Multiple sclerosis (MS), Charcot-Marie-Tooth disease (CMT) and amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease in the US, are three neurological diseases that may at first sight resemble each other due to the similarity of their symptoms, especially motor and sensory impairment. However, they are very different indeed, both in their causes and progression mechanisms.
The purpose of this page is to clarify the main differences and similarities between these diseases, so as to better understand each of them. A detailed presentation is supplied of the characteristics of MS, CMT and ALS, as well as information on their symptoms, diagnosis, treatments and research prospects.
Did You Know ?
Professor J.-M. Charcot (1825–1893) described several neurological diseases, some of which bear his name. He was the first to describe multiple sclerosis, which is why the Belgian Charcot Foundation is named after him.
Similarities
Neurological impairment: All three diseases affect the nervous system and cause motor and/or sensory impairment.
Chronic progression: All three are chronic, progressive diseases, the symptoms of which grow worse with time.
Mobility impairment: MS, CMT and ALS can all cause muscular weakness and walking difficulties.
Impact on quality of life: All three diseases significantly affect quality of life and require multidisciplinary treatment.
Incurable to date: At this point in time, there is no cure for these diseases. The treatments are intended to manage symptoms and slow down progression.
Differences
| Multiple Sclerosis (MS) | Charcot-Marie-Tooth Disease (CMT) | Amyotrophic Lateral Sclerosis (ALS) | |
|---|---|---|---|
| Main Pathology | Auto-immune disease that attacks the myelin in the nervous system (CNS, brain and spinal cord). | Genetic disease that affects the peripheral nerves in the peripheral nervous system (PNS). | Neurodegenerative disorder that affects the motor neurones in the central (CNS) and peripheral nervous systems (PNS). |
| Cause | Auto-immune attack triggered by environmental and genetic factors. | Hereditary mutation in several genes. | Cause largely unknown; in 5-10% of cases, it is genetic. |
| Main Symptoms | Visual impairment, muscular weakness, spasticity, balance disorder, cognitive and sensory impairment, fatigue. | Distal muscular weakness (hands and feet), muscular atrophy, loss of sensation. | Progressive muscular weakness, paralysis, impaired breathing, no major cognitive impairment except in specific forms. |
| Targets in Nervous System | Central nervous system: brain and spinal cord. | Peripheral nervous system: motor and sensory nerves. | Motor neurones in central and peripheral nervous systems. |
| Progression | Relapsing-remitting, primary progressive and secondary progressive. | Slow and progressive, without flare-ups or remissions. | Swift and progressive; leads to paralysis and often death within 3 to 5 years. |
| Sensory Impairment | Frequent (numbness, tingling). | Frequent (loss of distal sensation). | Never: ALS is a purely motor disease. |
| Pain | Neuropathic pain in 50% of cases. | Slight to moderate pain in nerves or joints. | Rare, but due to immobility or muscle spasms. |
| Cognitive Impairment | Possible in advanced forms, especially executive functions. | Generally none. | Rare, except in frontotemporal ALS, which may cause cognitive and behavioural troubles. |
| Diagnosis | MRI (Magnetic resonance imagery), spinal tap, evoked potentials. | Gene testing, EMG (electromyogram), nerve conduction testing. | EMG (electromyogram), MRI (Magnetic resonance imagery) to exclude other diseases, gene testing for hereditary forms. |
| Treatments | Therapies to alter the progression of the diseases (interferons, monoclonal antibodies), symptomatic treatment. | Support care (orthoses, physiotherapy), experimental gene therapies. | Symptomatic treatments (riluzole, edaravone), palliative care, respiratory assistance. |
| Prognosis | Variable according to type, with a normal life expectancy but reduced quality of life. | Normal life expectancy, but progressive invalidity. | Reduced life expectancy, usually 3 to 5 years after diagnosis. |
Summary
MS (Multiple Sclerosis): Autoimmune disease that affects the central nervous system (CNS), with many different symptoms including motor and sensory impairment, often remitting at the beginning.
CMT (Charcot-Marie-Tooth): Genetic disease of the peripheral nervous system (PNS) that mainly causes distal muscular weakness and atrophy with sensory impairment.
ALS (Amyotrophic Lateral Sclerosis): Neurodegenerative disease that affects the motor neurones, causing swift and often fatal paralysis, but without major impairment of cognitive or sensory functions (with exceptions).
Links between Diseases
- Myelin repair: The research on myelin in MS (multiple sclerosis) may benefit the demyelinating forms of SMT (Charcot-Marie-Tooth).
- Neuroprotection: Progress in slowing down neurodegeneration in MS (multiple sclerosis) may inspire new strategies to protect the nerve fibres in CMT (Charcot-Marie-Tooth) and ALS (amyotrophic lateral sclerosis).
- Symptoms common to all three: Progress in muscle weakness, mobility impairment or fatigue management in any of these diseases could be applied to the others.
- Gene therapies: The research on gene therapies in ALS (amyotrophic lateral sclerosis) and CMT (Charcot-Marie-Tooth) could have implications for the genetic aspects of susceptibility to MS (multiple sclerosis).