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Print version ISSN 0034-7094On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.56 no.6 Campinas Nov./Dec. 2006
Anesthesia in a patient with Steinert disease. Case report*
Anestesia en paciente con enfermedad de Steinert. Relato de caso
Fabiano Souza AraújoI; Roberto Cardoso Bessa JúniorI; Carlos Henrique Viana de Castro, TSAI; Marcos Guilherme Cunha Cruvinel, TSAI; Dalton SantosII
do Hospital Lifecenter
IIColoproctologista do Hospital Lifecenter
CASE REPORT: A man patient, 58 years old, with Steinert disease, who underwent hemorrhoidectomy. Subaracnoid block with hyperbaric bupivacaine (saddle block with puncture at L3-L4 with 0.5% bupivacaine [5 mg]) associated with sedation with propofol (1 µg.mL-1 target using a target-controlled infusion pump). Dypirone (1.5 g) and local infiltration with 0.5% ropivacaine (150 mg) were used for the postoperative analgesia. Intraoperatively, the patient developed myotonic crisis (10 minutes after being placed on the litothomy position) that was controlled by sedation (the target concentration was increased to 1.5 µg.mL-1 and given a bolus of 40 mg). The patient remained stable and was discharged the following day.
CONCLUSIONS: The knowledge about the disease and the proper anesthetic planning are extremely important when managing patients with Steinert disease.
RELATO DEL CASO: Paciente del sexo masculino, 58 años, portador de enfermedad de Steinert, sometido la hemorroidectomía. La conducta anestésica fue raquianestesia con bupivacaína hiperbara (punción L3-L4,con bupivacaína a 0,5% (5 mg) en silla de montar, asociada a la sedación con propofol (blanco de 1 ìg.mL-1 en bomba de infusión blanco controlada). La analgesia postoperatoria fue realizada con dipirona (1,5 g) e infiltración local de ropivacaína a 0,5% (150 mg). El paciente desarrolló, en el intraoperatorio, crisis miotónica (10 minutos después ser colocado en posición de litotomía), que fue controlada con sedación (aumento de la concentración blanco para 1,5 ìg.mL-1 y bolus de 40 mg). Permaneció estable y tuvo alta hospitalaria al día siguiente.
CONCLUSIONES: El conocimiento de la enfermedad y la planificación anestésica son de fundamental importancia en el manoseo de pacientes portadores de la enfermedad de Steinert.
Steinert disease is a neuromuscular disease, with an autossomal dominant inheritance, first described in 1909, and is the most common myotonic syndrome 1. Its prevalence varies from 2 to 14 cases per 100,000, with an incidence of one case for each 8,000 births 2. It usually manifests itself between the 2nd and 4th decades 1.
Myotonia, the presence of persistent contraction of skeletal muscles after voluntary efforts or electrical stimulation has ceased, associated with progressive muscular weakness and muscular atrophy, is the main characteristic of myotonic dystrophy 3,4.
It is considered a multisystem disorder, with a diverse clinical manifestation, such as cataracts, myocardiopathy, changes in atrioventricular conduction, malignant cardiac arrhythmias (ventricular tachycardia and fibrillation), restrictive pulmonary disease, sleep apnea, dysphagia, slow gastric emptying, cholelythiasis, constipation, intestinal pseudobstruction, cognitive dysfunction, mental retardation, frontal baldness, hypothyroidism, primary hypogonadism, infertility, and diabetes mellitus 1,5. Patients with Steinert Disease also have a greater incidence of malignant hyperthermia. Therefore, one should avoid every agent capable of triggering it.
The perioperative management of these patients is a challenge, both due to the increased sensitivity to several anesthetic agents and the risk of cardiorespiratory complications. The objective of this report was to present the anesthetic management of a patient with Steinert disease who underwent hemorrhoidectomy, and to discuss the anesthetic implications in myotonic syndromes.
A man patient, 58 years old, 60 Kg, 1.64 m, with myotonic dystrophy (Steinert disease), treated with phenytoin (100 mg), twice a day, and omeprazole (40 mg), once a day, scheduled for a hemorrhoidectomy. On physical exam the patient was anxious, awake, oriented in time and space, with muscular atrophy of the limbs, trunk, and face. He was incapable of walking, moving about on a wheel chair. He did not present pressure sores. On physical exam, BP = 110 x 60 mmHg, HR = 80 bpm, RR = 28 bpm, and SpO2 = 88% in room air. Important laboratory exams showed normal thyroid and kidney function tests, ABGs with a PaO2 of 67 mmHg, electrocardiogram with a first-degree atrioventricular block, complete right branch block and left anterior hemiblock. Echocardiogram showed good ventricular function, with an ejection fraction of about 0.62, mild mitral regurgitation, and abnormal diastolic relaxation. Chest X-ray showed an elongated aorta with an image suggestive of hiatal hernia.
The patient was monitored as usual (continuous ECG, pulse oxymetry, and non-invasive blood pressure) associated with continuous axillary temperature. The patient received prophylaxis for bacterial endocarditis with IV ampicillin (2 g) after venous cannulation with a 20G catheter, and O2 via nasal canula, which improved SpO2 to 95%.
Prevention of hypothermia was accomplished with a thermic blanket associated with Ringer's lactate preheated to 37°C. Subarachnoid (L3-L4) hyperbaric bupivacaine, 5 mg, was administered with the patient on the sitting position, and he remained in that position for 5 minutes. He was then placed in the lithotomy position. About 15 minutes after he was positioned, the patient complained of discomfort, muscular rigidity in the upper and lower limbs (myotonic contractions without relaxation), associated with decreased hemoglobin saturation (SpO2 = 88%), a reduction in respiratory rate to 6 bpm, and anxiety. The diagnosis of a myotonic crisis was made and it was decided to increase sedation with intermittent doses of propofol (40 mg) and increasing the target concentration to 1.5 µg.mL-1 via target-controlled infusion pump until the end of the surgery, associated temporary assisted ventilation with a face mask. The surgery lasted 40 minutes, and the use of the electric scalpel was avoided. Postoperative analgesia was accomplished with IV dypirone (1.5 g) and local infiltration with 0.5% ropivacaine (150 mg) by the surgeon. Patient remained hemodynamically stable, without other complications. After the surgery, he was in observation for another two hours in the posthanestetic recovery unit, being discharged from the hospital the following day.
Myotonic dystrophy, known as Steinert disease, is the most common muscular dystrophy in adults, being associated with muscular dystrophy and myotonia 6. It is a genetic disease with a dominant autossomal inheritance, and its primary defect is a repetition of the base sequence Cytosine-Thiamine-Guanine in chromosome 19. Its main characteristic is the persistent contraction of the skeletal musculature after any stimulus, i.e., the myotonic crisis or myotonia 3. Myotonia is an intrinsic disorder of the muscles that is not abolished by blockade of the peripheral nerves, not even with neuromuscular blockers. A defect on the sodium-chloride channel on the muscle membrane, which decreases chloride conductance, seems to be the cause of the prolonged contraction 5.
The clinical manifestations affect virtually every system: respiratory (decreased total lung capacity, tendency to aspirate, prone to respiratory depression), muscular (atrophy of the skeletal musculature causing the myotonic facies, dysphagia, muscular weakness), central nervous system (dementia, mental retardation, cerebral atrophy, somnolence, hydrocephalus, cataract), endocrine (diabetes mellitus, thyroid dysfunction, hypogonadism), gastrointestinal (constipation, cholelithiasis, gastroesophageal reflux, intestinal pseudobstruction), hematologic (abnormalities in the membrane of the red blood cells and platelets, increased catabolism by IgG), cardiovascular (myocardiopathy, atrioventricular block, supraventricular and ventricular arrhythmias, myocardial ischemia, mitral valve prolapse, systolic and diastolic ventricular dysfunction) 2-4,7.
The patient reported here presented with advanced muscular atrophy that hindered ambulation, hypoxemia, hiatal hernia, diastolic dysfunction with mitral insufficiency, and first-degree atrioventricular block associated with right branch block and left anterior hemiblock. Perioperative complications are common in those patients, with an incidence between 8.2% and 42.9%, making anesthetic management a challenge 1.
The use of premedication should be avoided due to the greater susceptibility to respiratory depression, unforeseeably response to tranquilizers, and the possibility of triggering malignant hyperthermia, although there are controversies about this last statment 1,3,5. The preferred anesthetic technique is the peripheral nerve block or neuro axis block. One should avoid using general anesthesia due to the inherent ventilatory risks in the postoperative period. Succinylcholine is contraindicated, non-depolarizing neuromuscular blockers have a prolonged action, and anticholinesterase drugs demand caution. Propofol is the hypnotic drug used more often despite reports that it can trigger myotonia and have a prolonged recovery 1.
Triggering a myotonic crisis, which leads to an increase in oxygen consumption and cardiac output, which may cause cardiorespiratory insufficiency, is one of the first things to be avoided 3. Several things can trigger myotonia: hypocalcemia, fear, prolonged fasting, hypoxemia, hypercarbia, increased mechanical pressure, pain, anxiety, adrenergic discharge, electric scalpel, hypothermia, peripheral nerve stimulator, tremors, anticholinesterase drugs, voluntary effort 1,3,5. The development of myotonic crisis in this patient could have been caused by placing the patient in the lithotomy position, fear, and anxiety. When an individual is placed the lithotomy position, there is compression of abdominal organs, elevation of the diaphragm, pulmonary compression, and decreased venous return that can worsen ventilatory mechanics 8. Bolus sedation with propofol allowed for the temporary control of ventilation, fear, and anxiety.
Cardiovascular complications are responsible for the majority of deaths in these patients. Ventricular dysfunction, myocardial ischemia, pulmonary embolism, and sudden death caused by ventricular tachycardia, assistoly, and pulseless electrical activity are the main causes of death. Endomyocardial biopsies show fat infiltration, interstitial fibrosis, focal myocarditis, and endothelial dysfunction 2,4,7. Preoperative electrocardiogram shows conduction disturbances in 50% of the patients, while electrophysiological studies are abnormal in 90% of the cases 3. There are controversies regarding the use of definitive pacemaker in asymptomatic patients (without a history of syncope and an electrocardiogram with conductions disturbances) 2. Transcutaneous and intravenous pacemakers were available in the surgical room, if they were needed.
About 70% of the patients also have changes in esophageal and oropharyngeal motility 9. The presence of hiatal hernia on chest X-ray was an indication that the patient had an increased risk of aspiration, therefore omeprazole was administered.
The knowledge about the disease and proper anesthetic planning allowed the case to be safely managed.
The patient in this case presented advanced muscular atrophy, which made it impossible for him to walk (increasing the risk of thromboembolic complications), hypoxemia (due to muscular weakness and hiatal hernia), hiatal hernia (predisposing the patient to aspiration and atelectasis), diastolic dysfunction with mitral insufficiency (with the risk of cardiopulmonary decompensation after induction of general anesthesia), first degree atrioventricular block associated with right branch block and left anterior hemiblock (that can evolve to total atrioventricular block).
In the case reported here, the following factors might have contributed and caused an adrenergic discharge that would lead to a myotonic crisis: fasting period, anxiety, positioning in the surgical table, and hypoxemia.
Similar to other osteomuscular diseases, Steinert Disease also carries an increased risk of developing malignant hyperthermia and, therefore, the use of known triggering agents should be avoided.
Locoregional anesthesia should be used whenever possible. When it is not possible, one should always consider weaning the patient off mechanical ventilation in the ICU.
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Dr. Fabiano Souza Araújo
Rua Marquês de Maricá, 81/502, Santo Antônio
30350-070 Belo Horizonte, MG
Submitted for publication
02 de março de 2006
Accepted for publication 29 de agosto de 2006
* Received from Hospital Lifecenter, Belo Horizonte, MG