Skip to Content

Which areas of the body are affected by ALS first?

ALS, also known as Lou Gehrig’s disease, is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord. It causes the nerves to gradually lose function, leading to muscle weakness, paralysis, and eventually death. ALS is a rare disease, affecting around 5 cases per 100,000 people globally each year. The initial symptoms of ALS can be quite subtle and occur in different parts of the body depending on which muscles are affected first. Identifying the early signs and which areas are impacted first is important for getting a prompt diagnosis and starting treatment as soon as possible.

What is ALS?

ALS stands for amyotrophic lateral sclerosis. It is a progressive disease marked by the death of neurons that control voluntary muscles. “Amyotrophic” refers to the loss of muscles due to the degeneration of lower motor neurons. “Lateral sclerosis” refers to the hardening of lateral columns of the spinal cord due to degeneration of upper motor neurons. Over time, as motor neurons die, the brain loses its ability to initiate and control muscle movement. Early symptoms include tripping, dropping things, abnormal fatigue, slurred speech, muscle cramps and twitches. The cause is unknown in 90 to 95 percent of cases. About 5 to 10 percent of cases are inherited.

Which Parts of the Body are Affected First?

The first symptoms of ALS often involve isolated muscle weakness or cramping in specific regions. The parts of the body impacted early in ALS depend on which motor neurons are damaged first. Generally, ALS begins in one of the following areas:

Arms and Legs

For many people with ALS, the first sign is weakness or wasting in the arms or legs. This asymmetry is characteristic of ALS – symptoms typically start in one limb before progressing to other areas. Early arm symptoms may include:

  • Tripping or dropping things
  • Difficulty with fine motor skills like buttoning clothes
  • Muscle cramps, twitches, or spasms
  • Weak grip strength

Leg symptoms often begin with a condition called “foot drop” where it becomes difficult to lift the front of the foot. This causes tripping, dragging the foot, or slapping down the foot while walking. Other early leg symptoms include:

  • Stumbling or falling
  • Abnormal fatigue in the legs
  • Cleat dragging when walking
  • Toe walking

Bulbar Region

The bulbar region involves the motor neurons that stimulate the muscles for chewing, swallowing, and speaking. Initial symptoms in this area may include:

  • Slurred, nasal speech
  • Stuttering
  • Excessive saliva/drooling
  • Choking on food or liquids
  • Fatigue when chewing or swallowing

If ALS begins in the bulbar area, it is called “bulbar onset ALS”. This form progresses rapidly and has a worse prognosis than limb onset.

Respiratory System

In some ALS cases, the first symptom is difficulty breathing. Early respiratory signs include:

  • Shortness of breath
  • Labored or shallow breathing
  • Frequent sighing
  • Noticeable breathlessness during conversation
  • Fatigue
  • Morning headaches
  • Poor sleep or daytime sleepiness

When breathing muscles weaken, it impairs oxygen intake and carbon dioxide removal. Respiratory failure is the most common cause of death for ALS patients.

Head and Neck

Rarely, initial ALS symptoms may show up as muscle twitches or tightness in the head and neck. Early facial symptoms include:

  • Slurred speech
  • Impaired swallowing
  • Excessive drooling
  • Jaw cramping
  • Uncontrolled laughter or crying
  • Head drop or neck weakness

How Does ALS Progress?

After the initial symptoms, ALS spreads to other unaffected areas. People with arm or leg onset will notice weakness spreading to the other limbs. Bulbar onset ALS proceeds to impact the arms and legs. Generally, muscle wasting and loss of function grows progressively worse over 2-4 years. Patients eventually lose the ability to walk, use their arms and hands, speak, swallow, and breathe without intervention.

ALS progresses through the body in the following stages:

Stage 1

Isolated muscle weakness in one limb or region – may be barely noticeable at first. Gradually worsens over a period of months. Functionality is not significantly impaired.

Stage 2

Weakness and wasting spreads to other areas like the opposite limb. Increased difficulty with motor functions like walking, grip strength, or swallowing. Moderate impact on daily activities.

Stage 3

Significant muscle weakness throughout most of the body. Impaired mobility – walking only short distances or needing assistance. Slurred speech. Difficulty breathing when lying down. Unable to do most daily activities without help.

Stage 4

Near-total loss of voluntary muscle function. Paralysis in legs and arms. May retain some finger movement. Speech indistinct or lost. Requires wheelchair and respirator. 24/7 care needed.

How is ALS Diagnosed?

There is no single test that can definitively diagnose ALS. Doctors assess the symptoms and rule out other possible conditions through this process:

  • Medical history – Looking for family history of ALS, risk factors like smoking, and onset of weakness.
  • Physical exam – Testing reflexes, muscle tone, strength, breathing, and swallowing.
  • Electromyography (EMG) – Measures electrical activity of muscles and nerves. Can confirm if nerves are deteriorating.
  • MRI – Provides images of the brain and spinal cord to rule out other disorders.
  • Blood and urine tests – Helps exclude issues like thyroid problems, autoimmune disease, and vitamin deficiencies.

Patients may see a neurologist over several months to document the progression of symptoms before confirming an ALS diagnosis.

Progression of ALS by Site of Onset

Site of Onset Early Symptoms Average Time to Death
Arm Weak grip, muscle twitches in arms 2.7 years
Leg Tripping, falling, foot drop 3.5 years
Bulbar Slurred speech, excess saliva 2 years
Trunk Difficulty breathing 1.4 years

As shown in the table, bulbar onset and respiratory onset ALS have the quickest progression and shortest survival times on average. Limb onset ALS has a more gradual course.

Risk Factors

The exact cause of ALS is still unknown. Research suggests several risk factors can increase a person’s likelihood of developing the disease:

  • Age – Most people with ALS are between 40 and 70 years old.
  • Genetics – About 5-10% of ALS cases are inherited. Having a close relative with ALS raises your risk.
  • Sex – ALS is slightly more common in males than females.
  • Race – Whites have a higher incidence rate compared to Blacks, Asians, and Hispanics.
  • Smoking – Tobacco use is associated with increased ALS risk.
  • Military Service – Veterans have a 1.5 to 2 times greater risk of ALS.
  • Athletes – People who engage in intense physical activities may be more prone to ALS.
  • Lead exposure – Past lead exposure from drinking water, paint, batteries, etc may be a possible risk factor.

While these correlations exist, most cases of ALS occur in people with no known risk factors.

Treatment and Progression

There is currently no cure for ALS. The only FDA-approved drug for ALS is riluzole, which may modestly slow disease progression. Other treatments aim to manage symptoms and improve quality of life:

  • Medications – Muscle relaxants, morphine, and antidepressants help control pain, cramps, and mood changes.
  • Physical therapy – Stretching and range of motion exercises keep muscles active.
  • Speech therapy – Devices can assist with communication when speaking becomes difficult.
  • Nutritional support – Feeding tubes provide nutrition when swallowing is impaired.
  • Breathing assistance – Ventilators and cough assist devices help with respiratory decline.

Despite treatment, ALS causes progressive paralysis and leads to death typically within 2-5 years of diagnosis. About 20% of patients live 5 years after being diagnosed, and 10% survive more than 10 years. Managing symptoms, nutrition, and respiratory function can help extend and improve quality of life.

Supporting Someone with ALS

Receiving an ALS diagnosis is emotionally devastating and life changing. As a loved one or caregiver, you can provide valuable physical, emotional, and social support:

  • Learn about ALS so you understand what to expect as it progresses.
  • Be an advocate in seeking treatment, equipment, and access to services.
  • Help the person conserve their energy – assist with tasks or modify activities.
  • Provide reassurance and a listening ear when they need to talk or vent.
  • Encourage engagement in hobbies adapted to their abilities.
  • Offer respite care if you need a break from caregiving duties.
  • Connect them with ALS support groups and grief counseling.

People with ALS need compassion and help maintaining the highest possible quality of life. With commitment from loved ones, meaningful living is possible despite the losses caused by ALS.


ALS causes progressive paralysis by attacking nerve cells that control muscles. Initial symptoms occur in localized areas like the arms, legs, neck, or respiratory system. Identifying the early signs of weakness allows prompt diagnosis and treatment to maximize function for as long as possible. While ALS inevitably worsens over 2-5 years, supportive care improves quality of life. Researchers continue seeking more effective treatments and ultimately a cure for this devastating disease.