Reactions have also been described as opisthotonos and dystonia, with no evidence of seizure activity (Table 2). These movements may be attributed to an imbalance of cholinergic-dopaminergic neurotransmitters in the basal ganglia because neuromuscular coordination involves a fine balance between dopamine receptors (inhibitory) and cholinergic receptors (excitatory) (39). Propofol is assumed to cause an imbalance of basal ganglia transmitters that produce an increase in excitatory cholinergic output.
The mechanisms underlying the effectiveness of benztropine are uncertain, particularly as cholinesterase inhibitors that increase nicotinic and muscarinic receptor activity are reported to antagonize the effects of propofol on consciousness (40). Benztropine is a tertiary amine with mixed anticholinergic, antihistaminic, and dopanergic properties (41). It may act by blocking intrastriatal cholinergic activity and thereby restoring central neurotransmitter balance. The recommended dose for treatment of drug-induced extrapyramidal side effects is 2 mg IV. This dose may be repeated every 30 minutes until symptoms resolve (41). Side effects are predictable because of drug actions (e.g., sedation, tachycardia, dry mouth).
We propose that the management of excitatory reactions to propofol depends on the appearance of the abnormal movements. For a dystonic reaction, benztropine 2 mg IV is recommended because a previous study reported that benztropine provided a shorter time to recovery with fewer side effects than diphenhydramine (39). Diphenhydramine has also been reported to induce acute dystonia (42). In contrast to dystonic reactions, the management of seizurelike reactions should be the same as for any generalized seizure, with the exception of the administration of propofol.
In summary, propofol-induced neurological reactions can be divided into dystonic and seizurelike. Benztropine may be used to treat dystonic reactions and also as a rapid diagnostic tool to avoid unnecessary and costly investigations of abnormal neuroexcitatory movements (39).
The authors thank Jenny Lam-McCulloch for her assistance with preparation of the manuscript.
1. Ries C, Scoates P, Puil E. Opisthotonos following propofol: a nonepileptic perspective and treatment strategy. Can J Anaesth 1994; 41: 414–19.
2. Ananthanarayan C. Dystonic reaction after anesthesia. Can J Anaesth 2001; 48: 101–3.
3. Islander G, Vinge E. Severe neuroexcitatory symptoms after anaesthesia: with focus on propofol anaesthesia. Acta Anaesthesiol Scand 2000; 44: 144–9.
4. Finley G, MacManus B, Sampson S, et al. Delayed seizures following sedation with propofol. Can J Anaesth 1993; 40: 863–5.
5. DeFriez C, Wong H. Seizures and opisthotonos after propofol anesthesia. Anesth Analg 1992; 75: 630–2.
6. Stoddart P, Gill R, Lim M. Hysteria: a cause for opisthotonus. Anaesthesia 1992; 47: 1014.
7. Gadalla F, Spencer J. Prolonged delirium after propofol. Can J Anaesth 1996; 43: 877–80.
8. Jones G, Boykett M, Klock M. Propofol, opisthotonus and epilepsy. Anaesthesia 1988; 43: 905.
9. Modica PA, Tempelhoff R, White PF. Pro- and anticonvulsant effects of anesthetics (Part I). Anesth Analg 1990; 70: 303–15.
10. Cameron A. Opisthotonos again. Anaesthesia 1987; 42: 1124.
11. Wittenstein U, Lyle D. Fits after alfentanil and propofol. Anaesthesia 1989; 44: 532–3.
12. Hendley B. Convulsions after cocaine and propofol. Anaesthesia 1990; 45: 788–9.
13. Shearer E. Convulsions and propofol. Anaesthesia 1990; 45: 255–6.
14. Thomas J, Boheimer N. An isolated grand mal seizure 5 days after propofol anaesthesia. Anaesthesia 1991; 46: 508.
15. Makela J, Iivanainen M, Pieninleroinen I, et al. Seizures associated with propofol anesthesia. Epilepsia 1993; 34: 832–5.
16. Sutherland M, Burt P. Propofol and seizures. Anaesth Intensive Care 1994; 22: 733–7.
17. Strachan A, Raithatha H. Propofol myoclonus. Can J Anaesth 1996; 43: 536–7.
18. Cochran D, Price W, Gwinnutt C. Unilateral convulsions after induction of anaesthesia with propofol. Br J Anaesth 1996; 76: 570–2.
19. Harrigan P, Browne S, Quail A. Multiple seizures following re-exposure to propofol. Anaesth Intensive Care 1996; 24: 261–4.
20. Eimerl D, Steiner I. Case 2: 1995—seizures associated with propofol anesthesia. Isr J Med Sci 1996; 32: 334–6.
21. Bendiksen A, Larsen L. Convulsions, ataxia and hallucinations following propofol. Acta Anaesthesiol Scand 1998; 42: 739–41.
22. Herrema I. A 10-second convulsion during propofol injection? Anaesthesia 1989; 44: 700.
23. McManus K. Convulsion after propofol/enflurane. Anaesth Intensive Care 1992; 20: 245.
24. Dingwall A. Oculogyric crisis after day case anaesthesia. Anaesthesia 1987; 42: 565.
25. Saunders P, Harris M. Opisthotonus and other unusual neurological sequelae after outpatient anaesthesia. Anaesthesia 1990; 45: 552–7.
26. McHugh P. Acute choreoathetoid reaction to propofol. Anaesthesia 1991; 46: 425.
27. Reynolds L, Koh J. Prolonged spontaneous movement following emergence from propofol/nitrous oxide anesthesia. Anesth Analg 1993; 76: 192–3.
28. Gildar J. Another case report of opisthotonos and propofol. Anesth Analg 1993; 76: 1171.
29. Orser B, Oxorn D. Propofol, seizure and antidepressants. Can J Anaesth 1994; 41: 262–7.
30. Hughes N, Lyons J. Prolonged myoclonus and meningism following propofol. Can J Anaesth 1995; 42: 744–6.
31. Zabani I, Vaghadia H. Refractory dystonia during propofol anaesthesia in a patient with torticollis-dystonia disorder. Can J Anaesth 1996; 43: 1062–4.
32. Bragonier R, Bartle D, Langton-Hewer S. Acute dystonia in a 14-yr old following propofol and fentanyl anaesthesia. Br J Anaesth 2000; 84: 828–9.
33. Strowbridge N. Postoperative opisthotonus following the use of propofol. J R Army Med Corps 1989; 135: 79–80.
34. deLima J, Scarf M, Cooper M. Propofol “convulsions” again? Anaesth Intensive Care 1992; 20: 396–7.
35. Diltoer M, Rosseneu S, Ramet J, et al. Anticholinergic treatment for choreoathetosis in a child after induction with propofol. Anesth Analg 1996; 82: 669–75.
36. Modica PA, Tempelhoff R, White PF. Pro- and anticonvulsant effects of anesthetics (Part II). Anesth Analg 1990; 70: 433–44.
37. Borgeat A, Wilder-Smith O, Tassonyi E, Suter P. Propofol and epilepsy: time to clarify. Anesth Analg 1994; 78: 190–9.
38. Orser B. Propofol-induced neuroexcitation and receptor desensitization. Can J Anaesth 1994; 41: 366–71.
39. Lee A. Treatment of drug-induced dystonic reactions. JACEP 1979; 8: 453–7.
40. Meuret P, Backman S, Bonhomme V, et al. Physostigmine reverses propofol-induced unconsciousness and attenuation of the auditory steady state response and bispectral index in human volunteers. Anesthesiology 2000; 93: 708–17.
41. Schatzberg A, Nemeroff C. Textbook of psychopharmacology. 2nd ed. Washington DC: American Psychiatric Press, Inc, 1998.
42. Etzel J. Diphenhydramine-induced acute dystonia. Pharmacotherapy 1994; 14: 492–6.