Dystrophin deficiency, inhalational anesthetics, and rhabdomyolysis

[Trigger-free anesthesia : Indications and safe application]

The safe anesthesiological care of patients with neuromuscular diseases poses a particular challenge for anesthetists. Only a small group of muscle diseases and syndromes are associated with an increased risk of malignant hyperthermia and therefore require trigger-free anesthetic procedures avoiding volatile anesthetics and succinylcholine. These diseases are frequently associated with mutations in the RYR1, CACNA1S or STAC-3 genes. In other neuromuscular diseases, anesthetic-induced rhabdomyolysis can occur. Therefore, volatile anesthetics should be avoided in these patients in addition to the contraindication for succinylcholine. In other neuromuscular diseases the risk of a propofol infusion syndrome or myotonic crises can be elevated or the duration of the effect of non-depolarizing muscle relaxants can be changed in an incalculable way. In every case an individual anesthetic aproach including the avoidance of potential pharmacological or non-pharmacological triggers is essential for the safety of the patients.

Anaesthesia and neuromuscular disorders: what a neurologist needs to know

Neurologists are often asked for specific advice regarding patients with neuromuscular disease who require general anaesthesia. However, guidelines on specific neuromuscular disorders do not usually include specific guidelines or pragmatic advice regarding (regional and/or general) anaesthesia or procedural sedation. Furthermore, the medical literature on this subject is mostly limited to publications in anaesthesiology journals. We therefore summarise general recommendations and specific advice for anaesthesia in different neuromuscular disorders to provide a comprehensive and accessible overview of the knowledge on this topic essential for clinical neurologists. A preoperative multidisciplinary approach involving anaesthesiologists, cardiologists, chest physicians, surgeons and neurologists is crucial. Depolarising muscle relaxants (succinylcholine) should be avoided at all times. The dose of non-depolarising muscle relaxants must be reduced and their effect monitored. Patients with specific mutations in RYR1 (ryanodine receptor 1) and less frequently in CACNA1S (calcium channel, voltage-dependent, L type, alpha 1S subunit) and STAC3 (SH3 and cysteine rich domain 3) are at risk of developing a life-threatening malignant hyperthermia reaction.

A preliminary study of volatile agents or total intravenous anesthesia for neurophysiological monitoring during posterior spinal fusion in adolescents with idiopathic scoliosis

STUDY DESIGN

A prospective randomized controlled trial.

OBJECTIVE

The purpose of this study was to prospectively compare the efficacy of neurophysiological monitoring during general anesthesia with either a total intravenous technique or with the volatile anesthetic agent, desflurane.

SUMMARY OF BACKGROUND DATA

A total intravenous anesthetic technique is generally chosen when neurophysiological monitoring is used as it has been shown to facilitate such monitoring. Despite this, with prolonged infusions of propofol, prolonged awakening times may be seen, which may impact the time required for postoperative neurological assessment or more importantly result in significant delays, should a wake-up test become necessary. To date, there are no prospective trials comparing intravenous techniques with a volatile agent-based anesthetic technique and its effects on neurophysiological monitoring.

METHODS

This prospective study compares somatosensory evoked potential and motor evoked potential monitoring during posterior spinal fusion in 30 adolescents. The patients were randomized to receive a total intravenous technique with propofol-remifentanil or a volatile agent-based technique with desflurane-remifentanil.

RESULTS

The groups were similar with regard to age, weight, height, body mass index, Cobb angle, and distribution of Lenke classifications. No differences were noted in anesthesia time, surgery time, intraoperative fluids, or estimated blood loss between the 2 groups. Time to eye opening, time to following commands, and time to tracheal extubation were shorter in the volatile anesthesia group than the total intravenous anesthesia group. No clinically significant difference was noted in the amplitude or latency of somatosensory evoked potential monitoring. Although statistically significantly greater voltage amplitude was required to generate a motor evoked potential, the voltage amount was within a clinically acceptable range.

CONCLUSION

Our data demonstrate that a volatile agent-based anesthetic regimen is feasible even during neurophysiological monitoring. Advantages include a more rapid awakening and the feasibility of a rapid wake-up test (<5 min) in the event that irreversible changes in neurophysiological monitoring are noted.

LEVEL OF EVIDENCE

2.

Cardiac considerations in the operative management of the patient with Duchenne or Becker muscular dystrophy

Duchenne muscular dystrophy/Becker muscular dystrophy (DMD/BMD) is a progressive multisystem neuromuscular disorder. In addition to the skeletal muscle, the myocardium in the DMD/BMD patient is dystrophin deficient which results in a progressive cardiomyopathy. The myopathic myocardium poses significant risk of increased morbidity and mortality at the time of major surgical procedures. Careful attention must be given to the DMD/BMD patient during the intraoperative and postoperative period. Anesthesia selection is critical and anesthetics should be avoided which have been shown to be harmful in this patient population. Preanesthesia assessment should include cardiac consultation and detailed preoperative evaluation. Intraoperative management needs to insure that the weakened myocardium is not compromised by physiologic changes such as hypotension or major fluid shifts. Finally, attention to the cardiac status of the patient must continue into the postoperative period. The surgical care of the DMD/BMD patient requires a multispecialty approach to insure operative success.

Perioperative care of patients with neuromuscular disease and dysfunction

A variety of different pathologies result in disease phenotypes that are summarized as neuromuscular diseases because they share commonalty in their clinical consequences for the patient: a progressive weakening of the skeletal muscles. Distinct caution and appropriate changes to the anesthetic plan are advised when care is provided during the perioperative period. The choice of anesthetic technique, anesthetic drugs, and neuromuscular blockade always depends on the type of neuromuscular disease and the surgical procedure planned. A clear diagnosis of the underlying disease and sufficient knowledge and understanding of the pathophysiology are of paramount importance to the practitioner and guide optimal perioperative management of affected patients.