Amyotrophic Lateral Sclerosis (ALS) is a condition which can be difficult to initially diagnose. ALS diagnosis is based on clinical presentation, with supportive data from electro-diagnostic, imaging, and laboratory studies. As well as there being no cure for ALS, there is also no single diagnostic test that can definitely diagnose the condition since it shares many common symptoms with other neurological diseases.
However, the presence of both upper and lower motor neuron symptoms suggests that someone might be suffering from this particular neurodegenerative disease. Moreover, individuals might benefit through seeking a second neurological opinion since a definitive initial diagnosis is not always possible. For a complete ALS diagnosis, clinical tests need to be undertaken to rule out other neurological diseases based on the symptoms shown by the patient.
The diagnosis of Amyotrophic Lateral Sclerosis is based on the period of observation to track the progression of the symptoms in the patient and the clinical tests conducted to help in ruling out other diseases by the doctor. Such observation of symptoms in the patient can take up to a year, resulting in a diagnosis spread over twelve to fourteen months. There are several other diseases with similar symptoms to ALS and many of them are treatable. For this reason, the ALS Association recommends that a person diagnosed with ALS should seek a second opinion from an expert who has experience in diagnosing and treating people with ALS.
For the diagnosis of ALS, some specific criteria has been developed, known as El Escorial criteria. According to the El Escorial criteria, by the World Federation of Neurology (WFN), conditions for the diagnosis of ALS include signs of degeneration of the upper motor neurons (UMN) and lower motor neurons (LMN) in the spinal cord, brainstem and in the brain respectively, the progressive spread of symptoms within a region, or to other regions of the patient’s body. Moreover, criteria also includes lack of evidence of other disease processes that could explain the symptoms. Motor neurons are nerve cells whose cell body is situated in the spinal cord and whose fiber (axon) projects outside the spinal cord in order to control the muscle movement.
There is need for a thorough medical, family history and physical examination for a neurological workup, including simple tests of muscle and nerve function. A full and complete diagnostic test for ALS includes procedures such as Electromyography (EMG), Nerve Conduction Velocity (NCV), X-rays including Magnetic Resonance Imaging (MRI) and others.
Electromyography (EMG) helps in assessing the electrical activity in the muscle. For the diagnosis of ALS, abnormal EMG results can help to confirm LMN degeneration. Abnormalities in the muscles observed through EMG can help the doctors to diagnose ALS by determining if one has a different muscle or nerve condition that may be causing the symptoms. The test measures the signals that run between the nerves and the muscles and the electrical activity inside the muscles to identify whether there is a pattern consistent with ALS.
A Nerve Conduction Velocity (NCV) study excludes disorders that affect the peripheral nerves and just measures the capacity of a nerve to transmit an electrical signal to other body parts. Nerve conductions studies help in understanding the ability of the nerve to send impulses to muscles in all parts of the body. It helps to ultimately determine whether one has any kind of nerve damage of muscle disease.
Diagnostic imagings including Magnetic Resonance Imaging (MRI), is used to produce images of the brain and spinal cord using radio waves and magnetic field to assist in the diagnosis of the disease. It is a non-invasive procedure the produces detailed images for diagnosis. Although ALS patients usually reflect normal MRI scans of the spinal cord and the brain, however, this can help in revealing other treatable causes behind the symptoms, like syringomyelia (a cyst in the spinal cord) or cervical spondylosis which impacts the spine in the neck. It can also help in diagnosing spinal cord tumors, herniated disks in the neck or other causes behind the symptoms.
Muscle or nerve biopsies are performed in very few and rare cases. They involve a process of removing a small section of muscle from the patient using local anesthesia which is then examined for abnormalities. A spinal tap also known as lumbar puncture is conducted to exclude the inflammatory nerve conditions. This process involves a test of the fluid surrounding the spinal cord by inserting a needle into the back between the two lower vertebrae and removal of some cerebrospinal fluid of spinal cord by a specialist for testing in the laboratory. Some other tests conducted include a Myelogram of the cervical spine and a thorough neurological examination.
Laboratory tests of the person’s symptoms can help the physician analyse blood and urine samples to eliminate the possibility of other diseases. Blood and urine testing for high resolution serum protein electrophoresis, thyroid and parathyroid functioning can help in the diagnosis of ALS.
Tests should be conducted for infectious diseases such as Human Immunodeficiency Virus (HIV) and Human T-cell Leukemia Virus (HTLV), Lyme disease, polio and West Nile, which can cause symptoms similar to the ones as experienced in Amyotrophic Lateral Sclerosis. Other neurological disorders, such as multiple sclerosis, multifocal motor neuropathy, spinal and bulbar muscular atrophy can also mimic certain symptoms of the disease and should be considered by the physician during the diagnosis process. In few cases, muscle cramps and fasciculations may occur and since the symptoms resemble ALS in initial stages of diagnosis, it is important to get a second opinion from a neurologist.
Different treatments exist which can help in extending the length and quality of life of patients with ALS. Thus, presently, ALS is being diagnosed using El Escorial criteria and through detailed medical, family history and physical examination by the physician. Research is being undertaken to better understand how ALS patients can live a better life with more enhanced diagnosis and treatment.