Disorders of the PNS Flashcards
What is a nerve issue arising at the nerve root known as?
Radiculopathy/Ganglionopathy
What is a nerve issue arising at a nerve plexus known as?
Plexopathy
What are some forms of peripheral neuropathy?
Mononeuropathy - 1 nerve affected
Mononeuritis multiplex
Peripheral neuropathy (length dependant)
Where is the most common entrapment site of the median nerve?
Carpal tunnel (Wrist)
Where is the most common entrapment site of the ulnar nerve?
Cubital tunnel (Elbow)
Where is the most common entrapment site of the radial nerve?
Spiral groove of humerus
Where is the most common entrapment site of the posterior interosseous nerve?
Supinator muscle (Forearm)
Where is the most common entrapment site of the lateral cutaneous nerve of thigh?
Inguinal ligament
Where is the most common entrapment site of the common perineal nerve?
Neck of fibula
Where is the most common entrapment site of the posterior tibial nerve?
Tarsal tunnel (Flexor retinaculum - foot)
What is foot drop a sign of?
Disease or trauma affecting the common peroneal nerve
What is mono neuritis multiplex?
A condition in which there is damage to 2 or more distinct nerve areas
What peripheral nerve condition is shown?
Mononeuritis multiplex
What are some conditions that can cause mononeuritis multiplex?
- Diabetes mellitus
- Leprosy
- Vasculitis, including eosinophilic granulomatosis with polyangiitis amyloidosis (most common cause)
- Malignancy
- Neurofibromatosis
- HIV and hepatitis C infection
- Multifocal motor neuropathy with conduction block
What are some forms of polyneuropathy?
Hereditary sensory motor neuropathy
Guillain-Barré syndrome
Idiopathic
Metabolic
Toxic
Autonomic
What is the old name for hereditary sensory motor neuropathy?
Charcot-Marie-Tooth disease
What is HSMN?
Inherited disease that affects the peripheral motor and sensory nerves
Describe the genetics of HSMN?
AD, AR, X-linked - hundreds of mutations, demyelinating and axonal varieties
What is the common sub-type of HSMN?
HSMN Ia is the most common type (70%) - autosomal dominant demyelinating neuropathy
What are some symptoms of HSMN?
Typical presenting symptom is weakness of the feet and ankle
What are some signs of HSMN?
Absent tendon reflexes
Foot and ankle weakness
Bilateral foot drop
Muscle atrophy below knee (Stork leg)
Pes cavus
Hand muscle atrophy
What are some investigations required in HSMN?
- Tests to exclude other causes of neuropathy e.g. bloods, serum and urine protein electrophoresis, muscle biopsy, CSF
- Genetic studies
- Nerve conduction studies
How is HSMN managed?
No management
Just support from MDT members
What is Guillain-Barré syndrome?
An ‘acute paralytic polyneuropathy’ that affects the peripheral nervous system
What are some bugs that can cause Guillain-Barré syndrome?
Campylobacter jejuni
Cytomegalovirus
Epstein-Barr virus
Describe the pathophysiology of Guillain-Barré syndrome?
Infection leads to molecular mimicry:
B-cells create antibodies against the pathogenic antigens, which also match those on the nerve cells, therefore targeting proteins on the myelin sheath or the axon
How does Guillain-Barré syndrome present?
- 4 weeks post-infection
- Symmetrical ascending weakness
- Reduced reflexes
- Peripheral loss of sensation
- Neuropathic pain
- Possible cranial nerve weakness
How is Guillain-Barré syndrome diagnosed?
Clinical diagnosis
- Nerve conduction studies
- Lumbar puncture (Raised protein)
How may patients with respiratory failure be managed in Guillain-Barré syndrome?
Intubation
Ventilation
Admission to the ICU
What vitamin deficiencies can cause metabolic neuropathy?
B12
Folate
Thiamine (B1)
How is Guillain-Barré syndrome managed?
- IV Ig (1st) or plasma exchange (2nd)
- Supportive care
- VTE prophylaxis
What are some causes of toxic neuropathy?
Alcohol
Amiodarone
Phenytoin
Chemotherapy (Cisplatin/Vincristine)
What are some possible causes of metabolic neuropathy?
- Diabetes
- Uraemia
- Hepatic and thyroid disease
- Acute intermittent porphyria
- Amyloidosis
- Vitamin deficiency
What is Wernicke-Korsakoff’s syndrome?
Thiamine-responsive encephalopathy due to damage in the brainstem and its connections
Usually caused by alcoholism
When may neuropathy be seen in cancer?
Polyneuropathy as a paraneoplastic syndrome
Myeloma
Plasma cell dyscrias
What are some systemic diseases that may cause vasculitic neuropathy?
SLE
Polyarteritis nodosa
Granulomatosis with eosinophilia
Rheumatoid disease
What are some symptoms of autonomic neuropathy?
Postural hypotension
Urinary retention
Erectile dysfunction
Nocturnal diarrhoea
Diminished sweating
Impaired pupillary responses
Cardiac arrhythmias
What are some causes of chronic autonomic neuropathy?
Diabetes
Amyloidosis
Hereditary
What are some causes of acute autonomic neuropathy?
Corticobulbar syndrome
Porphyria
How are peripheral neuropathies managed?
- Treat cause
- Symptomatic treatment
What are some symptomatic treatments of peripheral neuropathy?
Physiotherapy
Orthotics
Neuropathic pain relief
How is vasculitis neuropathy managed?
Pulsed IV methylprednisolone + Cyclophosphamide
