Understanding ALS: Symptoms, Misdiagnosis, & Diagnosis

A comprehensive overview of ALS progression, diagnostic challenges, and clinical identification.

đź’ˇ ALS Symptoms and Progression

Image of muscle weakness and twitching in an arm

Initial and Very Early Symptoms

Muscle weakness and twitching are hallmark early symptoms of ALS. While occasional muscle twitches are typically benign, persistent fasciculations or muscle cramps that linger or recur over several weeks should prompt a medical evaluation. It’s crucial to be vigilant about subtle changes in muscle strength, coordination, and even slight alterations in speech, chewing, or swallowing abilities.

As mentioned earlier, these seemingly minor shifts could be early indicators of ALS progression. However, it’s important to note that chronic muscle twitching without other muscle-related symptoms, especially if experienced for years, may not necessarily signal ALS. Some individuals are simply more prone to persistent muscle twitches. Nonetheless, any new or concerning muscle symptoms, particularly when accompanied by weakness or functional changes, should be assessed by a healthcare professional to rule out ALS or other neurological conditions.

Persistent muscle weakness, twitching, or cramps lasting several weeks should prompt a medical evaluation to rule out ALS or other neurological conditions.

Changes in motor function and coordination are often among the earliest signs of ALS. Individuals may notice subtle alterations in their ability to perform routine tasks, such as buttoning clothes or tying shoelaces. These difficulties can manifest as frequent tripping or falling, indicating a decline in balance and coordination.

As the disease progresses, muscle weakness typically becomes more pronounced, often starting on one side of the body, affecting either an arm or a leg. This asymmetrical weakness is a hallmark of early ALS. Additionally, people may experience changes in their speech, such as slurred words or slower speech patterns, which are indicative of the disease’s impact on bulbar muscles. It’s crucial to note that these symptoms can develop gradually and may initially be mistaken for normal aging, making early recognition challenging. This underscores the importance of staying vigilant and seeking professional medical advice when persistent changes are noticed.

Speech and Swallowing Difficulties (Bulbar Symptoms)

These are often among the earliest manifestations of ALS, particularly in bulbar forms of the disease. These symptoms can be crucial indicators for accurate diagnosis and early intervention. Voice changes may include harshness, strain-strangled quality, breathiness, tremor, and pitch abnormalities. In some cases, features resembling spasmodic dysphonia have been observed.

Swallowing problems typically progress in a predictable pattern, beginning with difficulties managing tough textures, fragmented foods, and thin liquids. As the disease advances, patients may experience severe challenges controlling liquids during swallowing and maintaining adequate nutritional intake. The progression of dysphagia in bulbar ALS has been categorized into five stages, ranging from normal eating habits to complete inability to take food orally.

Notably, laryngeal dysfunction can manifest as failure of the larynx to move properly during swallowing, increasing the risk of aspiration. These bulbar symptoms often result from the involvement of multiple cranial nerves, including the trigeminal, facial, hypoglossal, glossopharyngeal, and vagus nerves. The complex interplay of spasticity, flaccidity, and compensatory strategies contributes to the variability of phonatory and swallowing symptoms observed among ALS patients. (ALS United)

More Pronounced Symptoms

  • Muscle fasciculations and cramps
  • Muscle wasting
  • Asymmetric limb weakness
  • Slurred nasal or hoarse speech
  • Difficulty with swallowing
  • Tongue weakness
  • Shortness of breath

🚨 Common Misdiagnoses of ALS

Image showing a diagnostic puzzle or overlapping symptoms, representing misdiagnosis

Misdiagnosis of ALS is not uncommon, with studies reporting rates between 3.9% and 8%. Common conditions mistaken for ALS include structural spinal pathology, hereditary spastic paraplegia (HSP), and multifocal motor neuropathy (MMN). Cervical spondylosis and spinal stenosis can mimic ALS symptoms, highlighting the importance of thorough spinal imaging. HSP, characterized by symmetric lower extremity spasticity, may be misdiagnosed as ALS, especially in cases with long symptom duration. MMN, an immune-mediated neuropathy, can present similarly to ALS but often responds to immunoglobulin therapy. Other potential misdiagnoses include multiple sclerosis, Parkinson’s disease, and spinal muscular atrophy.

Notably, lack of disease progression is the most common reason for diagnostic reconsideration. Atypical features that should prompt consideration of alternative diagnoses include symmetric findings, disease duration greater than 2 years at presentation, young age at onset (less than 50), and pain. The complexity of ALS diagnosis underscores the importance of longitudinal evaluation and continual reassessment of patients’ clinical presentations.

🔬 The Diagnostic Process for ALS

Image of a neurologist consulting with a patient, with medical equipment in the background

Have a Neurological Exam

The diagnosing ALS process begins with an examination by a neurologist. This will include a detailed review of the patient’s family, work, and environmental history. During the exam, the neurologist will look for typical features of ALS, such as:

  • Muscle weakness, which is often only on one side of the body, such as one arm or one leg.
  • Vocal changes, especially slurred words or slow speech.
  • Muscle changes affecting the mouth, tongue, chewing, and swallowing functions.
  • Lower motor neuron (LMN) features, such as muscle shrinkage or twitches. These twitches are called fasciculations and may occur when muscles contract without full control from the nerve cells.
  • Upper motor neuron (UMN) features, such as hyperactive reflexes and muscle spasticity, which is a type of tightness and rigidity of the muscles
  • Emotional changes resulting in the loss of some control of emotional responses, such as uncontrollable crying or laughing.
  • Changes in thinking, such as loss of good judgment or common social skills
  • Problems in verbal fluency and word recognition abilities. These symptoms are less common or may be present but not readily noticeable.
  • Pain, loss of sensation, or extra-pyramidal rigidity, which is a different type of muscle rigidity that is frequently seen in Parkinson’s type disorders

Undergo Diagnostic ALS Testings

The next step to diagnose ALS often involves a series of tests. These typically include an MRI (magnetic resonance imaging) of the neck, and sometimes of the head and lower spine, along with an EMG (electromyography) which tests nerve conduction, and a series of blood tests. Sometimes urine tests, genetic tests, or a lumbar puncture (also called a spinal tap) are also necessary.

Electromyography (EMG)

The EMG is a very important part of the diagnostic process for ALS. In the first part of the EMG, small electric shocks are sent through the nerves to measure their conduction speed and detect any potential nerve damage. This phase determines whether the individual has “nerve block,” or if sensory nerves are affected. In the second part, a fine needle tests the electrical activity of specific muscles.

MRI

An MRI is a painless, non-invasive procedure that offers a very detailed picture of the spinal cord and brain. It helps rule out conditions like pressure on the spinal cord or major nerves (such as from a herniated vertebral disk), multiple sclerosis, tumors, bony abnormalities, vascular changes, and strokes.

Lab Tests

Blood and Urine Tests: Used to look for evidence of other diseases with similar symptoms (e.g., thyroid, B12 deficiency, HIV, hepatitis, auto-immune diseases, cancers). Creatine kinase (CK) is also measured. Specialized blood tests (autoimmune antibody, anti-GM1) and heavy metal screening may be done.

Genetic Tests: Performed in rare cases, especially with family history of ALS or for conditions like juvenile spinal muscle atrophy.

Spinal Tap (Lumbar Puncture): May be required for unusual ALS features or absence of abnormal reflexes/spasticity, to examine cerebrospinal fluid.

Muscle Biopsy: Rarely needed for uncommon patterns of weakness, pain, or very high CK levels to rule out muscle-specific diseases.

Receive a Diagnosis

Once these tests have been completed, the neurologist may be able to tell whether an individual has ALS. Sometimes, not all of the symptoms and findings that are required to make the ALS diagnosis are present, especially in the early phase of the disease. In this case, the neurologist will repeat the physical and neurological exams and the EMG at a later date to look for changes over time. (Healey center)

The diagnosis often requires evidence of progression and involvement of both Upper Motor Neuron (UMN) and Lower Motor Neuron (LMN) signs across multiple body regions to confirm ALS and differentiate it from other conditions.