FLAIR) demonstrates increased T2 signal within the posterior part of the internal capsule, consistent with the diagnosis of<unk> . No test can provide a definite diagnosis of<unk> , although the presence of upper and lower motor neuron signs in a single limb is strongly suggestive. Instead, the diagnosis of<unk>  is primarily based on the symptoms and signs the physician observes in the person and a series of tests to rule out other diseases. Physicians obtain the person's full medical history and usually conduct a neurologic examination at regular intervals to assess whether symptoms such as muscle weakness, atrophy of muscles, hyperreflexia, and spasticity are worsening. A number of biomarkers are being studied for the condition, but so far are not in general medical use. Diagnostic criteria The diagnosis of<unk>  is based on the El Escorial Revised criteria and the Awaji criteria. The original El Escorial criteria had four levels of diagnostic certainty, based on how many of the four spinal cord regions were involved: bulbar, cervical, thoracic, and lumbar. Definite<unk>  was defined as upper motor neuron (UMN) and lower motor neuron (LMN) signs in three spinal cord regions, probable<unk>  as UMN and LMN signs in two regions, possible<unk>  as UMN and LMN signs in only one region, and suspected<unk>  as LMN signs only. The El Escorial Revised criteria,<unk> o known as the Airlie House criteria, dropped the "suspected<unk> " category and added a "laboratory-supported probable<unk> " category. The Awaji criteria give abnormal EMG tests the same weight as clinical signs of LMN dysfunction in making the diagnosis of<unk> , thus making the "laboratory-supported probable<unk> " category unnecessary. The only three categories in the Awaji criteria are definite<unk> , probable<unk> , and possible<unk> . The El Escorial Revised criteria are specific for<unk> , which means that someone who meets the criteria is very likely to have<unk> ; however, they are not especially sensitive for<unk> , which means that someone who does not meet the criteria can still have<unk> . Their sensitivity is particularly poor in the early stages of<unk> . The Awaji criteria have better sensitivity than the El Escorial Revised criteria, especially for bulbar-onset<unk> . A 2012 meta-analysis found that the El Escorial Revised criteria had a sensitivity of 62.2%, while the Awaji criteria had a sensitivity of 81.1%; both sets of criteria had a specificity of about 98%. The El Escorial criteria were designed to standardize patient groups for clinical trials but are not as useful in clinical practice; possible<unk>  as described by the El Escorial criteria is almost always clinically<unk> . Differential diagnosis Because symptoms of<unk>  can be similar to those of a wide variety of other, more treatable diseases or disorders, appropriate tests must be conducted to exclude the possibility of other conditions. One of these tests is electromyography (EMG), a special recording technique that detects electrical activity in muscles. Certain EMG findings can support the diagnosis of<unk> . Another common test measures nerve conduction velocity (NCV). Specific abnormalities in the NCV results may suggest, for example, that the person has a form of peripheral neuropathy (damage to peripheral nerves) or myopathy (muscle disease) rather than<unk> . While a magnetic resonance imaging (MRI) is often normal in people with early stage<unk> , it can reveal evidence of other problems that may be causing the symptoms, such as a spinal cord tumor, multiple sclerosis, a herniated disc in the neck, syringomyelia, or cervical spondylosis. Based on the person's symptoms and findings from the examination and from these tests, the physician may order tests on blood and urine samples to eliminate the possibility of other diseases, as well as routine laboratory tests. In some cases, for example, if a physician suspects the person may have a myopathy rather than<unk> , a muscle biopsy may be performed. A number of infectious diseases can sometimes cause<unk> -like symptoms, including human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), Lyme disease, and syphilis. Neurological disorders such as multiple sclerosis, post-polio syndrome, multifocal motor neuropathy, CIDP, spinal muscular atrophy, and spinal and bulbar muscular atrophy can<unk> o mimic certain aspects of the disease and should be considered.<unk>  must be differentiated from the "ALS mimic syndromes", which are unrelated disorders that may have a similar presentation and clinical features to<unk>  or its variants. Because the prognosis of<unk>  and closely related subtypes of motor neurone disease are generally poor, neurologists may carry out investigations to evaluate and exclude other diagnostic possibilities. Disorders of the neuromuscular junction, such as myasthenia gravis (MG) and Lambert–Eaton myasthenic syndrome, may<unk> o mimic<unk> , although this rarely presents diagnostic difficulty over time. Benign fasciculation syndrome and cramp fasciculation syndrome may<unk> o, occasionally, mimic some of the early symptoms of<unk> . Nonetheless, the absence of other neurological features that develop inexorably with<unk>  means that, over time, the distinction will not present any difficulty to the experienced neurologist; where doubt remains, EMG may be helpful. Most cases of<unk> , however, are correctly diagnosed, with the error rate of diagnosis in large<unk>  clinics being less than 10%. One study examined 190 people who met the MND/ALS diagnostic criteria, complemented with laboratory research in compliance with both research protocols and regular monitoring. Thirty of these people (16%) had their diagnosis completely changed during the clinical observation development period. In the same study, three people had a false negative diagnosis of MG, which can mimic<unk>  and other neurological disorders, leading to a delay in diagnosis and treatment. MG is eminently treatable;<unk>  is not.
Amyotrophic lateral sclerosis
Botulism
Tropical ataxic neuropathy
Juvenile primary lateral sclerosis
Vascular myelopathy
Multiple system atrophy
Surfer's myelopathy
Lambert–Eaton myasthenic syndrome