When motor neurons no longer stimulate muscles normally, the affected muscles may gradually shrink.
This is called **muscle atrophy**.
You might notice:
* One hand looking thinner than the other
* Reduced muscle bulk in an arm or leg
* Increasing weakness in the same area
* Clothes fitting differently because a limb has become thinner
Muscle wasting alongside weakness and twitching is one of the neurological patterns clinicians evaluate when considering ALS. ([Mayo Clinic][2])
## 9. Muscle Stiffness
ALS can also cause increased muscle tone or stiffness.
A person may feel that:
* Legs are unusually tight
* Movements are harder to initiate
* Walking feels stiff or awkward
* Muscles jerk unexpectedly
Neurologists refer to this type of increased muscle stiffness as spasticity.
## 10. Changes in Emotional Expression
Some people with ALS develop episodes of laughing or crying that seem exaggerated or inappropriate for the situation.
Mayo Clinic also notes that inappropriate crying, laughing, or yawning may occur in ALS. ([Mayo Clinic][1])
These changes result from neurological effects rather than simply being an emotional reaction to the diagnosis.
## Does ALS Cause Numbness or Loss of Sensation?
Usually, ALS primarily affects **motor neurons**, which control movement.
Sensation such as touch, smell, hearing, and taste is generally preserved. Mayo Clinic notes that ALS usually does not affect bladder function or the senses. ([Mayo Clinic][1])
That distinction can help doctors differentiate ALS from conditions that primarily affect sensory nerves.
However, symptoms should never be interpreted in isolation.
## Does ALS Cause Pain?
Pain is generally not one of the characteristic early symptoms of ALS.
Mayo Clinic notes that pain is usually absent early in the condition. ([Mayo Clinic][1])
Pain can develop later because of muscle stiffness, immobility, joint strain, or other complications, but unexplained pain alone is not a typical early warning sign.
## === PAGE BREAK – NEXT PAGE ===
## What Causes ALS?
For most people, the exact cause is unknown.
Approximately **90% of ALS cases are sporadic**, meaning there is no obvious family history. Around 10% are familial and linked to inherited genetic variants. ([NINDS][3])
Scientists have identified multiple genes associated with ALS, including:
* C9orf72
* SOD1
* FUS
* TARDBP
Research continues into how genetics, cellular processes, and environmental factors contribute to the disease.
## How Is ALS Diagnosed?
There is no single simple blood test that confirms ALS.
Diagnosis generally involves:
