Peripheral Neuropathy Flashcards
What sensory modalities are carried in the “large fibres”?
Joint position and vibration sense
What sensory modalities are carried in the dorsal columns?
Proprioception and vibration, fine touch and 2-point discrimination
What sensory modalities are carried in the small fibres?
Pain and temperature (spinothalamic tracts)
Autonomic function
What sensory modalities are carried in the spinothalamic tracts?
Pain, temperature and crude touch
When diagnosing a peripheral neuropathy, what are important factors to consider?
- If it is sensorimotor, motor or sensory
- If sensory, if it is small or large fibre
- Is there any autonomic involvement? Features suggestive of autonomic dysfunction include resting tachycardia and postural BP drop
What skin changes may be associated with a peripheral neuropathy?
- Dry
- Thin
- Atrophic
- Hypopigmentation
- Loss of hair
- Callosities and ulcer formation (associated diseae)
- Signs of chronic infection
What are Charcot’s joints? (neuropathic joints)
Swollen, deformed joints with abnormal ROM.
Siggest loss of pain and proprioception
May have crepitus
Ankle and elbow joints most commonly affected, but may affect any joint
How would a motor neuropathy manifest?
LMN pattern with distal-to-proximal gradient (longest fibres affected first)
Affects upper limbs once disease reaches the knee
Where should you look for wasting in a motor neuropathy?
Upper limb- first dorsal interossei (between thumb and first finger).
Small muscles of hands with dorsal guttering and MCP hypertextension and IP joint flexion deformities
Lower limb- tibialis anterior
What pattern of sensory loss would you expect in a peripheral sensory neuropathy?
Glove and stocking distribution
Usually symmetrical ascending pattern of loss- upper limbs only usually affected once sensory loss reaches the knees.
May not affect all sensory modalities
What types of gait would be suggestive of a peripheral neuropathy?
High steppage gait
Wide based gait
What would a high steppage gait suggest?
Loss of proprioception at the ankle (sensory large fibre loss) and/or foot drop (motor neuropathy)
What type of peripheral neuropathy would be suggested by a wide-based gait?
Sensory- patients often watch the gound as the walk to use visual input to compensate for loss of proprioception
What test that can be carried out on examination would you expect to be positive in a patient with a sensory neuropathy?
Romberg’s- standing with feet together and shutting eyes –> unsteadiness
Stand close to the patient and support them!
What are the common causes of a sensorimotor neuropathy?
- Common:
- ETOH
- DM
- Drugs:
- Chemotherapeutic (vincristine, paclitaxel, cisplatin),
- Rheum drugs (gold, allopurinol
- Endocrine: Hypothyroidism
- Vascular: Vasculitis
- Acquired: CIDP/GBS
- Metabolic: Uraemia
- Neoplastic: Paraneoplastic syndrome
- Congenital:
- Hereditary motor and sensory neuropathies
