Peripheral Neuropathies: Length Dependent, Entrapment, Radiculopathy, Cord, Inherited, Systemic Flashcards
Length dependent neuropathies
- presentation
- most common cause
- management
MOST COMMON POLYNEUROPATHY
Start distally, symmetrical => progress upwards
-SENSORY LOSS (ST & D) > motor loss
-LMN signs - more likely in inflammatory causes
Most common - diabetic neuropathy (gradual progression)
Inflammatory AI causes - subacute progression
Manage underlying cause
Entrapment neuropathies
- presentation, pathophysiology
- management
Compression of nerve => gradual pain, tingling, sensory, motor loss
Conservative - postural advice, splinting
Medical - local steroid injections, surgical decompression
Carpal Tunnel Syndrome
- risk factors
- presentation
- investigations
Median - C6-T1 Myxedema Edema Diabetes Idiopathic Acromegaly Neoplasm (ganglion, lipoma) Trauma Rheumatoid arthritis Amyloidosis Pregnancy
Relieved by movement
Worsened at night, compression of tunnel
Thenar wasting and LOAF weakness
Tinel, Phalen
Ulnar nerve neuropathy
- presentation, pathophysiology
- how would you localise the lesion?
Ulnar - C8-T1
Compression at medial epicondyle => medial hand symptoms, esp in tips
If symptoms also in median distribution => C8 radiculopathy, plexopathy?
Lesion at wrist - ulnar intrinsic muscles, finger tips
Lesion at elbow - +forearm ulnars, hand cutaneous
C8/T1 radiculopathy, plexopathy - +median involvement
Causes
- trauma, arthritis
- idiopathic - external pressure, occupational
- neoplastic
- diabetes
Foot drop
- pathophysiology
- presentation
- cause and risk factors
Weak dorsiflexion
Most commonly due to
-compressed common peroneal at fibular head, sciatic nerve (knee flexion affected)
-L5 radiculopathy - SLR
Variable sensory loss - dorsum, lateral leg
Pressure on nerve
- positional - legs crossed, anaesthesia position, strawberry pickers knee
- weight loss
- trauma - fracture
Radiculopathy
- pathophysiology
- common locations, presentation
- diagnosis
- management
Compression of nerve root => dermatomal pain
Brachialgia (C6-7) - back of arm, thumb-middle finger
Lumbosacral - MOST COMMON (SLR)
- sciatica (L4-S3) - shooting pain down leg
- L4-5 - toe extension
- L5-S1 - ankle jerk reduced, weak plantar flexion
Precipitating event => acute pain, weakness, dermatomal loss
Clinical diagnosis but MRI for atypical/persistent
1st line - physio, rest, analgesia (6wks)
Surgical decompression if no resolution, progression
Inherited neuropathy
- presentation
- most common
- investigations
Length dependent - often occur in feet, skeletal deforminities
Familial
Charcot Marie Tooth
- pedigree analysis, genetic tests => specialist referral
- neuropathy bloods
Systemic multiple mononeuropathies
- pathophysiology
- possible cause, presentation
- management
Vasculitis affects blood supply of nerves => polyneuropathy
-important to treat ASAP as nerves generally do not recover
Vasculitis
Systemically unwell
Many nerves affected
Churg Strauss
-ANCA vasculitis => pain and systemic symptoms
Underlying cause
-IS => cyclophosphamide
Useful investigations to assess neuropathy and why
-blood tests
FBC - VitB12 deficiency - length dependent
U&E, urine dipstick, HbA1c, Ca - kidney function, diabetes
TFT, TSH - hyperthyroid (increased metabolic stress on nerves), hypothyroid (fluid retention compressing nerves)
LFT - ALD?
ESR, CRP - inflammatory causes?
ANA, ANCA - vasculitic neuropathies (Churg Strauss, SLE)
Paraneoplastic antineuronal, ganglioside AB - underlying tumour, GBS
Treponemal - neurosyphillis (tabes dorsalis, sensory ataxia)
HIV - neuropathic pain from opportunistic neuropathies/inflammatory stress from high viral load/side effect of meds
Neurotip test - ST, dorsal column sensory
Nerve conduction test - nerve/myelin damage
Rare -nerve biopsy, microneurography
Severity of nerve injuries
Non degenerative
Neuropraxia - myelin divided
-recovery takes 4-6wks
Degenerative => Wallerian degeneration distal to lesion => wasting
Axonotmesis - axon divided but connective tissue safe
-Recovery takes months
Neurotmesis - axon and connective tissue divided
-No spontaneous recovery
Cauda equina syndrome
- pathophysiology, presentation
- management
SC ends at L1-2
Cauda equina - motor, sensory, parasympathetic of bladder
Leg weakness, saddle anaesthesia
Back pain
Urinary retention, sexual dysfunction
LMN, UMN signs
Urgent MRI => surgical decompression
Meralgia paraesthetica
- presentation, pathophysiology
- risk factors
- management
Compression of lateral cutaneous thigh nerve => pain, allodynia, numb
-metabolic stress + inflammation
Tight clothing, obesity/weight gain, diabetes (check HbA1c)
Weight loss, looser clothing
Guillain Barre
- progression of symptoms
- management
Most common acute NM weakness
-prodromal illness => backache, distal tingling => symmetrical weakness, areflexia, facial, resp, swallowing affected => peak at 4wks
1st line - IVIG + supportive
