Epidemiology: - risk factors:
- Presence of a known MH causative mutation of RYR1: central core disease, minicore or multicore myopathy core rod myopathy, King-Denborough syndrome, native american myopathy (Lumbee tribe), uniform type I fibers myopathy (CNDMU1), a minority of exertional rhabdomyolysis cases (1).
- Acute anesthesia-induced rhabdomyolysis has long been confused with MH in the literature and some still consider Duchenne muscular dystrophy patients to be at risk of MH. Although the practical endpoint, that is, avoidance of succinylcholine and halogenated agents, is the same, the clinical implications are different because dantrolene is of no help to treat a hyperkalemic cardiac arrest: only the administration of calcium and resuscitation maneuvers are lifesaving. In clinical practice, in the presence of a muscle disease and elevated CK, avoiding halogenated agents and preparing the anesthesia machine in the same way as for MHS patients may be the first choice, but the use of inhalation agents for induction of anesthesia until venous access is obtained is acceptable (1).
Symptoms: all muscle diseases are multiorgan diseases (1). - Heart: is usually affected by the muscular disease. The presence of conduction defects, arrhythmias and cardiomyopathy should be excluded by ECG and echocardiography. The relationship between the severity of cardiac and muscular involvement is unpredictable (1).
- Ventilatory function: is often altered because the diaphragm, intercostal, and accessory muscles are weak. Pharyngeal muscle tone is decreased, and chest infections are frequent (chronic aspiration). Examine the patient for retractions during normal breathing, evaluate the strength of cough, test pulmonary function if possible, and perform night oximetry to dtect obstructive sleep apnea (1).
- Lunge: "difficult airway", schlechte Lungenfunktion (FVC <50%: erhöhtes Komplikationsrisiko; FVC <30%: stark erhöhtes Komplikationsrisiko (präoperativ NPPV?) (ggf. Lungenfunktion)
- ZNS: psychomotorische Retardierung, Epilepsie
- GIT: Reflux, Schluckstörungen, chronische Aspiration, PEG-Sonde
Treatment: - "common pratice" bei Muskeldystrophie: inhalative Einleitung, dann TIVA
- Bekannte Mitochondriopathie:
- minimale Nüchternzeiten
- intra- (bzw. peri-)operative Glucose-Zufuhr/Kontrolle
- keine laktat-haltige Infusion (?)
- Anästhesiologisches Vorgehen bei unklarer NMD ("floppy child"):
- Wahrscheinliche Diagnose aufgrund von Klinik/Anamnese?
- Duchenne Muskeldystrophie: 1:3500 Jungen (X-chromosomal rezessiv), ca 10% der weiblichen Trägerinnen mit leichten Symptomen, proximale Muskelschwäche mit 2-6 Jahren, Rollstuhl mit 10-12 Jahren, Kardiomyopathie beginnend im Teenageralter, oft CK-Erhöhungen
- Mitochondriopathien: 1:4000-5000, geno- und phänotypisch sehr heterogene Erkrankungen, i.d.R. Multiorganerkrankung/-manifestationen, anamnestisch Verschlechterung in katabolen/Stress-Situationen, oft Laborauffälligkeiten (Erhöhung von Laktat, Pyruvat, Acetylcarnitin)
- Generelles Vorgehen (KEIN Succinylcholin wegen erhöhtem Hyperkaliämie/Rhabdomyolyse-Risiko!): inhalative Einleitung zulässig, Aufrechterhaltung inhalativ oder TIVA, KEIN Succinylcholin, Zurückhaltung mit NDMR (verzögertes Ansprechen, verlängerte Wirkung, Monitoring! Amyotrophy, the presence of extrajunctional nicotinic Ach receptors, and intrinsic muscle disease can all influence the response to NDNMBs and also monitoring of neuromuscular transmission; it is thus important to check the patient's baseline response to train-of-four stimulation before administering the NDNMB), gute Analgesie (Regionalanästhesie?) + PONV-Prophylaxe, grosszügige BGA/BZ-Kontrollen, grosszügige postoperative Überwachung bzw. IPS-Indikation
- The causes of excessive muscle weakness in infancy are many, and the diagnosis is usually unknow at the time anesthesia is required. A simple but safe approach is first to ask the pediatrician which diagnosis is the most probable on the basis of clinical examination and mesurement of blood CK and lactates:
- If CKs are elevated, dystrophinopathy is the most frequent diagnosis. Duchenne muscular dystrophy or other pathology possibly at risk of anesthesia-induced rhabdomyolysis could be present, and halogenated agents should be used with great caution.
- If lactates are elevated, mitochondrial disease is most probable. The risk of propofol infusion syndrome may be increased in these patients. Inhalation anesthetics may be used.
- Ketamine supplemented with nitrous oxide, and, if feasible, a regional block may be useful.
References: - Barbara W. Brandom et al. Neuromuscular diseases in children: a practical approach. Pediatric Anesthesia. 2013;23:765-769: full text | pdf.
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