Occupational peripheral nerve damage

From WikiLectures

Toxic damage[edit | edit source]

  • Toxic neuropathy
  • Typical character – symmetric, sensorimotor, distal polyneuropathy
  • Sensory fibers are affected first because their bodies are in the dorsal root ganglion (i.e. outside the blood-brain barrier).
  • It is distal because the part of the neuron that is furthest from the center of regeneration (i.e. from the cell body) suffers the most
  • The longer the axon, the more susceptible it is to damage

Symptoms[edit | edit source]

  • Sensory - Paresthesia or tingling especially at night. Reduction or disappearance of reflexes - distal ones disappear first (e.g. Achilles tendon reflex)
  • Motor disorders appear later – typically there is Peroneal paresis (patient can't extend (lift) toes)

Examination[edit | edit source]

Toxicity[edit | edit source]

  • Lead, Mercury
  • Organic solvents – carbon disulfide, hexane, trichloroethylene, acrylamide, polychlorinated biphenyl

Dif. dg[edit | edit source]

Symptoms are nonspecific:[edit | edit source]

  • Mainly – alcoholic polyneuropathy (we will examine GGT (gamma-glutamyl transferase), CDT (carbohydrate-deficient transferrin))
  • Diabetic, Paraneoplastic (mainly lung, ovarian, or hematogenous)
  • Both in DM and in tumours, polyneuropathy can be the first symptom (must be considered when polyneuropathy occurs)

Therapy[edit | edit source]

  • Termination of toxic exposure, vitamins B1, B6, B12, E, vasoactive substances, nootropics, pain medications – anti-epileptics

Overuse damage[edit | edit source]

  • Tunnel syndromes
  • 80% of patients have carpal tunnel syndrome. Cubital tunnel syndrome is the second-most common

Other rare damages:

  • Peroneal nerve – compression when passing behind the head of the fibula (e.g. while squatting or kneeling)
  • Tibial nerve – pressure in the tarsal tunnel (when passing behind the inner ankle)
  • With frequent tiptoeing (plantar flexion) – Ballerinas (damage to the nerve by stretching), Jockeys (tightening in the stirrups), house painters (on stepladders)

Carpal tunnel syndrome[edit | edit source]

  • There will be some expansion of the carpal tunnel – it has two main etiologies
    • Endogenous - hormonal changes (the syndrome will manifest itself bilaterally), inflammation (tendovaginitis), and metabolic changes
    • Exogenous – post-traumatic, from manual work
  • The most common groups of activities leading to the syndrome:
    • Heavy physical work: flexor contractions (hammer, heavy loads)
    • Stereotypic repetition of finger flexion and extension (previously in milking cows, musicians, or typing)
    • Fine work with constant pinching of the fingers (watchmakers, fine mechanics)
    • Direct pressure on the wrist (dentists, scissor work, etc.)
  • Subjective symptoms:
    • First phase – morning numbness in the fingers
    • Second phase - nocturnal paresthesia
    • Third phase – daytime paresthesia (mainly when working with hands above the head (for example, holding on to a handrail in public transport))
    • Fourth stage – clumsiness of small movements
  • Objective signs – sensitivity disorders – we assess them on the 2nd finger (we compare sensation on the belly of the 2nd and 5th finger - the palmar part of the fifth finger is innervated by the ulnar nerve)
  • As stated, motor defects arise later – mainly abductor pollicis brevis muscle atrophy
    • The resulting atrophy of this muscle makes such a dimple laterally on the thenar eminence
  • We demonstrate the sign of a candle - hand palm-side up with the thumb sticking up, we push it into the palm and watch its resistance
  • Sensation on the thenar eminence is normal (the subcutaneous branch originates from the median nerve before entering the carpal tunnel)
  • Pseudoneuroma of the median nerve is formed - a spindle-like thickening of the nerve - as axoplasm (cytoplasm of axon) accumulates there due to the oppression
  • Provocation tests – Tinel's sign – perpendicular tapping of the retinaculum with fingers (direct percussion) causes paresthesias (burning or prickling sensation)
    • Wrist hyeprflexion will do the same
  • Objective examination - ENG (electroneurography) - the conduction speed of the axon on the forearm (before) and palm (after) will be normal, there is a slowdown in the tunnel

Dif. dg[edit | edit source]

  • Pronator teres syndrome (median compression more proximally on the forearm)
  • C6 root syndrome
  • Cervicobrachial syndrome

Therapy[edit | edit source]

  • Termination of exposure, splint positioning, vasoactive substances, NSAIDs, local corticoids
  • Invasive (last) option - surgery - usually the worker can no longer return to work, as the movement of the wrist is altered

Other Syndromes[edit | edit source]

  • Paresis of the ulnar nerve in the Ulnar nerve sulcus with claw hand deformity

Links[edit | edit source]

Related articles[edit | edit source]

Source[edit | edit source]

References[edit | edit source]

  • PELCLOVA, Daniela. Occupational diseases and intoxication. 2nd edition. Prague: Karolinum, 2006. 207 pp.  ISBN 80-246-1183-X .