What is immune neuropathy, and how does it differ from ALS?

Immune neuropathy is a disorder of the peripheral nervous system (the nerves and nerve roots) caused by a dysfunction of the immune system. In immunoneuropathies—as with ALS—slowly progressive paralysis (paresis) and muscle wasting (myopathy) can develop. Unlike ALS, immunoneuropathies are associated with abnormalities in cerebrospinal fluid analysis. Furthermore, immune neuropathies may involve individual flare-ups and periods of symptom improvement—in contrast to ALS, which typically follows a continuous course.

Immunotherapies can be treated with immunotherapies, so an improvement in symptoms can be expected as a result of the therapy (cortisone treatment, immunoglobulin therapy, immunomodulatory medications). Another difference from ALS is that immune neuropathies are not associated with signs of first-motor-neuron involvement (no spasticity, no hyperreflexia). The presence of hyperreflexia or spasticity makes an immune neuropathy highly unlikely.

Distinguishing between ALS and an immunoneuropathy can be difficult when ALS is suspected in the form of progressive muscular atrophy (PMA) and certain symptoms occur that are also characteristic of immunoneuropathies (relapsing course, electroneurographic findings). In such cases, it may be appropriate to administer immunotherapy (e.g., with immunoglobulins) to assess whether the symptoms respond to such treatment. This approach is referred to as “differential therapy” when diagnostic measures alone do not allow for a definitive distinction between ALS and an immunoneuropathy.