PNS disease Flashcards
How many pairs of nerves are there in the PNS?
31
Explain which of the 31 pairs of spinal nerves are.
Cervical nerves (8)
thoracic nerves (12)
lumbar nerves (5)
sacral nerves (5)
coccygeal nerves (1)
What are the afferent and the efferent cells?
Afferent cells - sensory nerves that transfer electrical signals from the muscle to the spinal cord
Efferent cells - motor nerves that transfer electrical signals from the spinal cord to the muscle to take actions
What is the peripheral nervous system divided into?
somatic system - afferent & efferent nerves
Autonomic system sympathetic & parasympathetic
What is the sympathetic and parasympathetic nervous system?
Sympathetic nervous system:
- increase heart rate
- increase blood pressure
- decrease digestion
- maximized blood flow
# Flight or Flight response
Parasympathetic
- decrease heart rate
- increase digestion
# Rest & digest response
define these neuropathies
- mononeuropathy
- multiple mononeuropathy
- polyneuropathy
- plexopathy
- radiculopathy
- mononeuropathy –> affects one nerve
- multiple mononeuropathy –> affects several discrete nerves
- polyneuropathy –> affects multiple nerves that spread around
- plexopathy –> affects a bundle of nerves
- radiculopathy –> affects the site where the nerves leave (i.e. neck/spine)
types of peripheral neuropathy
mononeuropathy
polyneuropathy
mononeuropathy multiplex
acquired demyelinating polyneuropathy causes
Demyelination (damage to the myelin sheath), which slows nerve conduction
symptoms of acquired demyelinating polyneuropathy
large-fibre sensory dysfunction (buzzing and tingling sensation)
motor weakness
diminished reflexes
severe motor weakness with minimal atrophy
What is small fibre sensory neuropathy (SFSN)
Disorder in which only the small sensory cutaneous nerves are affected
symptoms of small fibre sensory neuropathy (SFSN)
- unusual sensations such as pins-and-needles
- pricks
- tingling
- numbness
- burning pain or coldness and electric shock-like brief painful sensations
- start in the feet and progress upwards
What sort of damage can nerve cells go through?
compressed
sheath loss
disconnection
degeneration
what is Guillan-barre syndrome (GBS)
Acute paralytic polyneuropathy that affects the peripheral nervous system
What’s the feature of Guillan-Barre syndrome?
- symmetrical ascending weakness
- peripheral loss of sensation
- neuropathic pain
- Absence reflexes
- absent/depressed tendon reflexes
- facial nerve weakness
- double vision
- difficult speaking
- constipation
- urinary incontinence
- orthostatic hypotension
How often does it take GBS symptoms to occur?
2-4weeks
What to investigate on GBS?
- nerve conduction test & electromyographic studies
- clinically
- lumbar puncture
- check pulmonary function
What tool is to use for diagnosing GBS?
Brighton criteria
management of GBS
- IV immunoglobulins
- Plasmapheresis
- supportive care
- VTE prophylaxis (low-molecular-weight heparin)
What is Myasthenia gravis
An Autoimmune condition affecting the neuromuscular junction.
It causes muscle weakness that progressively worsens with activity and improves with rest.
Clinical presentation of Myasthenia gravis
- muscle weakness
- worse with increased muscle use
- improve with rest
- affects proximal muscle and small of the head and neck
- Diplopia (double vision)
- ptosis
- difficulties swallowing
Diagnosis of Myasthenia gravis
Blood test to look for:
- ACH-receptor antibodies
- MUSK antibodies
- serial pulmonary function tests
–> CT/MRI scan
–> edrophonium test
What is the treatment of myasthenia gravis?
- Pyridostigmine & neostigmine (acetylcholinesterase inhibitors)
- steroids & azathioprine (immunosuppression)
- thymectomy
- Rituximab
- Eculizumab
(monoclonal antibodies)
What is the treatment for a myasthenic crisis?
- Intubation and mechanical ventilation
- plasma exchange / intravenous immunoglobulin
- supportive care
- corticosteroid
What is Charcot-Marie-Tooth Disease?
progressive hereditary disorders of the peripheral nervous system. It’s inherited, worsens over time and affects sensory & motor nerve cells
Clinical features of Charcot-Marie-Tooth disease
- loss of sensation on the feet, ankles and legs
- curled toes (hammer toes) and foot deformities
- difficulties of using hands
What is the investigation of Charcot Marie tooth disease?
- nerve conduction studies (NCS)
- genetic testing
- Hip X-ray
First-line treatment of Charcot-Marie-Tooth disease
- physiotherapy
What is Carpal tunnel syndrome?
Carpal tunnel syndrome (CTS) is a collection of symptoms and signs caused by compression of the median nerve in the carpal tunnel.
Risk factor of Carpal tunnel syndrome
Age between 40-60
Female
High BMI
Pregnancy
Diabetes
Clinical features of Carpal tunnel syndrome
- worse at night
- paresthesia
- numbness in the median nerve distribution
- muscle weakness
clumsiness with holding small objects / turning doorknobs
Diagnosis and investigation on carpal tunnel syndrome
electromyogram (EMG)
ultrasound of the wrist
MRI on the wrist
First-line treatment of carpal tunnel syndrome?
Wrist splint
