MRI is the most sensitive imaging technique that can be used for diagnosing NBD. As for the parenchymal NBD, medical doctors mainly monitor the upper brainstem lesion. In fact, it is possible that lesions extends to thalamus and basal ganglia. Another advantage of using MRI is the ability to perform Diffusion-weighted imaging, or diffusion MRI. This technique is the most sensitive tool to image an acute infarct. In the case of NBD, Diffusion MRI can determine whether the lesion were due to cerebral infarction. In other words, it can distinguish NBD from non-NBD neural disease. When only spinal cord is affected by NBD, brain looks perfectly normal when scanned by MRI. Therefore, it is necessary to scan the spinal cord as well when diagnosing possible NBD involvement. As for the non-parenchymal NBD, venous sinus thrombosis can be detected.

"...Despite its rarity, the patient's ethnic background and the typical radiographic findings should prompt the clinicians to include NBD in the differential diagnosis of optic neuritis and demyelinating disease in the young..."[5]. This quote indicates that even common symptoms such as headache should be recognized as the sign for possible NBD considering the patient's ethnic background.

There is no specific pathological testing or technique available for the diagnosis of the disease, although the International Study Group criteria for the disease are highly sensitive and specific, involving clinical criteria and a pathergy test. Behçet's disease has a high degree of resemblance to diseases that cause mucocutaneous lesions such as "Herpes simplex" labialis, and therefore clinical suspicion should be maintained until all the common causes of oral lesions are ruled out from the differential diagnosis.

Visual acuity, or color vision loss with concurrent mucocutaneous lesions or systemic Behçet's disease symptoms should raise suspicion of optic nerve involvement in Behçet's disease and prompt a work-up for Behçet's disease if not previously diagnosed in addition to an ocular work-up. Diagnosis of Behçet's disease is based on clinical findings including oral and genital ulcers, skin lesions such as erythema nodosum, acne, or folliculitis, ocular inflammatory findings and a pathergy reaction. Inflammatory markers such ESR, and CRP may be elevated. A complete ophthalmic examination may include a slit lamp examination, optical coherence tomography to detect nerve loss, visual field examinations, fundoscopic examination to assess optic disc atrophy and retinal disease, fundoscopic angiography, and visual evoked potentials, which may demonstrate increased latency. Optic nerve enhancement may be identified on Magnetic Resonance Imaging (MRI) in some patients with acute optic neuropathy. However, a normal study does not rule out optic neuropathy. Cerebrospinal fluid (CSF) analysis may demonstrate elevated protein level with or without pleocytosis. Imaging including angiography may be indicated to identify dural venous sinus thrombosis as a cause of intracranial hypertension and optic atrophy.

Surgical treatment of arterial manifestations of BD bears many pitfalls, since the obliterative endarteritis of vasa vasorum causes thickening of the medial layer and splitting of elastin fibers. Therefore, anastomotic pseudoaneurysms are likely to form, as well as pseudoaneurysms at the site of puncture in case of angiography or endovascular treatment; furthermore, early graft occlusion may occur.

For these reasons, invasive treatment should not be performed in the acute and active phases of the disease when inflammation is at its peak. The evaluation of disease’s activity is usually based on relapsing symptoms, ESR (erythrocyte sedimentation rate), and serum levels of CRP (C‐reactive protein).

Endovascular treatment can be an effective and safe alternative to open surgery, with less postoperative complications, faster recovery time, and reduced need for intensive care, while offering patency rates and procedural success rates comparable with those of surgery. This notwithstanding, long‐term results of endovascular treatment in BD are still to be determined.

The administration of immunotherapy, in association with chemotherapy or tumor removal, .

A complete recovery following immunotherapy and tumor removal. Untreated cases died within few months of onset. Some patients have a poor outcome despite sustained immunosuppression, but that is often related to tumor progression or associated with the presence of Abs directed against intracellular Ags such as GAD Abs or amphyphysin Abs, which can reflect the involvement of an additional cytotoxic T-cell mechanism in the progression of the disease.

Individuals with a history of high blood pressure, diabetes, and smoking are most susceptible to PION as they have a compromised system of blood vessel autoregulation. Hence, extra efforts may need to be taken for them in the form of careful or staged surgery or the controlling the anemia from blood loss (by administration of blood transfusions), and the careful maintenance of their blood pressure.

The American College of Rheumatology has defined a combination of physical symptoms and inflammatory changes to diagnose giant cell arteritis.

Diagnosis commonly occurs later in childhood and often occurs incidentally in asymptomatic patients or as a cause of visual impairment. The first symptoms are commonly found during routine vision screenings.

A number of examinations can be used to determine the extent of the syndrome and its severity. Fluorescein angiography is quite useful in diagnosing the disease, and the use of ultrasonography and optical coherence tomography (OCT) are helpful in confirming the disease. Neuro-ophthalmic examinations reveal pupillary defects (see Marcus Gunn Pupil). Funduscopic examinations, examinations of the fundus of the eye, allow detection of arteriovenous malformations. Neurological examinations can determine hemiparesis and paresthesias. Malformations in arteriovenous connections and irregular functions in the veins may be distinguished by fluorescein angiographies. Cerebral angiography examinations may expose AVMs in the cerebrum. MRIs are also used in imaging the brain and can allow visualization of the optic nerve and any possible atrophy. MRI, CT, and cerebral angiography are all useful for investigating the extent and location of any vascular lesions that are affecting the brain. This is helpful in determining the extent of the syndrome.

Several specific diagnostic criteria can be used to diagnose vascular dementia, including the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria, the International Classification of Diseases, Tenth Edition (ICD-10) criteria, the National Institute of Neurological Disorders and Stroke criteria, Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) criteria, the Alzheimer's Disease Diagnostic and Treatment Center criteria, and the Hachinski Ischemic Score (after Vladimir Hachinski).

The recommended investigations for cognitive impairment include: blood tests (for anemia, vitamin deficiency, thyrotoxicosis, infection, etc.), chest X-Ray, ECG, and neuroimaging, preferably a scan with a functional or metabolic sensitivity beyond a simple CT or MRI. When available as a diagnostic tool, single photon emission computed tomography (SPECT) and positron emission tomography (PET) neuroimaging may be used to confirm a diagnosis of multi-infarct dementia in conjunction with evaluations involving mental status examination. In a person already having dementia, SPECT appears to be superior in differentiating multi-infarct dementia from Alzheimer's disease, compared to the usual mental testing and medical history analysis. Advances have led to the proposal of new diagnostic criteria.

The screening blood tests typically include full blood count, liver function tests, thyroid function tests, lipid profile, erythrocyte sedimentation rate, C reactive protein, syphilis serology, calcium serum level, fasting glucose, urea, electrolytes, vitamin B-12, and folate. In selected patients, HIV serology and certain autoantibody testing may be done.

Mixed dementia is diagnosed when people have evidence of Alzheimer's disease and cerebrovascular disease, either clinically or based on neuro-imaging evidence of ischemic lesions.

Gross examination of the brain may reveal noticeable lesions and damage to blood vessels. Accumulation of various substances such as lipid deposits and clotted blood appear on microscopic views. The white matter is most affected, with noticeable atrophy (tissue loss), in addition to calcification of the arteries. Microinfarcts may also be present in the gray matter (cerebral cortex), sometimes in large numbers.

Although atheroma of the major cerebral arteries is typical in vascular dementia, smaller vessels and arterioles are mainly affected.

Suggested diagnostic criteria for cryoglobulinemic disease fall into the following obligatory and additional categories:

- Obligatory criteria: 1) cold sensitivity; 2) cutaneous symptoms (i.e. urticaria, purpura, Raynaud phenomenon, ulceration/necrosis/gangrene, and/or livedo reticularis); 3) arterial and/or venous thrombotic events; fever; 4) arthralgia/myalgia; 5) neuritis in >1 site; and 6) renal disorder.

- Additional criteria: 1) typical biopsy findings at site(s) of involvement and 2) angiogram evidence of occlusion in one or more small to medium sized arteries.

The diagnosis of secondary cryofibrinogenemia also requires evidence for the cited infectious, malignant, premalignant vasculitis, and autoimmune disorders while the diagnosis of primary cryofibriongenemia requires a lack of evidence for 1) the cited associated disorders, 2) other vascular occlusive diseases, and 3) cryoglobulinemia.

Erythema nodosum is diagnosed clinically. A biopsy can be taken and examined microscopically to confirm an uncertain diagnosis. Microscopic examination usually reveals a neutrophilic infiltrate surrounding capillaries that results in septal thickening, with fibrotic changes in the fat around blood vessels. A characteristic microscopic finding is radial granulomas, well-defined nodular aggregates of histiocytes surrounding a stellate cleft.

Additional evaluation should be performed to determine the underlying cause of erythema nodosum. This may include a full blood count, erythrocyte sedimentation rate (ESR), antistreptolysin-O (ASO) titer and throat culture, urinalysis, intradermal tuberculin test, and a chest x-ray. The ESR is typically high, the C-reactive protein elevated, and the blood showing an increase in white blood cells.

The ESR is initially very high, and falls as the nodules of erythema nodosum. The ASO titer is high in cases associated with a streptococcal throat infection. A chest X-ray should be performed to rule out pulmonary diseases, in particular sarcoidosis and Löfgren syndrome.

The treatment for Bonnet–Dechaume–Blanc syndrome is controversial due to a lack of consensus on the different therapeutic procedures for treating arteriovenous malformations. The first successful treatment was performed by Morgan et al. They combined intracranial resection, ligation of ophthalmic artery, and selective arterial ligature of the external carotid artery, but the patient did not have retinal vascular malformations.

If lesions are present, they are watched closely for changes in size. Prognosis is best when lesions are less than 3 cm in length. Most complications occur when the lesions are greater than 6 cm in size. Surgical intervention for intracranial lesions has been done successfully. Nonsurgical treatments include embolization, radiation therapy, and continued observation. Arterial vascular malformations may be treated with the cyberknife treatment. Possible treatment for cerebral arterial vascular malformations include stereotactic radiosurgery, endovascular embolization, and microsurgical resection.

When pursuing treatment, it is important to consider the size of the malformations, their locations, and the neurological involvement. Because it is a congenital disorder, there are not preventative steps to take aside from regular follow ups with a doctor to keep an eye on the symptoms so that future complications are avoided.

Success in treating the primary disease has been reported using blood clot lysing agents such as anabolic steroids (e.g. danazol or stanozolol which is no longer available in the USA), streptokinase, and streptodornase; anticoagulants such as heparin and warfarin, and immunosuppressive drug regimens such as a corticosteroid (e.g. prednisone) combined with either azathioprine of chlorambucil. Very moderate cases may do well by simply avoiding cold exposure. Treatment with a corticosteroid plus low-dose aspirin followed by maintenance therapy with an anabolic steroid where necessary are recommended for moderately severe cases. Very severe cases generally require an immunosuppressive drug regimen and if extreme or life threatening require resorting to plasmaphoresis or plasma exchange. Cryofiltration apheresis, a method to remove plasma agents by removing cold-induced precipitated material, may be an effective alternative to plasmaphoresis and plasma exchange but is still regarded as second-line therapy for cryofibirnogenemic disease treatment.

During the several years following its initial diagnosis, some 27-47% of primary cryofibrinoginemic diseases are complicated by the development of a B-cell or T-cell lymphoma. That is, the cryofibrinoginemic disease may appear to precede by years the malignant disorder to which it is associated. Accordingly, patients require careful follow-up not only to treat their primary cryofibrinoginemic disease but also to monitor them for movement to the diagnosis of secondary cryofibrinoginemic disease caused by the development of one of these hematological malignancies.

A thorough history is essential and should cover family history, diet; drug/toxin exposure social history, including tobacco and alcohol use; and occupational background, with details on whether similar cases exist among coworkers. Treatment of any chronic disease such as pernicious anemia should always be elucidated.

In most cases of nutritional/toxic optic neuropathy, the diagnosis may be obtained via detailed medical history and eye examination. Additionally, supplementary neurological imaging studies, such as MRI or enhanced CT, may be performed if the cause remains unclear.

When the details of the examination and history indicate a familial history of similar ocular or systemic disease, whether or not there is evidence of toxic or nutritional causes for disease, certain genetic tests may be required. Because there are several congenital causes of mitochondrial dysfunction, the patients history, examination, and radiological studies must be examined in order to determine the specific genetic tests required. For example, 90% of cases of Leber’s Hereditary Optic Neuropathy (LHON) are associated with three common mtDNA point mutations (m.3460G>A/MT-ND1, m.11778G>A/MT-ND4, m.14484T>C/MT-ND6) while a wider range of mtDNA mutations (MT-ND1, MT-ND5, MT-ND6; http://www.mitomap.org/) have been associated with overlapping phenotypes of LHON, MELAS, and Leigh syndrome.

A neurological examination would show evidence of muscle rigidity; weakness; and abnormal postures, movements, and tremors. If other family members are also affected, this may help determine the diagnosis. Genetic tests can confirm an abnormal gene causing the disease. However, this test is not yet widely available. Other movement disorders and diseases must be ruled out. Individuals exhibiting any of the above listed symptoms are often tested using MRI (Magnetic Resonance Imaging) for a number of neuro-related disorders. As PKAN is a disease prominently evident in the brain, MRIs are very useful in making a sound diagnosis. An MRI usually shows iron deposits in the basal ganglia. Development of diagnostic criteria continues in the hope of further separating PKAN from other forms of neurodegenerative diseases featuring NBIA.

Microscopic features of PKAN include:

- Iron granules

- Spheroid bodies

- Lewy bodies within neurons

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.

This inherited condition can be diagnosed with a blood test. If the total cholinesterase activity in the patient's blood is low, this may suggest an atypical form of the enzyme is present, putting the patient at risk of sensitivity to suxamethonium and related drugs. Inhibition studies may also be performed to give more information about potential risk. In some cases, genetic studies may be carried out to help identify the form of the enzyme that is present.

While the disease manifests early in life in most cases, diagnosis of the disease is often quite delayed. The symptoms that affected patients present vary, but the most common presenting symptoms are gastrointestinal issues such as nausea, vomiting, abdominal pain, and diarrhea, and neurologic or ocular symptoms such as hearing loss, weakness, and peripheral neuropathy. These gastrointestinal symptoms cause patients with MNGIE to be very thin and experience persistent weight loss and this often leads to MNGIE being misdiagnosed as an eating disorder. These symptoms without presentation of disordered eating and warped body image warrant further investigation into the possibility of MNGIE as a diagnosis. Presentation of these symptoms and lack of disordered eating are not enough for a diagnosis. Radiologic studies showing hypoperistalsis, large atonic stomach, dilated duodenum, diverticula, and white matter changes are required to confirm the diagnosis. Elevated blood and urine nucleoside levels are also indicative of MNGIE syndrome. Abnormal nerve conduction as well as analysis of mitochondria from liver, intestines, muscle, and nerve tissue can also be used to support the diagnosis.

A successful treatment for MNGIE has yet to be found, however, symptomatic relief can be achieved using pharmacotherapy and celiac plexus neurolysis. Celiac plexus neurolysis involves interrupting neural transmission from various parts of the gastrointestinal tract. By blocking neural transmission, pain is relieved and gastrointestinal motility increases. Stem cell therapies are currently being investigated as a potential cure for certain patients with the disease, however, their success depends on physicians catching the disease early before too much organ damage has occurred.

Due to the condition's rarity, it is frequently misdiagnosed, often as cerebral palsy. This results in patients often living their entire childhood with the condition untreated.

The diagnosis of SS can be made from a typical history, a trial of dopamine medications, and genetic testing. Not all patients show mutations in the GCH1 gene (GTP cyclohydrolase I), which makes genetic testing imperfect.

Sometimes a lumbar puncture is performed to measure concentrations of biopterin and neopterin, which can help determine the exact form of dopamine-responsive movement disorder: early onset parkinsonism (reduced biopterin and normal neopterin), GTP cyclohydrolase I deficiency (both decreased) and tyrosine hydroxylase deficiency (both normal).

In approximately half of cases, a phenylalanine loading test can be used to show decreased conversion from the amino acid phenylalanine to tyrosine. This process uses BH4 as a cofactor.

During a sleep study (polysomnography), decreased twitching may be noticed during REM sleep.

An MRI scan of the brain can be used to look for conditions that can mimic SS (for example, metal deposition in the basal ganglia can indicate Wilson's disease or pantothenate kinase-associated neurodegeneration). Nuclear imaging of the brain using positron emission tomography (PET scan) shows a normal radiolabelled dopamine uptake in SS, contrary to the decreased uptake in Parkinson's disease.

Other differential diagnoses include metabolic disorders (such as GM2 gangliosidosis, phenylketonuria, hypothyroidism, Leigh disease) primarily dystonic juvenile parkinsonism, autosomal recessive early onset parkinsonism with diurnal fluctuation, early onset idiopathic parkinsonism, focal dystonias, dystonia musculorum deformans and dyspeptic dystonia with hiatal hernia.

- Diagnosis - main

- typically referral by GP to specialist Neurological Hospital e.g. National Hospital in London.

- very hard to diagnose as condition is dynamic w.r.t. time-of-day AND dynamic w.r.t. age of patient.

- correct diagnosis only made by a consultant neurologist with a complete 24-hour day-cycle observation(with video/film) at a Hospital i.e. morning(day1)->noon->afternoon->evening->late-night->sleep->morning(day2).

- patient with suspected SS required to walk in around hospital in front of Neuro'-consultant at selected daytime intervals to observe worsening walking pattern coincident with increased muscle tension in limbs.

- throughout the day, reducing leg-gait, thus shoe heels catching one another.

- diurnal affect of condition: morning(fresh/energetic), lunch(stiff limbs), afternoon(very stiff limbs), evening(limbs worsening), bedtime(limbs near frozen).

- muscle tension in thighs/arms: morning(normal), lunch(abnormal), afternoon(very abnormal), evening(bad), bedtime(frozen solid).

- Diagnosis - additional

- lack of self-esteem at school/college/University -> eating disorders in youth thus weight gains.

- lack of energy during late-daytime (teens/adult) -> compensate by over-eating.

There are no laboratory tests used to diagnose RVT.

Observing the patient's symptoms, medical history and imaging remain the fundamental source for diagnosing RVT. Imaging is used to detect the presence of a blood clot. In an abnormal kidney with RVT, a blood clot is present in the renal vein. In cases where the renal vein is suddenly and/or fully blocked, the kidneys will enlarge, reaching its maximum size within a week. An ultrasound imaging can be used to observe and track the size of the kidneys in RVT patients. Ultrasound is not efficient for use in detecting blood flow in the renal veins and artery. Instead a color doppler ultrasound may be used to detect renal blood flow. It is most commonly used to detect RVT in patients who have undergone renal transplantation. CT angiography is currently the top choice in diagnosing RVT. It is non-invasive, relatively cheap and fast with high accuracy. CT scanning can be used to detect renal enlargement, renal tumors, blood flow and other renal pathologies. An alternative is magnetic resonance angiography or MRA. It is non-invasive, fast and avoids radiation (unlike a CT scan) but it is relatively expensive. MRA produces detailed images of the renal blood flow, vesicle walls, the kidneys and any surrounding tissue. An inferior venocavography with selective venography can be used to rule out the diagnoses of RVT.

The diagnostic criteria as of 2015 define definite MD and probable MD as follows:

Definite

1. Two or more spontaneous episodes of vertigo, each lasting 20 minutes to 12 hours

2. Audiometrically documented low- to medium-frequency sensorineural hearing loss in the affected ear on at least 1 occasion before, during, or after one of the episodes of vertigo

3. Fluctuating aural symptoms (hearing, tinnitus, or fullness) in the affected ear

4. Not better accounted for by another vestibular diagnosis

Probable

1. Two or more episodes of vertigo or dizziness, each lasting 20 minutes to 24 hours

2. Fluctuating aural symptoms (hearing, tinnitus, or fullness) in the reported ear

3. Not better accounted for by another vestibular diagnosis

A common and important symptom of MD is hypersensitivity to sounds. This hypersensitivity is easily diagnosed by measuring the loudness discomfort levels (LDLs).

Symptoms of MD overlap with migraine-associated vertigo (MAV) in many ways, but when hearing loss develops in MAV is usually in both ears, and this is rare in MD, and hearing loss generally does not progress in MAV as it does in MD.

People who have had a transient ischemic attack (TIA) and stroke can present with symptoms similar to MD, and in people at risk for stroke magnetic resonance imaging (MRI) should be conducted to exclude TIA or stroke, and as TIA is often a precursor to stroke, that risk should be managed.

Other vestibular conditions that should be excluded include vestibular paroxysmia, recurrent unilateral vestibulopathy, vestibular schwannoma, or a tumor of the endolymphatic sac.

Blood lactate and pyruvate levels usually are elevated as a result of increased anaerobic metabolism and a decreased ratio of ATP:ADP. CSF analysis shows an elevated protein level, usually >100 mg/dl, as well as an elevated lactate level.