Benign fasciculation syndrome is a diagnosis of exclusion; that is, other potential causes for the twitching (mostly forms of neuropathy or motor neuron diseases such as ALS) must be ruled out before BFS can be assumed. An important diagnostic tool here is electromyography (EMG). Since BFS appears to cause no actual nerve damage (at least as seen on the EMG), patients will likely exhibit a completely normal EMG (or one where the only abnormality seen is fasciculations).

Another important step in diagnosing BFS is checking the patient for clinical weakness. Clinical weakness is often determined through a series of strength tests, such as observing the patient's ability to walk on his or her heels and toes. Resistance strength tests may include raising each leg, pushing forward and backward with the foot and/or toes, squeezing with fingers, spreading fingers apart, and pushing with or extending arms and/or hands. In each such test the test provider will apply resisting force and monitor for significant differences in strength abilities of opposing limbs or digits. If such differences are noted or the patient is unable to apply any resisting force, clinical weakness may be noted.

Lack of clinical weakness along with normal EMG results (or those with only fasciculations) largely eliminates more serious disorders from potential diagnosis.

Especially for younger persons who have only LMN sign fasciculations, "In the absence of weakness or abnormalities of thyroid function or electrolytes, individuals under 40 years can be reassured without resorting to electromyography (EMG) to avoid the small but highly damaging possibility of false-positives". "Equally, however, most subspecialists will recall a small number of cases, typically men in their 50s or 60s, in whom the latency from presentation with apparently benign fasciculations to weakness (and then clear MND) was several years. Our impression is that a clue may be that the fasciculations of MND are often abrupt and widespread at onset in an individual previously unaffected by fasciculations in youth. The site of the fasciculations, for example, those in the calves versus abdomen, has not been shown to be discriminatory for a benign disorder. There is conflicting evidence as to whether the character of fasciculations differs neurophysiologically in MND".

Another abnormality commonly found upon clinical examination is a brisk reflex action known as "hyperreflexia". Standard laboratory tests are unremarkable. According to neurologist John C. Kincaid:

Treatment of ALS2-related disorders includes physical therapy and occupational therapy to promote mobility and independence and use of computer technologies and devices to facilitate writing and voice communication.

The prognosis for those suffering from diagnosed benign fasciculation syndrome is generally regarded as being good to excellent. The syndrome causes no known long-term physical damage. Patients may suffer elevated anxiety even after being diagnosed with the benign condition. Such patients are often directed towards professionals who can assist with reductions and understanding of stress/anxiety, or those who can prescribe medication to help keep anxiety under control.

Spontaneous remission has been known to occur, and in cases where anxiety is thought to be a major contributor, symptoms are typically lessened after the underlying anxiety is treated. In a 1993 study by Mayo Clinic, 121 individuals diagnosed with benign fasciculation syndrome were assessed 2–32 years (~7 years average) after diagnosis. Of those patients there were no cases of BFS progressing to a more serious illness, and 50% of the patients reported significant improvement in their symptoms at the time of the follow-up. Only 4% of the patients reported symptoms being worse than those present at the time of their diagnosis.

Hereditary spastic paraplegias can be classified based on the symptoms; mode of inheritance; the patient’s age at onset; the affected genes; and biochemical pathways involved.

Diagnosis can be made by EEG. In case of epileptic spasms, EEG shows typical patterns.

SPS is diagnosed by evaluating clinical findings and excluding other conditions. There is no specific laboratory test that confirms its presence. Underdiagnosis and misdiagnosis are common.

The presence of antibodies against GAD is the best indication of the condition that can be detected by blood and cerebrospinal fluid (CSF) testing. Anti-GAD65 is found in about 80 percent of SPS patients. Anti-thyroid, anti-intrinsic factor, anti-nuclear, anti-RNP, and anti-gliadin are also often present in blood tests. Electromyography (EMG) demonstrates involuntary motor unit firing in SPS patients. EMG can confirm the diagnosis by noting spasms in distant muscles as a result of subnoxious stimulation of cutaneous or mixed nerves. Responsiveness to diazepam helps confirm that the patient is suffering from SPS, as this decreases stiffness and motor unit potential firing.

The same general criteria are used to diagnose paraneoplastic SPS as the normal form of the condition. Once SPS is diagnosed, poor response to conventional therapies and the presence of cancer indicate that it may be paraneoplastic. CT scans are indicated for SPS patients who respond poorly to therapy to determine if this is the case.

A variety of conditions have similar symptoms to SPS, including myelopathies, dystonias, spinocerebellar degenerations, primary lateral sclerosis, neuromyotonia, and some psychogenic disorders. Tetanus, neuroleptic malignant syndrome, malignant hyperpyrexia, chronic spinal interneuronitis, serotonin syndrome, Multiple sclerosis, Parkinson's disease, and Isaacs syndrome should also be excluded.

Patients' fears and phobias often incorrectly lead doctors to think their symptoms are psychogenic, and they are sometimes suspected of malingering. It takes an average of six years after the onset of symptoms before the disease is diagnosed.

Many features of gerodermia osteodysplastica (GO) and another autosomal recessive form of cutis laxa, wrinkly skin syndrome (WSS, ""), are similar to such an extent that both disorders were believed to be variable phenotypes of a single disorder.

Several delineating factors, however, suggest that gerodermia osteodysplastica and wrinkly skin syndrome are distinct entities, but share the same clinic spectrum.

While the prevailing feature of wrinkly, loose skin is more localized with GO, it is usually systemic, yet eases in severity with age during the course of WSS. Also, as the fontanelles ("soft spots") are usually normal on the heads of infants with GO, they are often enlarged in WSS infants.

While WSS is associated with mutations of genes on chromosomes 2, 5, 7, 11 and 14; GO has been linked to mutations in the protein GORAB. A serum sialotransferrin type 2 pattern, also observed with WSS, is not present in GO patients.

But perhaps the most notable feature, differentiating GO from WSS and similar cutis laxa disorders, is the age-specific metaphyseal peg sometimes found in GO-affected long bone, near the knee. Not appearing until around age 4–5, then disappearing by physeal closure, this oddity of bone is thought to represent a specific genetic marker unique to GO and its effects on bone development.

Initial diagnosis of HSPs relies upon family history, the presence or absence of additional signs and the exclusion of other nongenetic causes of spasticity, the latter being particular important in sporadic cases.

Cerebral and spinal MRI is an important procedure performed in order to rule out other frequent neurological conditions, such as multiple sclerosis, but also to detect associated abnormalities such as cerebellar or corpus callosum atrophy as well as white matter abnormalities. Differential diagnosis of HSP should also exclude spastic diplegia which presents with nearly identical day-to-day effects and even is treatable with similar medicines such as baclofen and orthopedic surgery; at times, these two conditions may look and feel so similar that the only "perceived" difference may be HSP's hereditary nature versus the explicitly non-hereditary nature of spastic diplegia (however, unlike spastic diplegia and other forms of spastic cerebral palsy, HSP cannot be reliably treated with selective dorsal rhizotomy).

Ultimate confirmation of HSP diagnosis can only be provided by carrying out genetic tests targeted towards known genetic mutations.

Several disorders may appear similar to CBPS and need to be distinguished in the process of diagnosing CBPS. These include pachygyria, double cortex syndrome, and lissencephaly, all of which are classified along with CBPS as neuronal migration disorders. Diagnostic tests for CBPS include electroencephalograms, CT scanning, and magnetic resonance imaging.

Satoyoshi syndrome, also known as Komura-Guerri syndrome, is a rare progressive disorder of presumed autoimmune cause, characterized by painful muscle spasms, alopecia, diarrhea, endocrinopathy with amenorrhoea and secondary skeletal abnormalities. The syndrome was first reported in 1967 by Eijiro Satoyoshi and Kaneo Yamada in Tokyo, Japan. To this date, fewer than 50 cases worldwide have been reported for the Satoyoshi syndrome.

People with the syndrome typically develop symptoms of the illness at a young age, usually between the age of six and fifteen years old. The initial symptoms are muscle spasms in the legs and alopecia, also known as baldness. The spasms are painful and progressive and their frequency varies from 1 or 2 to 100 per day, each lasting a few minutes. It can be sufficiently severe to produce abnormal posturing of the affected limbs, particularly the thumbs. With progression the illness involves the pectoral girdle and trunk muscles and finally the masseters and temporal muscles. The spasms usually spare the facial muscles. Severe spasms can interfere with respiration and speech. During an attack-free period, non-stimulus-sensitive myoclonus can occur in the arms, legs and neck. Diarrhea occurs in the first 2–3 years with intolerance to carbohydrate and high glucose diets. Endocrinopathy manifests as amenorrhea and hypoplasia of the uterus. Affected children fail to attain height after 10–12 years of age.

The syndrome is not known to be a primary cause of mortality, but some patients have died as a result of secondary complications, such as respiratory failure and malnourishment.

In one 6-year-old patient antibodies to GABA-producing enzyme glutamate decarboxylase were detected.

CBPS is commonly treated with anticonvulsant therapy to reduce seizures. Therapies include anticonvulsant drugs, adrenocorticotropic hormone therapy, and surgical therapy, including focal corticectomy and callosotomy. Special education, speech therapy, and physical therapy are also used to help children with intellectual disability due to CBPS.

Occasionally the syndrome is referred to as "idiopathic" West syndrome, when a cause cannot be determined. Important diagnostic criteria are:

- Regular development until the onset of the attacks or before the beginning of the therapy

- no pathological findings in neurological or neuroradiological studies

- no evidence of a trigger for the spasms

Those are becoming rare due to modern medicine.

Meige's is commonly misdiagnosed and most doctors will have not seen this condition before. Usually a neurologist who specializes in movement disorders can detect Meige's. There is no way to detect Meige's by blood test or MRI or CT scans. OMD by itself may be misdiagnosed as TMJ.

The lack of prompt response to anticholinergic drugs in cases of idiopathic Meige's syndrome is important in differentiating it from acute dystonia, which does respond to anticholinergics.

The progression of SPS depends on whether it is a typical or abnormal form of the condition and the presence of comorbidities. Early recognition and neurological treatment can limit its progression. SPS is generally responsive to treatment, but the condition usually progresses and stabilizes periodically. Even with treatment, quality of life generally declines as stiffness precludes many activities. Some patients require mobility aids due to the risk of falls. About 65 percent of SPS patients are unable to function independently. About ten percent of SPS patients require intensive care at some point; sudden death occurs in about the same number of patients. These deaths are usually caused by metabolic acidosis or an autonomic crisis.

Patients with CHH usually suffer from cellular immunodeficiency. In the study of 108 Finnish patients with CHH there was detected mild to moderate form of lymphopenia, decreased delayed type of hypersensitivity and impaired responses to phytohaemagglutinin. This leads to susceptibility to and, in some more severe cases, mortality from infections early in childhood. There has also been detected combined immunodeficiency in some patients

Patients with CHH often have increased predispositions to malignancies.

Léri–Weill dyschondrosteosis or LWD is a rare pseudoautosomal dominant genetic disorder which results in dwarfism with short forearms and legs (mesomelic dwarfism) and a bayonet-like deformity of the forearms (Madelung's deformity).

Early journal reports of boomerang dysplasia suggested X-linked recessive inheritance, based on observation and family history. It was later discovered, however, that the disorder is actually caused by a genetic mutation fitting an autosomal dominant genetic profile.

Autosomal dominant inheritance indicates that the defective gene responsible for a disorder is located on an autosome, and only one copy of the gene is sufficient to cause the disorder, when inherited from a parent who has the disorder.

Boomerang dysplasia, although an autosomal dominant disorder, is "not" inherited because those afflicted do not live beyond infancy. They cannot pass the gene to the next generation.

Acromicric dysplasia is an extremely rare inherited disorder characterized by abnormally short hands and feet, growth retardation and delayed bone maturation leading to short stature. Most cases have occurred randomly for no apparent reason (sporadically). However, autosomal dominant inheritance has not been ruled out.

According to the disease database, Acromicric dysplasia is synonymous with Geleophysic dysplasia

(or Geleophysic Dwarfism) and Focal mucopolysaccharidosis.

There is no causative / curative therapy. Symptomatic medical treatments are focussing on symptoms caused by orthopaedic, dental or cardiac problems. Regarding perioperative / anesthesiological management, recommendations for medical professionals are published at OrphanAnesthesia.

It is caused by mutations in the SHOX gene found in the pseudoautosomal region PAR1 of the X and Y chromosomes, at band Xp22.33 or Yp11.32.

SHOX gene deletions have been identified as the major cause of Leri–Weill syndrome.

Leri–Weill dyschondrosteosis is characterized by mesomelic short stature, with bowing of the radius more so than the ulna in the forearms and bowing of the tibia while sparing the fibula.

The caloric intake of children with SRS must be carefully controlled in order to provide the best opportunity for growth. If the child is unable to tolerate oral feeding, then enteral feeding may be used, such as the percutaneous endoscopic gastrostomy.

In children with limb-length differences or scoliosis, physiotherapy can alleviate the problems caused by these symptoms. In more severe cases, surgery to lengthen limbs may be required. To prevent aggravating posture difficulties children with leg length differences may require a raise in their shoe.

Growth hormone therapy is often prescribed as part of the treatment of SRS. The hormones are given by injection typically daily from the age of 2 years old through teenage years. It may be effective even when the patient does not have a growth hormone deficiency. Growth hormone therapy has been shown to increase the rate of growth in patients and consequently prompts 'catch up' growth. This may enable the child to begin their education at a normal height, improving their self-esteem and interaction with other children. The effect of growth hormone therapy on mature and final height is as yet uncertain. There are some theories suggesting that the therapy also assists with muscular development and managing hypoglycemia.

Parastremmatic dwarfism is apparent at birth, with affected infants usually being described as "stiff", or as "twisted dwarfs" when the skeletal deformities and appearance of dwarfism further present themselves. Skeletal deformities usually develop in the sixth to twelfth month of an infant's life. The deformities may be attributed to osteomalacia, a lack of bone mineralization.

Achondroplasia can be detected before birth by prenatal ultrasound. A DNA test can be performed before birth to detect homozygosity, wherein two copies of the mutant gene are inherited, a lethal condition leading to stillbirths. Clinical features include megalocephaly, short limbs, prominent forehead, thoracolumbar kyphosis and mid-face hypoplasia. Complications like dental malocclusion, hydrocephalus and repeated otitis media can be observed. The risk of death in infancy is increased due to the likelihood of compression of the spinal cord with or without upper airway obstruction.

The Kocher–Debré–Semelaigne syndrome is hypothyroidism in infancy or childhood characterised by lower extremity or generalized muscular hypertrophy, myxoedema, short stature and cretinism. The absence of painful spasms and pseudomyotonia differentiates this syndrome from its adult form, which is Hoffmann syndrome.

The syndrome is named after Emil Theodor Kocher, Robert Debré and Georges Semelaigne.

Also known as Debre–Semelaigne syndrome or cretinism-muscular hypertrophy, hypothyroid myopathy, hypothyroidism-large muscle syndrome, hypothyreotic muscular hypertrophy in children, infantile myxoedema-muscular hypertrophy, myopathy-myxoedema syndrome, myxoedema-muscular hypertrophy syndrome, myxoedema-myotonic dystrophy syndrome.

Kocher-Debre-Semelaigne syndrome gives infant a Hercules appearance.

A skeletal survey is useful to confirm the diagnosis of achondroplasia. The skull is large, with a narrow foramen magnum, and relatively small skull base. The vertebral bodies are short and flattened with relatively large intervertebral disk height, and there is congenitally narrowed spinal canal. The iliac wings are small and squared, with a narrow sciatic notch and horizontal acetabular roof. The tubular bones are short and thick with metaphyseal cupping and flaring and irregular growth plates. Fibular overgrowth is present. The hand is broad with short metacarpals and phalanges, and a trident configuration. The ribs are short with cupped anterior ends. If the radiographic features are not classic, a search for a different diagnosis should be entertained. Because of the extremely deformed bone structure, people with achondroplasia are often "double jointed".

The diagnosis can be made by fetal ultrasound by progressive discordance between the femur length and biparietal diameter by age. The trident hand configuration can be seen if the fingers are fully extended."

Another distinct characteristic of the syndrome is thoracolumbar gibbus in infancy.