MOTOR NEURONS DISEASE

MOTOR NEURONS DISEASE 

Introduction📝📝📝

👉Motor neurone disease, also known as amyotrophic lateral sclerosis (ALS), occurs when specialist nerve cells in the brain and spinal cord called motor neurones stop working properly. This is known as neurodegeneration. 

👉Motor neurone disease (MND) is an uncommon condition that affects the brain and nerves. It causes weakness that gets worse over time.

👉Motor neuron diseases are a group of rare neurodegenerative disorders that selectively affect motor neurons, the cells which control voluntary muscles of the body.They include amyotrophic lateral sclerosis (ALS), progressive bulbar palsy (PBP), pseudobulbar palsy, progressive muscular atrophy (PMA), primary lateral sclerosis (PLS), and monomelic amyotrophy (MMA), as well as some rarer variants resembling ALS.

👉Motor neuron diseases affect both children and adults.

👉While each motor neuron disease affects patients differently, they all cause movement-related symptoms, mainly muscle weakness.

👉Most of these diseases seem to occur randomly without known causes, but some forms are inherited.

👉 Studies into these inherited forms have led to discoveries of various genes (e.g. SOD1) that are thought be important in understanding how the disease occurs.

👉Symptoms of motor neuron diseases can be first seen at birth or can come on slowly later in life. Most of these diseases worsen over time; while some, such as ALS, shorten one's life expectancy, others do not. Currently, there are no approved treatments for the majority of motor neuron disorders, and care is mostly symptomatic.

👉Signs and symptoms📝📝📝

👉Signs and symptoms depend on the specific disease, but motor neuron diseases typically manifest as a group of movement-related symptoms.

👉They come on slowly, and worsen over the course of more than three months. Various patterns of muscle weakness are seen, and muscle cramps and spasms may occur.

👉 One can have difficulty breathing with climbing stairs (exertion), difficulty breathing when lying down (orthopnea), or even respiratory failure if breathing muscles become involved. Bulbar symptoms, including difficulty speaking (dysarthria), difficulty swallowing (dysphagia), and excessive saliva production (sialorrhea), can also occur. Sensation, or the ability to feel, is typically not affected. Emotional disturbance (e.g. pseudobulbar affect) and cognitive and behavioural changes (e.g. problems in word fluency, decision-making, and memory) are also seen.

👉 There can be lower motor neuron findings (e.g. muscle wasting, muscle twitching), upper motor neuron findings (e.g. brisk reflexes, Babinski reflex, Hoffman's reflex, increased muscle tone), or both.

👉Motor neuron diseases are seen both in children and in adults. Those that affect children tend to be inherited or familial, and their symptoms are either present at birth or appear before learning to walk. Those that affect adults tend to appear after age 40. The clinical course depends on the specific disease, but most progress or worsen over the course of months.

Patterns of weakness :-

👉Various patterns of muscle weakness occur in different motor neuron diseases.

 👉Weakness can be symmetric or asymmetric, and it can occur in body parts that are distal, proximal, or both... According to Statland et al., there are three main weakness patterns that are seen in motor neuron diseases, which are

👉Asymmetric distal weakness without sensory loss (e.g. ALS, PLS, PMA, MMA)

👉Symmetric weakness without sensory loss (e.g. PMA, PLS)

👉Symmetric focal midline proximal weakness (neck, trunk, bulbar involvement; e.g. ALS, PBP, PLS)

Lower and upper motor neuron findings:-

Motor neuron diseases are on a spectrum in terms of upper and lower motor neuron involvement. Some have just lower or upper motor neuron findings, while others have a mix of both. Lower motor neuron (LMN) findings include muscle atrophy and fasciculations, and upper motor neuron (UMN) findings include hyperreflexia, spasticity, muscle spasm, and abnormal reflexes.

👉Pure upper motor neuron diseases, or those with just UMN findings, include PLS.

👉Pure lower motor neuron diseases, or those with just LMN findings, include PMA.

👉Motor neuron diseases with both UMN and LMN findings include both familial and sporadic ALS.

Causes📝📝📝:-

👉Most cases are sporadic and their causes are usually not known.

👉It is thought that environmental, toxic, viral, or genetic factors may be involved.

Diagnosis📝📝📝:-

👉Differential diagnosis can be challenging due to the number of overlapping symptoms, shared between several motor neuron diseases. Frequently, the diagnosis is based on clinical findings (i.e. LMN vs. UMN signs and symptoms, patterns of weakness), family history of MND, and a variation of tests, many of which are used to rule out disease mimics, which can manifest with identical symptoms.

👉Please refer to individual articles for the diagnostic methods used in each individual motor neuron disease.

Test for diagnosis :-

👉Cerebrospinal fluid (CSF) tests: Analysis of the fluid from around the brain and spinal cord could reveal signs of an infection or inflammation.

👉Magnetic resonance imaging (MRI): An MRI of the brain and spinal cord is recommended in patients with UMN signs and symptoms to explore other causes, such as a tumor, inflammation, or lack of blood supply (stroke).

👉Electromyogram (EMG) & nerve conduction study (NCS): The EMG, which evaluates muscle function, and NCS, which evaluates nerve function, are performed together in patients with LMN signs.

👉Tissue biopsy: Taking a small sample of a muscle or nerve may be necessary if the EMG/NCS is not specific enough to rule out other causes of progressive muscle weakness, but it is rarely used.

TREATMENT 📝📝📝:-

👉There is no cure for motor neurone disease and no treatment will significantly alter its course. Medications may be prescribed to control involuntary muscle twitching, muscle cramps and excess saliva. However, treatment essentially focuses on retaining function and quality of life and providing comfort.

👉A disease-modifying drug called riluzole (Rilutek), which has the potential to modestly prolong survival in some patients, is available in New Zealand. Riluzole is funded for people who meet certain criteria and can only be prescribed by a specialist, usually a neurologist.

👉The progressive nature of the condition means that most people will eventually require full time nursing care. When breathing becomes too difficult, a mechanical ventilator may be required to maintain breathing. While the use of a ventilator can prolong life and improve sleep, it will not alter the course of the condition, and many people with motor neurone disease therefore choose not to use ventilators for lengthy periods.