Peripheral Neuropathies Flashcards
Carpal tunnel syndrome examination
Sensation in index>little finger, impairment on one side of ring finger
Weakness of thumb abduction and wasting of APB
Tinel and phalen signs
Carpal tunnel syndrome history
Pins and needles in fingers
Sensory loss or pain proximally or wrist
Weakness in thumb/fingers
Occurs for a few minutes at night on waking or when gripping
Tinel sign
A test for irritated nerves used to diagnose carpal tunnel
Taping on the nerve elicit a ‘pins and needles’ sensation over the distribution of the nerve
Phalen manoeuvre
A way to test for carpal tunnel by holding the hands at full forced flexion for 30-60 seconds, or at full extension for 2mins (reverse phalen)
The pressure in the carpal tunnel is raised by the contraction of FDP pulling the lumbricals into it,worsening any symptoms.
Pathology of carpal tunnel
Pressure on the nerve> demyelination> slow conduction
If pressure is prolonged > axonal loss > wasting of muscle
Demyelination is reversible, axonal loss much less
In CTS the median nerve conduction is slower than the ulna nerve
Carpal tunnel syndrome treatment
Early treatment is occupational
After this splinting
Steroid injections
Surgery
Ulnar neuropathy at the elbow
Often history of arthritis or trauma with a palpable ulnar nerve
Pain/tenderness at elbow and sensory loss in the lateral ring and little finger
Weakness and wasting in the small muscles of the hand
Common perineal nerve palsy
Foot drop or weakness and numbness
Made worse by compression (bending, squatting, crossing legs)
Often occurs after long periods of compression (flights) and usually recover after a couple of two days
Generalised peripheral neuropathies
Can be hereditary or acquired
Axonal or demyelination
Polyneuropathy (single continuous problem) or mononeuritis multiplex (multiple distinct mononeuropathy)
Length dependant polyneuropathy
Length dependant, glove and stockings distribution
Symmetrical, distal sensory loss/wasting/areflexia
Check for metabolic cause (glucose, B12, folate, thyroid)
Treat underlying cause and give drugs for pain (gabapentin, pregabalin, amotriptyline)
Pathogensis of peripheral neuropathies
Axonal –> muscle wasting, pain, sensory symptoms and signs but only ankle reflexes lost
Demyelinating –> weakness without wasting, motor signs, general loss of reflexes
Nerve conduction changes in peripheral neuropathies
Axonal –> small amplitude, Normal velocity/F waves
Needle EMG: denervation
Demyelination –> prolonged distal latency, slow velocity with conduction block, prolonged F waves
Needle EMG: possibly normal
F waves
When a nerve is stimulated in an EMG the impulse travels up the nerve to the spine and come back down producing a second wave
Diabetic neuropathies
Symmetrical distal length dependant sensory deficits
Proximal neuropathy lumbosacral radiculo-plexus neuropathy
Can also get mononeuropathy
Demyelination neuropathies
Hereditary–> Charcot-Marie-tooth disease
Acquired–> acute : Guillain-Barré syndrome
Chronic –> chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
IgM paraprotein-associated
Clinical findings in Guillain-Barré syndrome
Raised CSF protein but normal cells
Reduced conduction velocity/block due to patchy demyelinating neuropathy
Can lead to secondary axonal loss
Guillain-Barré syndrome
Acute ascending progressive paralysis, sensory loss and areflexia, often secondary to infection
Worsening progress over 1-3 weeks –> risk of respiratory muscle involvement or cardiac arrhythmias
Recover in 2-6 months
Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
Chronic form of GBS giving a syndrome similar to peripheral MS, with weakness more Than sensory loss
Usually worst proximal
Areflexia
Raised CSF protein
Causes of mononeuritis multiplex
Diabetes
Vasculitis, ANCA associated or secondary rheumatological or due to hepatitis B/C
Multiple nerve compressions
Bell’s palsy
Acute unilateral facial nerve weakness
May have pain behind the ear, Loss of taste or hyperacusis
UMN palsy effects all muscles equally, LMN palsy spares forehead
Treat with 10day prednisolone –> 75% improve spontaneuously
25% develop synkinesis/crocodile tears
Crocodile tears
A rare consequence of recovery from Bell’s palsy causes faulty regeneration of the nerve such that the patient sheds tears when the eat
Motor Neuron Disease - symptoms
MND refers to a collection of 5 syndromes with different presentations and symptoms
MND - treatment
No curative treatment but Riluzole (blocks TTX sensitive Na channels which occur in damaged neurons) prolongs survival for 2-3 months
MND classification
Amyotrophic lateral sclerosis (ALS) Primary Lateral sclerosis (PLS) Progressive muscular Atrophy (PMA) Progressive bulbar palsy (PBP) Pseudobulbar palsy
Amyotrophic lateral sclerosis (ALS)
Most common form of MND
a mix of UMN and LMN signs. 75% present with limb symptoms, 25% with bulbar symptoms
No sensory deficit
5% frontotemporal dementia and 30-50% show some subtle cognitive decline.
Primary Lateral sclerosis (PLS)
A rare form of MND with only UMN symptoms with onset after 50. commonly progressive leg spasticity with pain, but may start in hands or face –> slowly progressive with normal life span unless it progresses to ALS
Progressive Muscular atrophy (PMA)
A rare (4%) form of MND only affecting the LMNs with a life expectancy of ~ five years (ALS is less)
presents with atrophy, fasciculations and weakness
may present in just arms or legs, which has a better prognosis
Progressive Bulbar Palsy
25% of people diagnosed, affects CN IX,X,XII (LMN)
slow onset at 50-70yrs with 1-3 year prognosis
25% of PBP pts will go on to develop ALS
can show emotional changes if corticobulbar tract is involved
Pseudobulbar palsy
UMN damage in the bulbar region/corticobulbar tract of the brainstem. Presents with dysphagia, dysarthria, brisk jaw jerk, spastic tongue and labile affect.often found to have UMN signs in the limbs as well. Can be due to several reason and a form of MND
Cauda Equina syndrome
Compression or injury to the cauda equina at the end of the spinal cord (L1/2). Presents with low back pain +-radiation to the legs, LMN signs in the legs, saddle sensory abnormalities and sphincter dysfunction
