Diagnosis of Harlequin syndrome is made when the individual has consistent signs and symptoms of the condition, therefore, it is made by clinical observation. In addition, a neurologist or primary care physician may require an MRI test to rule out similar disorders such as Horner's syndrome, Adie's syndrome, and Ross' syndrome. In an MRI, a radiologist may observe areas near brain or spinal cord for lesions, or any damage to the nerve endings. It is also important that the clinician rules out traumatic causes by performing autonomic function tests. Such tests includes the following: tilt table test, orthostatic blood pressure measurement, head-up test, valsalva maneuver, thermoregulatory sweat test, tendon reflex test, and electrocardiography (ECG). CT scan of the heart and lungs may also be performed to rule out a structural underlying lesion. The medical history of the individual should be carefully noted.

Evaluation of a child with torticollis begins with history taking to determine circumstances surrounding birth and any possibility of trauma or associated symptoms. Physical examination reveals decreased rotation and bending to the side opposite from the affected muscle. Some say that congenital cases more often involve the right side, but there is not complete agreement about this in published studies. Evaluation should include a thorough neurologic examination, and the possibility of associated conditions such as developmental dysplasia of the hip and clubfoot should be examined. Radiographs of the cervical spine should be obtained to rule out obvious bony abnormality, and MRI should be considered if there is concern about structural problems or other conditions.

Ultrasonography is another diagnostic tool that has high frequency sound waves used to visualize the muscle tissue. A colour histogram can also be used to determine cross sectional area and thickness of the muscle.

Evaluation by an optometrist or an ophthalmologist should be considered in children to ensure that the torticollis is not caused by vision problems (IV cranial nerve , nystagmus-associated "null position," etc.).

Differential diagnosis for torticollis involves

- Cranial nerve IV palsy

- Spasmus nutans

- Sandifer syndrome

- Myasthenia gravis

Cervical dystonia appearing in adulthood has been believed to be idiopathic in nature, as specific imaging techniques most often find no specific cause.

One possible cause of Harlequin syndrome is a lesion to the preganglionic or postganglionic cervical sympathetic fibers and parasympathetic neurons of the ciliary ganglion. It is also believed that torsion (twisting) of the thoracic spine can cause blockage of the anterior radicular artery leading to Harlequin syndrome. The sympathetic deficit on the denervated side causes the flushing of the opposite side to appear more pronounced. It is unclear whether or not the response of the undamaged side was normal or excessive, but it is believed that it could be a result of the body attempting to compensate for the damaged side and maintain homeostasis.

Since the cause and mechanism of Harlequin syndrome is still unknown, there is no way to prevent this syndrome.

Initially, the condition is treated with physical therapies, such as stretching to release tightness, strengthening exercises to improve muscular balance, and handling to stimulate symmetry. A TOT collar is sometimes applied. Early initiation of treatment is very important for full recovery and to decrease chance of relapse.

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.

X-rays of the hip may suggest and/or verify the diagnosis. X-rays usually demonstrate a flattened, and later fragmented, femoral head. A bone scan or MRI may be useful in making the diagnosis in those cases where X-rays are inconclusive. Usually, plain radiographic changes are delayed 6 weeks or more from clinical onset, so bone scintigraphy and MRI are done for early diagnosis. MRI results are more accurate, i.e. 97 to 99% against 88 to 93% in plain radiography. If MRI or bone scans are necessary, a positive diagnosis relies upon patchy areas of vascularity to the capital femoral epiphysis (the developing femoral head).

Traditional autonomic testing is used to aid in the diagnosis of AAG. These tests can include a Tilt Table Test (TTT), thermoregulatory sweat test (TST), quantitative sudomotor autonomic reflex testing (QSART) and various blood panels. Additionally, a blood test showing high levels of the antibody ganglionic nicotenic acetylcholine receptor (gAChr) occur in about 50% of patients with AAG (seropositive AAG). The seronegative patients (those without detectable gAChR levels) are theorized to have one or more different antibodies responsible for the autonomic dysfunction. However, both seropositive and seronegative patients have been seen to respond to the same treatments. A paraneoplastic panel may also be ordered to rule out paraneoplastic syndrome.

Diagnosis of MSA can be challenging because there is no test that can definitively make or confirm the diagnosis in a living patient. Clinical diagnostic criteria were defined in 1998 and updated in 2007. Certain signs and symptoms of MSA also occur with other disorders, such as Parkinson's disease, making the diagnosis more difficult.

Both MRI and CT scanning frequently show a decrease in the size of the cerebellum and pons in those with cerebellar features. The putamen is hypodense on T2-weighted MRI and may show an increased deposition of iron in Parkinsonian form. In cerebellar form, a "hot cross" sign has been emphasized; it reflects atrophy of the pontocereballar fibers that manifest in T2 signal intensity in atrophic pons.

A definitive diagnosis can only be made pathologically on finding abundant glial cytoplasmic inclusions in the central nervous system.

In some cases Meige's syndrome can be reversed when it is caused by medication. It has been theorized that it is related to cranio-mandibular orthopedic misalignment, a condition that has been shown to cause a number of other movement disorders (Parkinon's, tourettes, and torticollis). This theory is supported by the fact that the trigeminal nerve is sensory for blink reflex, and becomes hypertonic with craniomandibular dysfunction. Palliative treatments are available, such as botulinum toxin injections.

There are a number of known causes of myopathy, and it is only once these have been ruled out that a clinician will assign an idiopathic inflammatory myopathy (IIM) syndrome to a case. The usual criteria for a diagnosis of PM are weakness in muscles of the head, neck, trunk, upper arms or upper legs; raised blood serum concentrations of some muscle enzymes such as creatine kinase; unhealthy muscle changes on electromyography; and biopsy findings of (i) muscle cell degeneration and regeneration and (ii) chronic inflammatory infiltrates in muscle cells. If heliotrope (purple) rash or Gottron's papules are also present, then the diagnosis is DM. In DM, myositis may not be clinically apparent but detectable via biopsy or MRI. If the criteria for PM are met but muscle weakness also affects the hands and feet or is not accompanied by pain IBM should be suspected, and confirmed when muscle cell biopsy reveals (i) cytoplasmic vacuoles fringed by basophilic granules and (ii) inflammatory infiltrate comprising mostly CD8 T lymphocytes and macrophages; and electron microscopy reveals filamentous inclusions in both cytoplasm and nucleus.

Children younger than 6 have the best prognosis, since they have time for the dead bone to revascularize and remodel, with a good chance that the femoral head will recover and remain spherical after resolution of the disease. Children who have been diagnosed with Perthes' disease after the age of 10 are at a very high risk of developing osteoarthritis and coxa magna. When an LCP disease diagnosis occurs after age 8, a better outcome results with surgery rather than nonoperative treatments. Shape of femoral head at the time when Legg-Calve Perthes disease heals is the most important determinant of risk for degenerative arthritis; hence, the shape of femoral head and congruence of hip are most useful outcome measures.

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

There have been few randomized treatment trials, due to the relative rarity of inflammatory myopathies. The goal of treatment is improvement in activities of daily living and muscle strength. Suppression of immune system activity (immunosuppression) is the treatment strategy. Patients with PM or DM almost always improve to some degree in response to treatment, at least initially, and many recover fully with maintenance therapy. (If there is no initial improvement from treatment of PM or DM, the diagnosis should be carefully re-examined.) There is no proven effective therapy for IBM, and most IBM patients will need assistive devices such as a cane, a walking frame or a wheelchair. The later in life IBM arises, the more aggressive it appears to be.

Where an underlying neoplasm is the cause, treatment of this condition is indicated in order to reduce progression of symptoms. For cases without a known cause, treatment involves suppression of the immune system with corticosteroid treatment, intravenous immunoglobulin, immunosuppressive agents like Rituximab, Cellcept, or Imuran or plasmapheresis.

MSA usually progresses more quickly than Parkinson's disease. There is no remission from the disease. The average remaining lifespan after the onset of symptoms in patients with MSA is 7.9 years. Almost 80% of patients are disabled within five years of onset of the motor symptoms, and only 20% survive past 12 years. Rate of progression differs in every case and speed of decline may vary widely in individual patients.

O’Sullivan and colleagues (2008) identified early autonomic dysfunction to be the most important early clinical prognostic feature regarding survival in MSA. Patients with concomitant motor and autonomic dysfunction within three years of symptom onset had a shorter survival duration, in addition to becoming wheelchair dependent and bed-ridden at an earlier stage than those who developed these symptoms after three years from symptom onset. Their study also showed that when patients with early autonomic dysfunction develop frequent falling, or wheelchair dependence, or severe dysphagia, or require residential care, there is a shorter interval from this point to death.

Diagnosis can be difficult as symptoms may be nonspecific. A CT scan of the head is typically recommended if a concern is present. While retinal bleeding is common, it can also occur in other conditions.

Scoliosis is defined as a three-dimensional deviation in the axis of a person's spine In the diagnostic sense, it is defined as a spinal curvature of more than 10 degrees to the right or left as the examiner faces the person, i.e. in the coronal plane. Deformity may also exist to the front or back as the examiner looks at the person from the side, i.e. in the sagittal plane.

Scoliosis has been described as a biomechanical deformity, the progression of which depends on asymmetric forces otherwise known as the Heuter-Volkmann law.

People who initially present with scoliosis are examined to determine whether the deformity has an underlying cause. During a physical examination, the following are assessed to exclude the possibility of underlying condition more serious than simple scoliosis.

The person's gait is assessed, and there is an exam for signs of other abnormalities (e.g., spina bifida as evidenced by a dimple, hairy patch, lipoma, or hemangioma). A thorough neurological examination is also performed, the skin for "café au lait" spots, indicative of neurofibromatosis, the feet for cavovarus deformity, abdominal reflexes and muscle tone for spasticity.

When a person can cooperate, he or she is asked to bend forward as far as possible. This is known as the Adams Forward Bend Test and is often performed on school students. If a prominence is noted, then scoliosis is a possibility and an X-ray may be done to confirm the diagnosis.

As an alternative, a scoliometer may be used to diagnose the condition.

When scoliosis is suspected, weight-bearing full-spine AP/coronal (front-back view) and lateral/sagittal (side view) X-rays are usually taken to assess the scoliosis curves and the kyphosis and lordosis, as these can also be affected in individuals with scoliosis. Full-length standing spine X-rays are the standard method for evaluating the severity and progression of the scoliosis, and whether it is congenital or idiopathic in nature. In growing individuals, serial radiographs are obtained at three- to 12-month intervals to follow curve progression, and, in some instances, MRI investigation is warranted to look at the spinal cord.

The standard method for assessing the curvature quantitatively is measuring the Cobb angle, which is the angle between two lines, drawn perpendicular to the upper endplate of the uppermost vertebra involved and the lower endplate of the lowest vertebra involved. For people with two curves, Cobb angles are followed for both curves. In some people, lateral-bending X-rays are obtained to assess the flexibility of the curves or the primary and compensatory curves.

Congenital and idiopathic scoliosis that develops before the age of 10 is referred to as early onset scoliosis (EOS). Scoliosis that develops after 10 is referred to as adolescent idiopathic scoliosis.

Genetic testing for AIS, which became available in 2009 and is still under investigation, attempts to gauge the likelihood of curve progression.

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.

The best imaging modality for idiopathic orbital inflammatory disease is contrast-enhanced thin section magnetic resonance with fat suppression. The best diagnostic clue is a poorly marginated, mass-like enhancing soft tissue involving any area of the orbit.

Overall, radiographic features for idiopathic orbital inflammatory syndrome vary widely. They include inflammation of the extraocular muscles (myositis) with tendinous involvement, orbital fat stranding, lacrimal gland inflammation and enlargement (dacryoadenitis), involvement of the optic sheath complex, uvea, and sclera, a focal intraorbital mass or even diffuse orbital involvement. Bone destruction and intracranial extension is rare, but has been reported. Depending on the area of involvement, IOI may be categorized as:

- Myositic

- Lacrimal

- Anterior – Involvement of the globe, retrobulbar orbit

- Diffuse – Multifocal intraconal involvement with or without an extraconal component

- Apical – Involving the orbital apex and with intracranial involvement

Tolosa–Hunt syndrome is a variant of orbital pseudotumor in which there is extension into the cavernous sinus through the superior orbital fissure. Another disease variant is Sclerosing pseudotumor, which more often presents bilaterally and may extend into the sinuses.

CT findings

In non-enhanced CT one may observe a lacrimal, extra-ocular muscle, or other orbital mass. It may be focal or infiltrative and will have poorly circumscribed soft tissue. In contrast-enhanced CT there is moderate diffuse irregularity and enhancement of the involved structures. A dynamic CT will show an attenuation increase in the late phase, contrary to lymphoma where there is an attenuation decrease. Bone CT will rarely show bone remodeling or erosion, as mentioned above.

MR findings

On MR examination there is hypointensity in T1 weighted imaging (WI), particularly in sclerosing disease. T1WI with contrast will show moderate to marked diffuse irregularity and enhancement of involved structures. T2 weighted imaging with fat suppression will show iso- or slight hyperintensity compared to muscle. There is also decreased signal intensity compared to most orbital lesions due to cellular infiltrate and fibrosis. In chronic disease or sclerosing variant, T2WI with FS will show hypointensity (due to fibrosis). Findings on STIR (Short T1 Inversion Recovery) are similar to those on T2WI FS. In Tolosa–Hunt syndrome, findings include enhancement and fullness of the anterior cavernous sinus and superior orbital fissure in T1WI with contrast, while MRA may show narrowing of cavernous sinus internal carotid artery (ICA).

Ultrasonographic findings

On grayscale ultrasound there is reduced reflectivity, regular internal echoes, and weak attenuation, in a way, similar to lymphoproliferative lesions.

While the findings of AHT are complex and many, they are often referred to as a "triad". The process of inferring violent or abusive shaking from the findings in the SBS diagnosis has also been referred to as a hypothesis.

In 2000, Rob Parish, Deputy Director of the National Center on Shaken Baby Syndrome, summarized the "triad" as follows: "Often referred to as the “triad”, the consensus continues to be that a collection of (1)damage to the brain, evidenced by severe brain swelling and/or diffuse traumatic axonal injury; (2) bleeding under the membranes which cover the brain, usually subdural and/or subarachnoid bleeding; and, (3) bleeding in the layers of the retina, often accompanied by other ocular damage, when seen in young children or infants, is virtually diagnostic of severe, whiplash shaking of the head."

SBS may be misdiagnosed, underdiagnosed, and overdiagnosed, and caregivers may lie or be unaware of the mechanism of injury. Commonly, there are no externally visible signs of the condition. Examination by an experienced ophthalmologist is often critical in diagnosing shaken baby syndrome, as particular forms of ocular bleeding are quite characteristic. Magnetic resonance imaging may also depict retinal bleeds; this may occasionally be useful if an ophthalmologist examination is delayed or unavailable. Conditions that must be ruled out include hydrocephalus, sudden infant death syndrome (SIDS), seizure disorders, and infectious or congenital diseases like meningitis and metabolic disorders. CT scanning and magnetic resonance imaging are used to diagnose the condition. Conditions that may accompany SBS include bone fractures, injury to the cervical spine (in the neck), retinal bleeding, cerebral bleed or atrophy, hydrocephalus, and papilledema (swelling of the optic disc).

The terms "non-accidental head injury" or "inflicted traumatic brain injury" have been suggested instead of "SBS".

The connection of the triad to episodes of traumatic shaking is controversial with a 2016 systematic review finding limited scientific evidence associating the triad to episodes of traumatic shaking, and insufficient evidence for using the triad to identify such episodes. The connection is controversial in part following cases where parents of children exhibiting the triad have, in addition to losing custody, been jailed or sentenced to death.

Usually the diagnosis is established on clinical grounds. Tremors can start at any age, from birth through advanced ages (senile tremor). Any voluntary muscle in the body may be affected, although the tremor is most commonly seen in the hands and arms and slightly less commonly in the neck (causing the person's head to shake), tongue, and legs. A resting tremor of the hands is sometimes present. Tremor occurring in the legs might be diagnosable as orthostatic tremor.

ET occurs within multiple neurological disorders besides Parkinson's Disease. This includes migraine disorders, where co-occurrences between ET and migraines have been examined.

Although dystonias may be induced by chemical exposure/ingestion, brain injury, or hereditary/genetic predisposition, the task-specific focal dystonias such as writer's cramp are a unique challenge to diagnose and treat. Some cases may respond to chemical injections - botulinum toxin (botox) is often cited, though it is not helpful in all cases. Behavioral retraining attempts may include writing devices, switching hands, physical therapy, biofeedback, constraint-induced motion therapy, and others. Some writing instruments allow variations of pressure application for use. None of these are effective in all cases, however. The work of Dr. Joaquin Farias has shown that proprioceptive stimulation can induce neuroplasticity, making it possible for patients to recover substantial function that was lost from focal dystonia.

Anticholinergics such as Artane can be prescribed for off-label use, as some sufferers have had success.

White dog shaker syndrome (also known as idiopathic steroid responsive shaker syndrome, shaker dog syndrome and "little white shakers" syndrome; Latin name Idiopathic Cerebellitis) causes full body tremors in small dog breeds. It is most common in West Highland White Terriers, Maltese, Bichons, and Poodles, and other small dogs. There is a sudden onset of the disease at one to two years of age. It is more likely to occur, and the symptom is worse during times of stress. Nystagmus, difficulty walking, and seizures may occur in some dogs.

The cause is unknown, but it may be mediated by the immune system. One theory is that there is an autoimmune-induced generalized deficiency of neurotransmitters. Cerebrospinal fluid analysis may reveal an increased number of lymphocytes. Treatment with corticosteroids may put the dog into remission, or diazepam may control the symptoms. Typically the two drugs are used together. There is a good prognosis, and symptoms usually resolve with treatment within a week, although lifelong treatment may be necessary.

Corticosteroids remain the main treatment modality for IOI. There is usually a dramatic response to this treatment and is often viewed as pathognomonic for this disease. Although response is usually quick, many agree that corticosteroids should be continued on a tapering basis to avoid breakthrough inflammation.

Although many respond to corticosteroid treatment alone, there are several cases in which adjuvant therapy is needed. While many alternatives are available, there is no particular well-established protocol to guide adjuvant therapy. Among the available options there is: surgery, alternative corticosteroid delivery, radiation therapy, non-steroidal anti-inflammatory drugs, cytotoxic agents (chlorambucil, cyclophosphamide), corticosteroid sparing immunosuppressants (methotrexate, cyclosporine, azathioprine), IV immune-globin, plasmapheresis, and biologic treatments (such as TNF-α inhibitors).