Neuromuscular Disorders and Multiple Sclerosis ch 50

Neuromuscular Disorders

• Neuromuscular disorders are chronic and degenerative conditions
• These disorders disrupt impulse transmission between neurons and the muscles they stimulate
• This disruption results in muscle weakness
• If respiratory muscles are affected, deadly complications such as pneumonia and respiratory failure can develop
• Common disorders within this category include multiple sclerosis (MS), myasthenia gravis, amyotrophic lateral sclerosis, and Guillain-Barré syndrome

Multiple Sclerosis (MS) Pathophysiology

• MS is a chronic, progressive, degenerative disease that affects the neurons' myelin sheath in the CNS
• The myelin sheath facilitates smooth nerve impulse transmission
• In MS, the immune system activates, causing the myelin sheath to break down
• The affected nerves become inflamed and edematous, interrupting impulses to the muscles
• Sclerosis, or scar tissue, damages the nerves as the disease progresses
• Nerve impulses can be completely blocked, causing permanent loss of muscle function

Multiple Sclerosis (MS) Etiology

• The exact cause of MS is not fully understood
• Damage to the myelin sheath is thought to be from an autoimmune process, but may relate to viral infections, heredity, and unknown factors
• Research suggests an inherited susceptibility to MS is triggered by environmental factors
• The disease typically starts between ages 20 and 50
• Women are two to three times more likely to develop MS than men, and more likely to have relapses
• Smokers and those with vitamin D deficiency have a higher MS risk

Multiple Sclerosis (MS) Signs and Symptoms

• The disease course is unpredictable with varied symptoms depending on the affected nerves
• MS is categorized based on disease progression: relapsing-remitting (RRMS), secondary progressive (SPMS), and primary progressive (PPMS)
• RRMS involves relapses with increased symptoms that typically resolve
• RRMS patients can develop SPMS where symptoms do not completely resolve after relapse
• PPMS patients do not experience relapses but neurological function worsens over time
• Symptoms vary greatly and may include muscle weakness, tingling, numbness, or visual disturbances
• Visual disturbances usually occur in one eye at a time
• Symptom onset can be slow (weeks to months) or sudden and dramatic
• MS affects many body systems and onset can be triggered/aggravated by heat, cold, fatigue, infection, and stress
• Hormonal changes after pregnancy can cause symptom onset or exacerbation
• Exacerbation and remission periods make it difficult to predict flare-ups and affected body systems
• Intense fatigue and immobility are common
• Muscle weakness or numbness can lead to accidents and falls
• Some people with MS experience muscle spasticity, bowel or bladder dysfunction, or paralysis
• Difficulty with concentration or forgetfulness can occur
• Pneumonia can occur from immobility and respiratory muscle weakness
• Death, often from respiratory infection, typically occurs 20 to 35 years after diagnosis
• Other problems include impaired hearing, nystagmus, ataxia, dysarthria, dysphagia, constipation, sexual dysfunction, and emotional changes

Multiple Sclerosis (MS) Diagnostic Tests

• Diagnosis is based on patient history, signs, and symptoms

• Analysis of cerebrospinal fluid (CSF) may show an increase in immunoglobulin G (IgG) antibodies

• Magnetic resonance imaging (MRI) of the brain and spinal cord can detect demyelination

• Evoked potential tests are used to determine slow nerve impulse transmission

• Blood tests rule out other diseases with similar symptoms

Multiple Sclerosis (MS) Therapeutic Measures

• There is currently no cure for MS, but early treatment can delay disease progression
• Some drugs slow disease progression by modifying the immune system such as inteferon therapy or immunoglobulins
• Teriflunomide and dimethyl fumarate can reduce relapses
• Steroids like adrenocorticotropic hormone (ACTH) and prednisone decrease inflammation and edema of neurons
• Anticonvulsants help relieve neuropathic pain
• Diazepam, baclofen, and tizanidine help control muscle spasms
• Parasympathetic agents like bethanechol and oxybutynin treat bladder problems
• Fatigue is treated with antidepressants or antiviral agents like amantadine
• Plasmapheresis, or plasma exchange therapy, removes the plasma component from whole blood and replaces it with fresh plasma

Myasthenia Gravis (MG) Pathophysiology

• Defined as "grave muscle weakness"
• Characterized weakness of voluntary or skeletal muscles of the body
• MG is a chronic disease of the neuromuscular junction
• A neuron typically releases acetylcholine (ACh) at the neuromuscular junction
• Receptors on muscle tissue take up ACh, producing the contractions
• The immune system is activated in MG, which produces antibodies that attack and destroy ACh receptors, preventing ACh from stimulating muscle contraction

Myasthenia Gravis (MG) Etiology

• MG is considered a chronic autoimmune process
• The precise cause may be linked to certain viruses, but other factors, such as genetic predisposition, can also play a role
• Disorders affecting the thymus gland are often associated with MG
• Can affect people of all ethnic backgrounds and genders
• Typically appears in women ages 20 to 30 and men after age 60

Myasthenia Gravis (MG) Signs and Symptoms

• MG results in progressive muscle weakness
• Muscles are the strongest in the morning but weaken throughout the day
• Muscle strength improves after rest
• Activities affected include eye and eyelid movements, chewing, swallowing, speaking, and breathing
• Common signs include drooping eyelids (ptosis) and a mask-like facial expression
• Voice may fade after long conversations
• Exacerbations can be caused by emotional or physical stress
• Major complications result from weakness of muscles used for swallowing and breathing
• Aspiration, respiratory infections, and respiratory failure are the leading causes of death
• Myasthenic crisis can be caused by undermedication and overmedication with anticholinesterase drugs can cause cholinergic crisis
• Dysphasia, weakness of the facial muscles, and potentially the patient’s ability to talk or swallow are the first signs of a clolinergic crisis
• Both myasthenic and cholinergic crises both require medical attention

Myasthenia Gravis (MG) Diagnostics

• Diagnosis is often based on a patient's history and a physical examination of symptoms
• Tests include looking upward for 2 to 3 minutes to check for increased ptosis Following a brief rest, the eyelids can be opened without difficulty
• Another test includes injecting edrophonium which leads to temporary improvement
• Another test to identify increased numbers of anti-ACh receptor antibodies are presents in 90% of patients Electromyography (EMG) can also be done to rule out other conditions

Myasthenia Gravis (MG) Therapeutic Measures

• There is no cure for MG, but treatments aim to control symptoms
• Removal of the thymus gland (thymectomy) can decrease production of ACh receptor antibodies
• Medications include anticholinesterase drugs or steroids and immunosuppressants
• A monoclonal antibody rituximab is an IV-administered medication that affects the immune system
• Plasmapheresis can remove antibodies from the patient's blood and IV immunoglobulin restores normal immune function

Amyotrophic Lateral Sclerosis (ALS) Pathophysiology and Etiology

• ALS, also known as Lou Gehrig disease, is a progressive, degenerative condition that affects motor neurons responsible for voluntary muscle control
• Upper and lower motor neurons in the brain and spinal cord degenerate and form scar tissue or die, blocking nerve impulse transmission
• Muscles atrophy, and muscle strength and coordination decrease without stimulation
• Muscle groups that control breathing and swallowing become involved
• The heart and GI tract are not affected and the ability to think and reason is unaffected by ALS
• The cause is unknown but likely due to a genetic component, and smoking and other toxins appear to increase risk

Amyotrophic Lateral Sclerosis (ALS) Signs and Symptoms

• Early symptoms are often vague and can include progressive muscle weakness and decreased coordination
• Atrophy of muscles, or the twitching of muscles, and muscle spasms can occur
• Difficulty chewing and swallowing can place the patient at risk for choking
• Inappropriate emotional outbursts of laughing and crying can occur
• Speech becomes more difficult and communication becomes limited to blinking the eyes in response to questions
• Pulmonary function may become severely compromised and require mechanical ventilation
• Other complications can include malnutrition, falls, pulmonary emboli, and heart failure

Amyotrophic Lateral Sclerosis (ALS) Diagnostics and Therapeutic Measures

• Diagnosis is primarily made on the basis of clinical symptoms
• Additional tests to rule out other conditions include a CSF analysis, electroencephalogram (EEG), nerve biopsy, nerve conduction velocity (NCV), etc
• Blood enzymes can be increased due to muscle atrophy
• Has no cure and instead treatments are palliative, aimed at supporting the patient as long as possible
• Glycopyrrolate can be administered to decrease saliva production
• Carbamazapine or phenytoin may be used for muscle cramps, while baclofen may be used for spasms
• Nonpharmacological measures such as physical therapy, massage, position changes, and diversional activities can help control pain
• Enteral feedings provide adequate nutrition

Guillain-Barré Syndrome (GBS) Pathophysiology

• A rare neuromuscular disease
• Both men and women are equally affected across all age groups, but onset is usually between 30 and 50
• An inflammatory disorder characterized by symmetrical paresis (weakness) that progresses to paralysis
• Myelin sheath of spinal and cranial nerves is destroyed by an inflammatory reaction
• Peripheral nerves are infiltrated by lymphocytes, leading to more inflammation
• Demyelination begins in the most distal nerves and ascends in a symmetrical fashion
• Remyelination is a much slower process, occuring in a descending pattern

Guillain-Barré Syndrome (GBS) Etiology

• Believed to result from autoimmune response to viral infection or vaccines
• Exact cause is unknown and viral illness typically affects the respiratory or GI system
• Occurs withing 2 weeks before the onset of neurologic symptoms
• Common organism is campylobacter jejuni

Guillain-Barré Syndrome (GBS) Signs and Symptoms

• Divided into 3 stages
• Stage 1 (onset of symptoms) can last from 24 hours to 3 weeks
• Characterized by rapid onset of muscle weakness and paralysis with no atrophy
• Reduced ability to take deep breaths or have conversations and may require intubation
• Unstable blood pressure, cardiac arrhythmias, urine retention, or paralytic ileus
• Patients will experience discomfort ranging from numbness to cramping
• Stage 2 (plateau) is the stage of severe symptoms
• Patients may become discouraged if no improvement is evident
• Occurs after 2 to 14 days
• Stage 3 (recovery) involces axonal regeneration and remyelination, which occur during this third stage
• Includes patients that recover in a few months to those that recover in few years

Guillain-Barré Syndrome (GBS) Complications

• Include repiratory failure, infection, or depression
• GBS patients are expected to recover with respiratory or oxygen support
• Monitory patient's vitals to ensure safety
• maintaining infection control practices and maximizing the patient's nutrtional status help reduce likelihood of infection problems such as skin breakdown, embolism, deep vein thrombosis, and muscle atrophy
• Patients fear they will not recover function and will need calm support

Guillain-Barré Syndrome (GBS) Diagnostics

• Lumbar puncture is preformed to obtain CSF for analysis
• CSF analyis shows regular cell count with a normal protein level
• EMG and NCV tests are preformed to evaluate nerve test
• Pulmonary function helps confirm repisratory problems

Guillain-Barré Syndrome (GBS) Therapeutics

• During inital stages, patients are dependent or completely dependent for needs
• Oxygen and mechanical ventilation may be required
• Plasma exchange may be used to remove the patient's plasma to reduce the body's immune response
• Immunoglobulin may help reduce severity of the disease
• Intensive rehabilitation and anticoagulants help patient during the recovery phase

Postpolio Syndrome

• Affects survivors of polio 20 to 40 years after recovery from infection that was caused by the poliomyelitis virus
• 40% of patients develop postpolio syndrome
• Includes weakening of muscles, fatigue, muscle weakness and atrophy, sleeping problems, joint pain, scoliosis, and respiratory compromise
• Diagnosis is by ruling out other disorders
• No interventions have been developed, but physical and occupational therapy can help

Restless Leg Syndrome (RLS)

• Sensations in the legs that cause the sufferer to constantly move the legs
• occurs at rest or at night
• Can be from imbalance of dopamine and serotonin in the brain and a heredity component
• Includes feelings of creeping, pulling, or pins and needles in the legs
• Moving the legs will temporarily relieve it

Restless Leg Syndrome (RLS) Diagnosis

• No specic tests to diagnose RLS
• HCP will order a blood test for iron deficienvy to test for other conditions that may be happening
• Treatment aims at improving symptoms by eliminating caffeine and establishing routine sleep and exercise habits
• Medications such as pramlpexole or ropinirole my be ordered to treat serum dopamine levels

Cranial Nerve Disorders

• Peripheral nerves of the brian and have 12 pairs
• Innervate areas including head, neck, and specicial sensory structures
• Causes can include tumor, infection, and unknown causes

Trigeminal Neuralgia (TN, tic douloreux)

• Damages 5th cranial nerve
• Has both sensory and motor functions
• Affects sensory portion of the nerve in areas like forhead, nose, cheek, gums, and jaw
• Symptoms include recurring episodes of intense pain and will often refrain from activities like eating to prevent pain
• Diagnosed by combined MRI and a history of symptoms
• Therapy involves carbamazepine and oxcabazepine to reduce transmission

Bell Palsy

• Inflamed facial nerve interrupting nerve impulses
• Caused by viral infections from herpes simplex, zoster, and influenza
• Symptoms can be sudden or porgress over 2 to 5 day period
• include facial nerve paralysis and the mouth being pulled ot the unaffected side
• Diagnosed by the history of onset
• Treatment goal is prevention of complications and the use of antivirals and prednisone