Neurological Occupational Diseases

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Neurological Occupational Diseases

  1. 1. Neurological Occupational Diseases Assoc. Prof. Pavel Urban, M.D. Ph.D.
  2. 2. Proportion of Neurological Occupational Diseases in the Total Number of Occupational Diseases 35 30 25 Peercent 20 15 10 5 0 1996 1997 1998 1999 2000 2001 2002 2003 2004 Year
  3. 3. Main Categories of Occupational Diseases in 2004 11% 2% 28% Neur ological Respir ator y 17% Der matoses Infections Intoxications Other s 21% 21%
  4. 4. Neurological Occupational Diseases in 2004 1% 4% 1% 10% Car pal tunnel sy Cubital tunnel sy Combinations Neur obor eliosis Tick-bor ne encephalitis 84%
  5. 5. Prerequisites for a Diagnosis of a Neurological Occupational Disease • Typical clinical manifestation • Reasonable exclusion of alternative causes • Proof of relevant exposure • Appropriate temporal association between exposure and disease
  6. 6. Neurological Occupational Diseases Caused by Chemical Noxae
  7. 7. (1) Toxic Encephalopathy
  8. 8. Clinical Manifestation of Toxic Encephalopathy • Pseudoneurasthenic syndrome • Psychoorganic syndrome • Dementia
  9. 9. Laboratory Tests for Toxic Encephalopathy • Psychological examination • Electroencephalography • Evoked potentials (P300, VEP, BAEP) • Neuroimaging methods (CT, NMR, PET, SPECT)
  10. 10. The Most Frequent Causes of Occupational Toxic Encephalopathy Organic solvents mixture Solvent syndrome Carbon disulphide Psychiatric disorders Toluene Euphoria, pseudohallucinations Mercury vapor Erethism Carbon monoxide Parkinsonian syndrome Manganese Parkinsonian syndrome
  11. 11. Differential Diagnosis of Toxic Encephalopathy • Non-toxic causes of diffuse encephalopathy – Aging – Incipient neurodegenerative disorder • Non-occupational neurotoxicants – Alcohol – Drug abuse
  12. 12. Treatment of Toxic Encephalopathy • Removal from exposure • Nootropic drugs – Piracetam – Gingko biloba preparations • Free radicals scavengers – Vitamin E
  13. 13. (2) Toxic Neuropathy
  14. 14. General Characteristics of Toxic Neuropathy • Symmetrical • Sensorimotor • Distal • Polyneuropathy
  15. 15. • Distal axonopathy – “dying back process“
  16. 16. Clinical Manifestation of Toxic Polyneuropathy • Sensory disturbances – Paresthesiae and numbness in a “gloves and stockings” distribution – Tactivle, thermal, and vibratory sensation diminished • Deep tendon reflexes diminished or absent • Motor disturbances – Usually mild – Initial sign: dorsiflexion of the big toe weakened
  17. 17. Laboratory Tests for Toxic Polyneuropathies • Nerve conduction studies (the sural and tibial nerves) • Electromyography • Quantitative sensory testing • Somatosensory evoked potentials (detection of toxic myelopathy)
  18. 18. • Central-peripheral distal axonopathy
  19. 19. Most Frequent Causes of Occupational Toxic Neuropathies Toxic metals Lead, Thalium, Mercury Organic solvents Carbon disulphide, Trichlorethylene, n-Hexane Others Acrylamide, TCDD, Organophosphates
  20. 20. Differential Diagnosis of Toxic Neuropathy • Alcoholic polyneuropathy – CDT – Carbohydrate Deficient Transferin • Diabetic polyneuropathy • Paraneoplastic polyneuropathy
  21. 21. Treatment of Toxic Polyneuropathy • Removal from exposure • Vasoactive drugs • Vitamins (B1, B6, B12, E) • Antiepileptic drugs – carbamazepin – gabapentin – pregabalin
  22. 22. Neurological Occupational Diseases Caused by Physical Factors
  23. 23. (1) Long-term overload of extremities by physical work (2) Working with vibrating tools
  24. 24. (1) Long-term overload of extremities by physical work (1) Heavy physical work (2) Highly repetitive movements
  25. 25. Occupation-Related Compressive Neuropathies
  26. 26. • Upper extremities – Median nerve • Pronator teres syndrome • Carpal tunnel syndrome – Ulnar nerve • Cubital tunnel syndrome • Canalis Guyoni syndrome – Radial nerve • Supinator syndrome • Lower extremities – Fibular nerve – Tibial nerve • Tarsal tunnel syndrome
  27. 27. Carpal Tunnel Syndrome
  28. 28. ahok Etiology of Carpal Tunel Syndrome • Endogenous factors – Inflammation • Tendinitis • Dermatomyositis – Endocrinological changes • Pregnancy • Birth control pills • Ovarial hypofunction • Hypothyroidism – Metabolic changes • Diabetes mellitus • Gout • Exogenous factors – Post-traumatic changes – Manual work
  29. 29. Types of Occupational Activities Related to CTS • Static overload due to forceful and repetitive contraction of flexor muscles in the forearm – Examples: working with a hammer or grinder, manipulating heavy loads • Stereotyped repetitive flexion-extension of fingers – Examples: manual cow-milking, typing, playing musical instruments • Activities involving pinching, screwing etc. – Examples: clockmakers, minute work • Direct pressure on the wrist – Examples: dentists, bikers, working with scissors
  30. 30. Subjective Symptoms of CTS • Numbness upon awaking • Nocturnal paresthesiae (“Brachialgia paresthetica nocturna”) • Daily paresthesiae • Clumsy hand movements
  31. 31. Objective Signs of CTS • Hypesthesia in the distal median area • Weakness of the abductor pollicis brevis muscle • Muscle and skin trophic changes • Local findings – Punctum dolorosum – Pseudoneuroma • Provocative tests – Tinel’s sign – Phalen’s sign (Flexion test) – Extension test – Elevation test – Digital compression test
  32. 32. Laboratory Diagnostic Tests for CTS • X-ray examination • CT, NMR • Quantitative sensory testing • Nerve conduction studies • Needle electromyography
  33. 33. Differential Diagnosis of CTS • Proximal median neuropathy (pronator teres syndrome) • Brachial plexopathy (upper trunk) • Thoracic outlet syndrome • Cervical radiculopathy (especially C6) • Polyneuropathy
  34. 34. Treatment of CTS • Removal from exposure • Splinting of the wrist • Vasoactive drugs • Nonsteroidal anti-inflammatory drugs • Local application of corticosteroids • Surgery
  35. 35. Occupational Compressive Neuropathies in the Lower Extremities • Compression of the Fibular nerve – Examples: potato-lifters, miners, pavers, carpetlayers • Tarsal tunnel syndrome (Tibial nerve) – Examples: ballet dancers, jockeys, long- distance runners
  36. 36. PNS Damage Caused by Working with Vibrating Tools • Mononeural lesion – Pathophysiological mechanism: compressive neuropathy – Most frequently - CTS • Bineural lesion – Pathophysiological mechanism: ischemic neuropathy – Both the median and ulnar nerves damaged – Frequent association with vibration white fingers
  37. 37. Occupational Cramps • Synonyms – Occupational spasms – Occupational neuroses • Examples – Graphospasm – Telegraphist’s cramp – Trumpeter’s mouth – Horn player’s torticollis • Pathopysiology – Focal dystonia? – Psychogenic origin? • Treatment – Behavioral techniques – Botulinum toxin injections

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