused by damage to the motor cortex either before, during (10%), or after birth, some people with tetraplegia are gradually able to learn to stand or walk through physical therapy.

Quadriplegics can improve muscle strength by performing resistance training at least three times per week. Combining resistance training with proper nutrition intake can greatly reduce co-morbidities such as obesity and type 2 diabetes.

"Primary dystonia" is suspected when the dystonia is the only sign and there is no identifiable cause or structural abnormality in the central nervous system. It is suspected to be caused by a pathology of the central nervous system, likely originating in those parts of the brain concerned with motor function, such as the basal ganglia, and the GABA (gamma-aminobutyric acid) producing Purkinje neurons. The precise cause of primary dystonia is unknown. In many cases it may involve some genetic predisposition towards the disorder combined with environmental conditions.

"Secondary dystonia" refers to dystonia brought on by some identified cause, such as head injury, drug side effect (e.g. tardive dystonia), or neurological disease (e.g. Wilson's disease).

Meningitis and encephalitis caused by viral, bacterial, and fungal infections of the brain have been associated with dystonia. The main mechanism is inflammation of the blood vessels, causing restriction of blood flow to the basal ganglia. Other mechanisms include direct nerve injury by the organism or a toxin, or autoimmune mechanisms.

Environmental and task-related factors are suspected to trigger the development of focal dystonias because they appear disproportionately in individuals who perform high precision hand movements such as musicians, engineers, architects, and artists. Chlorpromazine can also cause dystonia, which can be often misjudged as a seizure.

Neuroleptic drugs often cause dystonia, including oculogyric crisis.

Misfunction of the sodium-potassium pump may be a factor in some dystonias. The - pump has been shown to control and set the intrinsic activity mode of cerebellar Purkinje neurons. This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients; but could be a computational element in the cerebellum and the brain. Indeed, an ouabain block of - pumps in the cerebellum of a live mouse results in it displaying ataxia and dystonia. Ataxia is observed for lower ouabain concentrations, dystonia is observed at higher ouabain concentrations. A mutation in the - pump (ATP1A3 gene) can cause rapid onset dystonia parkinsonism. The parkinsonism aspect of this disease is thought to be attributable to malfunctioning - pumps in the basal ganglia; the dystonia aspect is thought to be attributable to malfunctioning - pumps in the cerebellum (that act to corrupt its input to the basal ganglia) possibly in Purkinje neurons.

Cerebellum issues causing dystonia is described by Filip et al. 2013: "Although dystonia has traditionally been regarded as a basal ganglia dysfunction, recent provocative evidence has emerged of cerebellar involvement in the pathophysiology of this enigmatic disease. It has been suggested that the cerebellum plays an important role in dystonia etiology, from neuroanatomical research of complex networks showing that the cerebellum is connected to a wide range of other central nervous system structures involved in movement control to animal models indicating that signs of dystonia are due to cerebellum dysfunction and completely disappear after cerebellectomy, and finally to clinical observations in secondary dystonia patients with various types of cerebellar lesions. It is proposed that dystonia is a large-scale dysfunction, involving not only cortico-basal ganglia-thalamo-cortical pathways, but the cortico-ponto-cerebello-thalamo-cortical loop as well. Even in the absence of traditional "cerebellar signs" in most dystonia patients, there are more subtle indications of cerebellar dysfunction. It is clear that as long as the cerebellum's role in dystonia genesis remains unexamined, it will be difficult to significantly improve the current standards of dystonia treatment or to provide curative treatment."

Worldwide, the prevalence of all hereditary spastic paraplegias combined is estimated to be 2 to 6 in 100,000 people. A Norwegian study of more than 2.5 million people published in March 2009 has found an HSP prevalence rate of 7.4/100,000 of population – a higher rate, but in the same range as previous studies. No differences in rate relating to gender were found, and average age at onset was 24 years. In the United States, Hereditary Spastic Paraplegia is listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institutes of Health which means that the disorder affects less than 200,000 people in the US population.

Spastic diplegia's particular type of brain damage inhibits the proper development of upper motor neuron function, impacting the motor cortex, the basal ganglia and the corticospinal tract. Nerve receptors in the spine leading to affected muscles become unable to properly absorb gamma amino butyric acid (GABA), the amino acid that regulates muscle tone in humans. Without GABA absorption to those particular nerve rootlets (usually centred, in this case, around the sectors L1-S1 and L2-S2), affected nerves (here, the ones controlling the legs) perpetually fire the message for their corresponding muscles to permanently, rigidly contract, and the muscles become permanently hypertonic (spastic).

The abnormally high muscle tone that results creates lifelong difficulty with all voluntary and passive movement in the legs, and in general creates stress over time—depending on the severity of the condition in the individual, the constant spasticity ultimately produces pain, muscle/joint breakdown including tendinitis and arthritis, premature physical exhaustion (i.e., becoming physically exhausted even when you internally know that you have more energy than you are able to use), contractures, spasms, and progressively worse deformities/mis-alignments of bone structure around areas of the tightened musculature as the person's years progress. Severe arthritis, tendinitis, and similar breakdown can start as early as the spastic diplegic person's mid-20s (as a comparison, typical people with normal muscle tone are not at risk of arthritis, tendinitis, and similar breakdown until well into their 50s or 60s, if even then).

No type of CP is officially a progressive condition, and indeed spastic diplegia does not clinically "get worse" given the nerves, damaged permanently at birth, neither recover nor degrade. This aspect is clinically significant because other neuromuscular conditions with similar surface characteristics in their presentations, like most forms of multiple sclerosis, indeed do degrade the body over time and do involve actual progressive worsening of the condition, including the spasticity often seen in MS. However, spastic diplegia is indeed a chronic condition; the symptoms themselves cause compounded effects on the body that are typically just as stressful on the human body as a progressive condition is. Despite this reality and the fact that muscle tightness is the symptom of spastic diplegia and not the cause, symptoms rather than cause are typically seen as the primary area of focus for treatment, especially surgical treatment, except when a selective dorsal rhizotomy is brought into consideration, or when an oral baclofen regimen is attempted.

Unlike any other condition that may present with similar effects, spastic diplegia is entirely congenital in origin—that is, it is almost always acquired shortly before or during a baby's birth process. Things like exposure to toxins, traumatic brain injury, encephalitis, meningitis, drowning, or suffocation do not tend to lead to spastic diplegia in particular or even cerebral palsy generally. Overall, the most common cause of spastic diplegia is Periventricular leukomalacia, more commonly known as neonatal asphyxia or infant hypoxia—a sudden in-womb shortage of oxygen-delivery through the umbilical cord. This sudden lack of oxygen is also almost always combined with premature birth, a phenomenon that, even by itself, would inherently risk the infant developing some type of CP. On the other hand, the presence of certain maternal infections during pregnancy such as congenital rubella syndrome can also lead to spastic diplegia, since such infections can have similar end results to infant hypoxia.