Pain and tingling in the hand is typically present in CTS and absent from MMA; loss of function presents differently; with careful electrophysiological study and neurological exams the two are distinguished. In early stages, ALS, SCA, and MMA, presentation may be similar. Both CSA and ALS ultimately have more extensive symptoms. MMA is more prevalent in young people while ALS and CSA are more common in older populations. With ALS, hand symptoms usually more commonly both proximal and distal vs in MMA mostly distal only, and with ALS fasciculations (twitching) are often present in upper extremities, but rarely in MMA. MMA is usually eliminated from consideration if disability expresses itself in more than one extremity or in lower extremities (legs), but symptomatic absence may not rule out ALS for three to five years after initial onset. Electrophysiological texts and reflex tests tend to yield different results, but interpretation is at times subjective. Treatment
At present there is no cure for MMA. The impact on the affected individual ranges from minimal to significant depending on the extent of the weakness. Physical and occupational therapies include muscle strengthening exercises and training in hand coordination. Early use of a cervical collar is increasingly encouraged as therapeutic for arresting further compression of the cervical spinal cord. Spinal surgery on patients with more advanced symptoms has met with reported success, but is still regarded as experimental. Prognosis
The symptoms of MMA usually progress slowly for two to five years and then remain stable for many years.
Proposed diagnostic criteria:

Distal predominant muscle weakness and atrophy in forearm and hand
Involvement of the unilateral upper extremity almost always all the time
Onset between the ages of 10 to early 20s
Insidious onset with gradual progression for the first several years, followed by stabilization
No lower extremity involvement
No sensory disturbance and tendon reflex abnormalities
Exclusion of other diseases (e.g., motor neuron disease, multifocal motor neuropathy, brachial plexopathy, spinal cord tumors, syringomyelia, cervical vertebral abnormalities, anterior interosseous, or deep ulnar neuropathy)
A neurological exam can suggest different motor neuron diseases (such as MMA), but to more confidently distinguish MMA from the diseases it mimics, advanced diagnostic tools are called for. These include exam tools such as magnetic resonance imaging (MRI), and electromyography (EMG) and nerve conduction velocity (NCV) tests. An MRI examination of the neck would typically reveal—for a positive MMA diagnosis—some constriction of the cervical cord and an abnormal forward extension of the neck, ("loss of cervical lordosis"); pressure by the dura on the nerve cord apparently causes the flattening / narrowing. An EMG test reveals loss of the nerve supply, or denervation, in the affected limb without a conduction block (a nerve blockage restricted to a small segment of the nerve).In early stages of the disease MMA may be confused for amyotrophic lateral sclerosis (ALS), cervical spondylotic amyotrophy (CSA), and other challenging neurological diseases, as well as conditions that are minor but that call for very different treatments, such as advanced carpal tunnel syndrome (CTS). Symptoms somewhat differ.