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RNS
- 3. Howard in Stålberg 2003 The neuromuscular junction
- 5. ChAT AP Multiple targets at the NMJ VGCC Choline VGKC AChR AChE Rapsyn MUSK AChEsterase NaC
- 6. Engel et al 2003
- 7. ACh synthesis and storage
- 9. End-plate activity - monophasic 10ms/div 50uV/div
- 10. Myasthenic disorders u Non-familial u Autoimmun MG (post) u LEMS (pre) u Toxins, drugs (pre or post) u Congenital syndromes u presynaptic, synaptic, postsynaptic Stålberg
- 11. Myasthenia Gravis Autoimmun disorder Other autoimmune disorders in MG Incidence 1/100.000 per year Female : male 3 : 2 Stålberg
- 12. Myasthenic disorders Myasthenia gravis reduced AChR antibodies to AChR (85%) Seroneg MG normal ACHR density anti-MUSK antibodies in 2/3 LEMS reduced release of Ach antibodies to presynaptic Ca-channels autonomic symptoms malignancy in 65% Stålberg
- 13. Stålberg
- 14. Stålberg
- 15. Tests for MG CLINICAL History Tests fatigue, Tensilon, ice test EMG Rep nerve slow-fast, postactivation stimulation facilitation/exhaustion Needle-EMG shape variability SFEMG jitter INTRACELL REC STAPEDIUS REFLEX OCULOGRAPHY TONOMETRY ACHR ANTIBODIES Stålberg
- 16. P.Activ. Facilitation (of Ach ejection) P.Activ. Exhaustion (of available Ach) Faradic or voluntary excertion decrease increase NM block
- 17. Schematic intracellular recordings, showing end-plate potentials - action potentials are not shown AP EPPs AP EPPs AP Normal MG -90 mV -60 mV Stålberg
- 18. Intracellular recordings, schematic with APs AP AP AP Normal MG -90 mV -60 mV Stålberg No AP from this jitter
- 19. Schematic explanation to the myasthenic decrement All or none reponse of individual motor end-plates CMAP representing the sum of above Stålberg
- 20. myasthenic fatigue Protocols in MG Stålberg et al, Clinical Neurophysiology Volume 130, Issue 9, September 2019, Pages 1688-1729
- 22. Protocol after rest and after 10 sec of activation 3 Hz, 10 stimuli immobilize the muscle max stim strength, 125% test at: rest after 10 sec of activation Stålberg
- 23. 3 Hz, 10 stimuli immobilize the muscle max stim strength, 125% test at: rest after 10 sec of act and after 1 minute Stålberg Immobilize the muscle Because shortening of the muscle will increase the CMAP ampl Max stim Always important for CMAP rec, but particularly here since small movements may cause insufficient stim Post exercise amplitude Gives info about number of excitable end-plates Why 3 HZ? 1HZ does not give decrement 10Hz gives facilitation and will mask a decrement 10stimuli We want to see the typical sadle shape contour, not present in other conditions with decrement Protocol after rest and after 10 sec of activation
- 24. 3 Hz, 10 stimuli immobilize the muscle max stim strength, 125% test at: rest after 10 sec of act and after 1 minute Stålberg Max stim Always important for CMAP rec, but particularly here since small movements may cause insufficient stim Post exercise amplitude Gives info about number of excitable end-plates Immobilize the muscle Because shortening of the muscle will increase the CMAP ampl Protocol after rest and after 10 sec of activation
- 25. 3 Hz, 10 stimuli immobilize the muscle max stim strength, 125% test at: rest after 10 sec of act and after 1 minute Stålberg Post exercise amplitude Gives info about number of excitable end-plates Post exercise decrement Reflects safety factor, reserve of Acetylcholine Max stim Always important for CMAP rec, but particularly here since small movements may cause insufficient stim Protocol after rest and after 10 sec of activation
- 26. 3 Hz, 10 stimuli immobilize the muscle max stim strength, 125% test at: rest after 10 sec of activation Stålberg Gives the physiological events: • Start condition • Post-exercise facilitation; amount of excitable end- plates and LEM Protocol after rest and after 10 sec of activation
- 27. Hatanaka, Oh, 2008 M&N Incremental response for different exercise duration in LEM
- 28. 3 Hz, 10 stimuli 60 sec of strong vol activation or after 1 sec 20 HZ stim. Test before, and after 5 sec, 1 min, 3 min directly after Stålberg Gives the physiological events: • Post-exercise exhaustion, which is related to the myasthenic fatigue Protocol after 60 sec of activation
- 29. Parameters to analyse initial amplitude decrement and amplitude at intervals after activity (postactivation facilitation and exhaustion) Stålberg
- 30. Repetitive Nerve Stimulation What do the parameters tell? Initial amplitude number of responding motor end-plates Decrement safety factor Facilitation condition of receptor population- - prognosis for treatment Exhaustion myasthenic fatigue Combined features special type of defect Stålberg
- 31. Rep.nerve stimulation: considerations • distal/proximal muscle • rest/fatigue • on/off treatment • cold/warm • stim. frequency • muscle fixation Stålberg
- 32. Muscles to test Generalized MG Deltoideus Trapezius Anconeus Nasalis Bulbar MG Nasalis Anconeus Trapezius Ocular MG RNS is quite insensitive Nasalis Start with SFEMG jitter
- 33. Schematic. Temperatur effect on EEP in normal and MG EPPs MG AP EPPs Normal -90 mV -60 mV Stålberg EPPs MG- cooling EPPs MG – warming (34o C) Normal-cooling -90 mV -60 mV Normal-warming -90 mV -60 mV
- 34. Fixation • Deltoideus • Trapezius • Anconeus • Nasalis • Orbicularis oculi • Rectus femoris • EDB • ADM Stålberg Fixation press elbow hold chair seat no no no no no strap around fingers
- 35. 5 ms 5 mV E Deltoid Stålberg 40 Shape of CMAP varies among muscles
- 37. Stålberg 43
- 38. Repetitive nerve stimulation Anconeus muscle after rest 0 sec after 20 s activation 1,5 min after activation 3 Hz -2% -6% 3 Hz -2% -2% 3 Hz -4% -7% Stålberg
- 39. Repetitive nerve stimulation in a patient with severe MG Rest, 3 Hz 10 stim Directly after 20 s act. Post-act facilitation 0 sec after 20 s activation 1min after activation 3 Hz -76% -80% 3 Hz -18% -26% 3 Hz -75% -78% after rest Left ADM Stålberg
- 40. Congenital myasthenia (slow channel) Repetitive nerve stimulation Stålberg 0 sec after 20 s activation 1min after activation 3 min after activation 3 Hz -79% -78% 3 Hz -67% -60% 3 Hz -80% -62% 10 Hz -79% -39% after rest
- 41. Right ADM Stålberg Rest, 3 Hz 10 stim Directly after 20 s activation = facilitation 3 Hz -26% -31% 3 Hz -6% -8% 20 Hz 30 % 35% 50 Hz >500% >500% LEM, at rest and after activation
- 42. Decrement; 5% confidence limits Muscle n decrement ADM 66 -3,4 Anconeus 255 -3,8 Deltoid 92 -4,8 Nasalis 239 -4,9 Trapezius 208 -4,0 Stålberg 2014 Stålberg 49
- 43. Decrement in 2 proximal muscles Mean decrement 24.8 15.8 Mean amplitude 8.0 6.4 Stålberg
- 44. Decrement at rest -20 -10 0 10 20 30 40 50 60 70 (%) M. abd dig min M. deltoideus M. anconeus Stålberg
- 45. Decrement at rest M. abd dig min M. deltoideus M. anconeus Stålberg
- 46. Decrement at rest Delt vs Trap
- 47. -50 -40 -30 -20 -10 0 10 Decrement at rest Delt vs Anconeus
- 48. Decrement at rest Trap vs Anconeus
- 49. Is there? myasthenia good/ bad effect of AchE inhib´s cholinergic overdose LEM McArdle, myotonia Stålberg
- 50. Facilitation after exercise Tim and Sanders, M&N, 1994
- 51. Facilitation with 20 Hz stimulation in LEM Tim and Sanders, M&N, 1994
- 52. Congenital myasthenia (slow channel) Abnormal CMAP Stålberg
- 53. 5-year old girl with rapsyn deficiency
- 54. 5-year old girl with rapsyn deficiency Thenar muscles15 Hz stim for 5 minutes
- 55. 5-year old girl with rapsyn deficiency RNS with 3 Hz stim following prolonged activation 15 Hz 5 min
- 56. Activity between CMAP and F-response -variable shape •Extradischarges –Acetylcholine induced –Channelopathies •Myotonia (PEMD) –Motor neuron pathology •Fasciculations •Other spont activity
- 57. Extradischarges in Mestinon overdose Some special features Irregular low ampl, or regular slow after-waves Disappear with stim frequency > 2Hz May be repetitive discharges
- 58. 5 ms 5 mV A 1 mV 10 ms B Ulnar nerve Peroneal nerve Cholinergic extradischarges (MUSK +) pronounced (A), slight (B)
- 59. wrong muscle cold muscle stim and recording positions incorrect subliminal stimulation movements during RNS changed position after vol activation poor signal quality erroneous interpretation Pitfalls