Can ALS be “mistaken” for other diseases?

In general, ALS can be diagnosed using simple methods. These include the findings from a physical examination and additional diagnostic tests (usually including EMG, neurography, MRI, cerebrospinal fluid analysis, and laboratory tests). In certain cases, it can be difficult to distinguish ALS from other neurological disorders that are also associated with paralysis (paresis), muscle wasting (myopathy), or muscle stiffness (spasticity).

Distinguishing ALS from other diagnoses (differential diagnosis) can be complex if not all typical features of ALS are present (combined presence of paresis, atrophy, hyperreflexia, and spasticity) and only isolated symptoms are present (e.g., exclusively myatrophy and paresis). Diagnostic challenges also arise when the course of the disease (acute onset, rapid progression, or a particularly slow rate of progression) is unusual or when symptoms are present that are not characteristic of ALS (e.g., pain or sensory disturbances).

In these cases, distinguishing ALS from other neurological disorders can be difficult and may require special diagnostic measures. Disorders that may present with symptoms similar to those of ALS include spinal muscular atrophy (SMA), spastic spinal paralysis (SSP), motor neuropathies (immune neuropathies, including multifocal motor neuropathy), cervical myelopathy, and certain forms of multiple sclerosis (MS).