Neuropathy, Myopathy, and NMD Flashcards
What is a Mononeuropathy?
A single, major nerve is involved with sensory or motor deficits related to its anatomical distribution
Wha are the 2 most common causes of mononeuropathies?
Trauma or Compression
Common cause of Ulnar Mononeuropathy?
Leaning or falling on the elbow
Common cause of Peroneal Mononeuropathy?
Injury to the lateral knee
Carpal Tunnel Syndrome
Describe the pathophysiology
If there is inflammation or swelling of the flexor tendons in the carpal tunnel, they can compress the median nerve and cause pain
May also be caused by fluid retention in pregnancy
Carpal Tunnel Syndrome
Clinical Symptoms
Tingling numbness of hand (thumb, index, middle, 1/2 ring finger)
Thenar weakness and atrophy in very severe cases
Carpal Tunnel Syndrome
Treatment
Local rest
Anti-inflammatories
Splinting
Surgical decompression of the nerve
Describe Wallerian degeneration of nerves
Occurs at sites of severe nerve injury
Injury involves myelin and axons distal to the point of injury
Do nerves regenerate?
CNS neurons are not good at regenerating, but PNS neurons may regenerate. Likelihood of regrowth is based on distance needed to travel and the degree of injury sustained
What is a polyneuropathy?
Disorder of multiple, major and small nerves
Characterized by an early sensory loss in distal limbs
Polyneuropathy
Clinical Symptoms
Spontaneous tingling
Pins and needles = Paresthesia
Unpleasant stimulation from non-painful stimuli = Dysesthesia
Distal limb weakness and atrophy
Early loss or decrease of muscle stretch reflexes
What are two general big causes of Polyneuropathy?
Axonal degeneration (more common)
Demyelination
How are axonal degeneration and demyelination discriminated on nerve conduction studies?
Axonal degeneration – amplitude of waves are reduced
Demyelination – slowing of the nerve conduction
What is EMG testing?
Needle electromyography
Electrical activity of muscles within individual motor units is assessed for denervation, reinnervation, or muscle disease
When are nerve biopsies performed?
Rarely. Only for significant neuropathy and typically only done for sensory nerves.
The patient is left with numbness after the biopsy
Polyneuropathy
Treatment
Address underlying causes (diabetes, alcohol)
Orthotic devices – improve ambulation
Physical therapy
Meds to improve paresthesia or dysesthesia
Guillan Barre Syndrome
Clinical Symptoms
Ascending, areflexic paralysis
Acute polyneuropathy and weakness progressing quickly and at its worst by 4 wks
Guillan Barre Syndrome
What often precedes this syndrome? Describe the pathology.
Acute viral respiratory infection precedes the syndrome 50% of the time.
Misdirection of immune system to attack normal peripheral nerve myelin
Get inflammation and demyelination of the peripheral nerves or roots
Guillan Barre Syndrome
Diagnosis
Evidence of demyelination seen on EMG (slowing of conduction)
Elevated protein in CSF, few if any WBCs
Guillan Barre Syndrome
Prognosis and Treatment
Good prognosis with medical treatment
Plasmapheresis or IVIG may shorten illness and hasten recovery
List some potential causes of Chronic Acquired Polyneuropathies
Diabetes Hypothyroid Uremia Cancer Myeloma Rheumatoid arthritis Lupus Nutritional defects (Vit B) Infection (leprosy) Toxins (alcohol, lead)
Hereditary Neuropathies
Clinical Symptoms
Onset usually in childhood
Distal sensorimotor deficits
Little/no paresthesia or dysthesia
May affect skeletal development (scoliosis, hammertoes, pes cavus)
What is a myopathy?
Primary disease of muscle
What is the first sign of myopathy?
PROXIMAL limb weakness and atrophy (shoulder and hip)
Symptoms of Myopathy
Weakness
Fatigue, maybe with cramping
Proximal limb weakness (shoulders and hips)
Late loss of reflexes (after significant atrophy)
Intact sensation
Myopathy
Diagnostic Methods
Review family history
Serum enzymes (CK) often elevated
EMG demonstrates muscle disorder
Muscle biopsy
What is Polymyositis?
Inflammation and weakness of multiple muscles
What are the causes of Polymyositis?
Viral infection
Drug reaction
Autoimmune
Polymyositis
Diagnosis
EMG testing
Presence of inflammation and muscle fiber necrosis on muscle biopsy
Polymyositis
Treatment
Immunosuppression (corticosteroids)
Polymyositis
Clinical Symptoms
Proximal weakness (like a myopathy)
Rash around eyes or fingers
What is Muscular Dystrophy?
Hereditary myopathy of variable progression and severity
Duchenne’s Muscular Dystrophy
What is the inheritance? What is the pathological defect?
X linked inheritance
Absence of dystrophin (a crucial structural protein in muscle)
Duchenne’s Muscular Dystrophy
Clinical Symptoms
More common in boys (X linked)
Proximal weakness
Calf pseudohypertrophy from muscle replaced by fat
Cardiorespiratory death by 3rd decade
What is Gower’s Maneuver?
Have pt lay on floor belly down
Tell them to get up –> weak hip girdle causes them to crawl up on hands and legs before being able to rise
What is Motor Neuron Disease (MND)?
Disorders, sometimes hereditary, where degeneration of UMNs and LMNs occur with varying severity and progression rate
Spinal Muscular Atrophy
What cells are involved?
MND with Anterior horn involvement
Spinal Muscular Atrophy
Clinical Symptoms
LMN signs of weakness, atrophy, areflexia, fasciculations
Spinal Muscular Atrophy
Infantile form is…
Werdnig Hoffman
Terminal condition due to rapid development of diffuse weakness
Amyotrophic Lateral Sclerosis
Describe the pathology
Progressive degeneration of ALL motor neuron subgroups (UMNs and LMNs)
Amyotrophic Lateral Sclerosis
Prognosis and Treatment
Worst prognosis (50% dead within 3 years)
No curative treatment, but Riluzole (glutamate antagonist) may prolong survival by months
Amyotrophic Lateral Sclerosis
Clinical Symptoms
Start –> Regional weakness and atrophy of limb, which spreads and becomes bilateral
Diffuse fasciculations
Hyperreflexia
Spasticity
Babinski sign positive
Weakness affecting speech, swallowing, chewing, breathing
