How is ALS diagnosed?

ALS (amyotrophic lateral sclerosis) is a disease that is complicated to diagnose in the early stages as the condition is able to mimic a number of other neurological disorders. Some of the tests that are used to eliminate the possibility of any other conditions include:

• Magnetic resonance imaging (MRI) – An MRI is a type of scan that makes use of powerful magnetic fields as well as radio waves in order to produce extremely detailed visuals/images of the spinal cord and brain. MRIs enable doctosr to detect any spinal cord tumours or other issues that might be the cause of the symptoms, such as a herniated disc (a condition where the soft centre of the spinal disc has pushed through a small crack in the exterior casing) in the patient’s back or neck.
• Electromyogram (EMG) – This a procedure wherein the doctor will assess the health of the nerve cells and muscles by inserting an instrument known as an EMG needle electrode into certain muscles. This will then be able to evaluate the level of muscle activity when they are at rest and when they contract. If any abnormalities are detected during an EMG, this can aid the doctor in diagnosing ALS or determining whether there is a different nerve or muscle condition that is the cause of the symptoms. These findings will guide the chosen route of therapy.
• Muscle biopsy – This test is conducted if the doctor suspects that the patient has a muscle disease other than ALS. While the patient is sedated under local anaesthesia, a small part of their muscle will be removed and then sent to the lab for testing. 
• Nerve conduction velocity (NCV) test / Nerve conduction study (NCS) – This is a test that measures the speed of conduction (transmission of the impulses along a nerve) of an electrical impulse that is sent through the nerve. The nerve will be stimulated during this procedure, normally through the use of electrode patches that have been attached to the patient’s skin. This will enable to doctor to detect any nerve damage.
• Urine and blood tests – In these tests, a specialist will examine urine and blood samples in a lab in order for other causes of the symptoms to be ruled out.
• Lumbar puncture (spinal tap) – In some cases, the specialist may take a spinal fluid sample to be sent for analysis. To do this, a very small needle will be inserted directly between the two vertebrae found in the lower back, from here the needle will be used to remove some of the cerebrospinal fluid in order for it to be sent to a lab for testing. This procedure can aid in diagnosing subarachnoid haemorrhage (bleeding around the brain) or other abnormalities of the central nervous system.