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Urgent caesarean section in a patient with myotonic dystrophy: a case report and review
Infernutional Journal of Obstetric Anesthesia (1996) S,272-274 0 1996 Pearson Professional Ltd
CASE REPORT
AND REVIEW
Urgent caesarean section in a patient with myotonic dystrophy: a case report and review I? J. O’Connor, L. D. Caldicott, I? Braithwaite Department of Anaesthesia, Leeds General Infirmary, Leeds,
INTRODUCTION
UK
unaffected. Although the anaesthetic department had been notified prior to her acute presentation she had not been fully assessedand no specific tests of muscle function had been performed. She denied any cardiovascular or respiratory symptoms and only experienced muscle stiffness in cold weather. Examination revealed the characteristic facies of myotonic dystrophy with frontal balding and ptosis. There was a marked inability to relax her hand muscles once a fist had been m a d e and she had to prise her fingers apart with the other hand. Blood pressure was 140/95 m m Hg and she had proteinuria of 7.25 g/day with peripheral oedema. An electrocardiogram (ECG) was norm a l. Coagulation studies were normal and her platelet count was 210 x log/l. A combined spinal/epidural technique was suggestedand agreedby the patient. The patient was premeditated with ranitidine 150 m g and given 30 m l of 0.3 M sodium citrate in the anaesthetic room. Before starting she appeared anxious and was shivering but denied any symptoms of increased muscle tone. M o n itoring included ECG, non-invasive blood pressure, pulse oximetry and hourly urine output measurement. A 14 gauge intravenous cannula was inserted under local anaesthesia and 1 L of normal saline given as a preload. An epidural catheter was then sited at the L34 interspace in the sitting position and a test dose of 4 m l 1.5% lignocaine produced no effect after 5 m in. A subarachnoid block was then performed in the sitting position, at L4-5, using a 27 gaugeW h itacre needle and 3 m l of hyperbaric bupivacaine 0.5%. A complete sensory block bilaterally to T5 and motor block of the lower limbs developed within 10 m in. Intraoperatively the patient received a total of 15 m g ephedrine to m a intain blood pressure,cephradine 1 g, Syntocinon 5 iu after cord clamping and 10 m g metoclopramide for nausea. A live m a le weighing 3320 g was delivered with an Apgar score of 8 at 1 m in and 10 at 5 m in. The maternal blood pressure and pulse remained stable throughout the procedure and
Myotonic dystrophy is a degenerativedisease involving skeletal, cardiac and smooth muscle. It is an autosomal d o m inant condition and has a prevalence of about 1:20 000.’The clinical syndrome usually m a n ifests itself in early adulthood and is characterized by an abnormal delay in relaxation of skeletal muscle and wasting and weakness of certain muscle groups. Ptosis, frontal balding, cardiomyopathy, cardiac rhythm disorders, glucose intolerance, gonadal atrophy and a progressive decline in intellect can also occur. Pregnancy is uncommon in this condition due to subfertility but is frequently complicated by premature and prolonged labour, uterine atony and postpartum haemorrhage,2 with operative delivery and anaesthetic assistanceoften required. W e describe the uneventful anaesthetic management of a patient presenting for urgent caesareansection under combined spinal and epidural anaesthesiaand review the literature on this subject. CASE HISTORY A 26-year-old woman presented at 36 weeks gestation for urgent caesareansection becauseof preeclampsia. A diagnosis of myotonic dystrophy had been m a d e at 13 years of age. Her mother and two cousins also had the condition. She had undergone a termination of pregnancy under general anaesthesia 2 years previously after antenatal diagnosis using chorionic villous sampling and gene analysis had shown the fetus to be carrying the myotonic dystrophy gene. In this pregnancy antenatal diagnosis had shown the baby to be F? J. O ’Connor, L. D. Caldicolt, P. Braithwaite, Department of Anaesthesia, Leeds General Infirmary, Great George Street, Leeds, LSl 3EX Correspondence to: Dr P. J. O ’Connor, Department of Anaesthesia, Queens Medical Centre, Nottingham, NG7 2UH 272
Urgent caesarean section in a patient with myotonic dystrophy uterine contraction was well maintained without the need for further oxytocic agents. Blood loss was estimated to be 550 ml. Increased muscle tone was not apparent intraoperatively and the patient remained pain free. At the end of the operation she received diclofenac 100 mg per rectum and was transferred to a high-dependency area for postoperative monitoring. Postoperatively she received a total of 15 mg intramuscular morphine over 6 h and oral coproxamol. Her recovery was marred by a period of depression and inability to cope with the child necessitating psychiatric referral. She was discharged home 8 days postoperatively.
DISCUSSION
Myotonic dystrophy in the female is associated with sub-fertility. This is often attributed to primary ovarian insufficiency and is analogous to the testicular atrophy that is seen in an affected male. Once pregnant, there is an increased risk of obstetric and neonatal complications.3x4 Spontaneous abortion and polyhydramnios can occur, the latter usually indicating an affected fetus with severe muscular dysfunction and impaired swallowing. Labour can also be complicated by abnormal presentation, premature onset, poor progress and prolonged second stage due to poor voluntary maternal assistance and abnormal uterine contraction. Postpartum haemorrhage can also occur due to uterine atony which may be unresponsive to oxytocics and may only be treatable by hysterectomy.5 Bleeding problems should therefore be anticipated and at least 4 units of blood should be immediately available.5m7 Pregnancy also appears to exacerbate the disease and lead to a worsening of symptoms. However, this was not reported in our patient. Such deterioration could be due to the increase in progesterone levels that can affect membrane potentials by altering potassium ion ratios across the cell membrane.* At term, the incidence of instrumental delivery is high and therefore anaesthetic involvement is likely. Affected infants have a high incidence of respiratory infections, difficulties feeding and sucking and may have musculoskeletal malformations. In the case of a child with this condition the affected parent is almost always the mother. Difference in fertility between the sexes is insufficient to explain this finding suggesting the possible role of a maternal circulating factor on the genetically predisposed child.4 This is supported by the fact that the child often improves after the first few weeks of life. Our patient had undergone a previous termination after in-utero screening showed an affected fetus. Screening in this pregnancy had shown a normal child.
273
Avoidance of a myotonic crisis with sustained, generalized muscle contracture is important. During crises both spontaneous and controlled ventilation can be severely compromized9 and hypoxia can occur. Laryngeal spasm can occur and cause death. Myotonic contractions may follow surgical stimulation, diathermy, shivering, the use of depolarizing muscle relaxants and anticholinesterase agents.2Jg’3 Deep levels of general anaesthesia seem to prevent or reduce the incidence of crises. The use of diathermy should be kept to a minimum and the patient kept as warm as possible with warmed intravenous fluids.2 Direct injection of local anaesthetic into myotonic muscle can relieve spasm in individual muscles but there is no agreed treatment for a generalized spasm. Class I antiarrhythmic agents such as phenytoin and procainamide have been usedI and intravenous quinine may be helpful.r5 Respiratory failure is a major cause of postoperative morbidity. ‘OVital capacity and expiratory reserve volumes are frequently reducedI and there is a high risk of pneumonia after general anaesthesia. The respiratory problems may be compounded by increased sensitivity to the effects of intravenous general anaesthetics, opioids and other sedative drugs, and possibly the non-depolarizing muscle relaxants.” In our case respiratory function tests were not performed as the patient presented late and had no symptoms or signs of respiratory disease. Dystrophic involvement of the cardiac conducting tissues may result in varying degrees of heart-block and arrhythmias. I8 Cardiomyopathy can also occur and may be aggravated by blood volume changes during pregnancy and delivery. The presence of preeclampsia, as in our case, may further complicate this situation necessitating careful perioperative fluid management and continued monitoring into the postoperative period. The risk of regurgitation and aspiration at induction and postoperatively following general anaesthesia for caesarean section is increased due to laryngeal weakness and poor oesophageal motility. Uterine contractility may be ineffective and refractory uterine atony associated with post-partum haemorrhage is a recognized problem.“6 The choice between general and regional anaesthesia for operative delivery is unclear although both have been used successfully. In extreme emergencies general anaesthesia is quicker but in such circumstances a non-depolarizing muscle relaxant should be used and suxamethonium avoided. Successful use of a priming dose of atracurium to allow quicker onset of paralysis has been reported,19 as has a single dose of vecuronium.‘j The patients may be extremely sensitive to the central depressant effects of the intravenous
274 International Journal of Obstetric Anesthesia induction agents and an exaggerated anaesthetic effect with prolonged apnoea has been reported after both thiopentone*O and propofol.21 We chose regional anaesthesia to avoid problems with muscle relaxants, general anaesthetic agents and aspiration, as mentioned above, but regional anaesthesia has hazards of its own. There is an increased incidence of shivering associated with regional anaesthesia which may initiate generalized myotonia. The patient in our case was shivering before the start of any anaesthetic technique, probably due to anxiety, but this did not seem to cause any problems. Measures should be taken to reduce the incidence of shivering such as warming intravenous fluids22 and local anaesthetics. A high thoracic block may be hazardous in a patient with reduced cardiac or respiratory reserve and careful monitoring of the extent of the block is essential. Epidura12”26 and spinal anaesthesia7 have both been used successfully in myotonic dystrophy. Inadequate analgesia7 and uncontrollable haemorrhage have both been described under epidural anaesthesia, necessitating progression to general anaesthesia and this possibility should be anticipated. The combined epidurallspinal technique combines the reliable, dense analgesia of a subarachnoid block with the back-up of an epidural catheter should the block be insufficient or the surgery prolonged. Epidurally administered opioids limit postoperative shivering, which may be detrimental to these patients, and may also provide postoperative analgesia. Sufentanil has been given by this route25 mainly for its anti-shivering effects. Due to the potentially increased sensitivity to analgesics and the possibility of late-onset respiratory depression we chose not to use opioids epidurally. Our patient had reported no adverse effects from intramuscular morphine given previously for postoperative pain relief and this was therefore used again with no problems in this case. The incidence of problems reflects the severity of the disease and the relatively mild symptoms reported by the patient may have led to the uncomplicated nature of our case. REFERENCES
1, Gamer-Medwin D. Clinical features and classification of muscular dvstrophies. Br Med Bull 1980: 36: 109-l 15. 2. Russell S H, Hirich N P. Anaesthesia and Myotonia. Br .I Anaesth 1994; 72: 210-216.
3. Webb D, Muir I, Faulkner J, Johnson G. Myotonia dystrophica: obstetric complications. Am J Obstet Gynecol 1978; 132: 265-270 4. Shore R N. Myotonic dystrophy: hazards of pregnancy and infancy. Dev Med Child Neurol 1975; 17: 356361. 5. Hook R, Anderson E F, Noto P. Anesthetic management of a parturient with myotonia atrophica Anesthesiology 1975; 43: 689-692. 6. Blumgart C H, Hughes D G, Redfern N. Obstetric anaesthesia in dystrophia myotonica. Anaesthesia 1990; 45: 26-29. I. Cope D K, Miller J N. Local and spinal block anesthesia for cesarean section in a patient with myotonic dystrophy. Anesth Analg 1986; 65: 687690 8. Hopkins A, Wray S. The effect of pregnancy on dystrophia myotonica. Neurology 1967; 17: 166167. 9. Miller J D, Lee C. Muscle diseases. In: Katz J, Benumof J, Kadis L B, eds. Anesthesia and uncommon diseases. 3rd ed. Philadelphia: W. B. Saunders Co., 1990: 596-600. 10. Aldridge L M. Anaesthetic problems in myotonic dystrophy. Br J Anaesth 1985; 57: 1119-l 130. 11. Mitchell M M, Ali H H, Savarese J J. Myotonia and neuromuscular blocking agents. Anesthesiology 1978; 49: 4448. 12. Patterson I S. Generalised myotonia following suxamethonium. A case report. Br J Anaesth 1962; 34: 340-342. 13. Theil R E. The myotonic response to suxamethonium. Br J Anaesth 1967; 39: 815-820. 14. Editorial. Treatment of Myotonia. Lancet 1987; 1242-1243. 15. Kaufman L. Anaesthesia in Dystrophia Myotonica. A review of the hazards of anaesthesia. Proc R Sot Med 1959; 53: 183-188. 16. Gillam P M S, Heaf P J D, Kaufman L, Lucas B G B. Respiration in dystrophia myotonica. Thorax 1964; 19: 112-120. 17. Azar I. The response of patients with neuromuscular disorders to muscular relaxants: a review. Anesthesiology 1984; 61: 173-187. 18. Perlof J K, Stevenson W G, Roberts N K, Cabeen W, Weiss J. Cardiac involvement in myotonic dystrophy (Steinert’s disease): a prospective study of 25 patients. Am J Cardiol 1984; 54: 10741081. 19. Walpole A R, Ross A W. Acute cord prolapse in an obstetric patient with myotonia dystrophica. Anaesth Intensive Care 1992; 20: 526528. 20. Pollard B J, Young T M. Anaesthesia in myotonia dystrophica. Anaesthesia 1989; 44: 699. 21. Speedy H. Exaggerated physiological responses to propofol in myotonic dystrophy. Br J Anaesth 1990; 64: 110-l 12. 22. Workhoven M N. Intravenous fluid temperature, shivering and the parturient. Anesth Analg 1986; 65: 496498. 23. Walmsley A J, Giescke A H, Lipton J M. Contribution of extradural temperature to shivering during extradural anaesthesia. Br J Anaesth 1986; 58: 1130-l 134. 24. Harris M N E. Extradural analgesia and dystrophia myotonia. Anaesthesia 1984; 39: 1032-1033. 25. Paterson R A, Tousignant M, Skene D S. Caesarean section for twins in a patient with myotonic dystrophy. 1985; 32: 4 18421. Can Anaesth Sot J 26. Camann W R, Johnson M D. Anesthetic management of a parturient with myotonia dystrophica: a case report. Reg Anesth 1990; 15: 41-43.
CASE REPORT
AND REVIEW
Urgent caesarean section in a patient with myotonic dystrophy: a case report and review I? J. O’Connor, L. D. Caldicott, I? Braithwaite Department of Anaesthesia, Leeds General Infirmary, Leeds,
INTRODUCTION
UK
unaffected. Although the anaesthetic department had been notified prior to her acute presentation she had not been fully assessedand no specific tests of muscle function had been performed. She denied any cardiovascular or respiratory symptoms and only experienced muscle stiffness in cold weather. Examination revealed the characteristic facies of myotonic dystrophy with frontal balding and ptosis. There was a marked inability to relax her hand muscles once a fist had been m a d e and she had to prise her fingers apart with the other hand. Blood pressure was 140/95 m m Hg and she had proteinuria of 7.25 g/day with peripheral oedema. An electrocardiogram (ECG) was norm a l. Coagulation studies were normal and her platelet count was 210 x log/l. A combined spinal/epidural technique was suggestedand agreedby the patient. The patient was premeditated with ranitidine 150 m g and given 30 m l of 0.3 M sodium citrate in the anaesthetic room. Before starting she appeared anxious and was shivering but denied any symptoms of increased muscle tone. M o n itoring included ECG, non-invasive blood pressure, pulse oximetry and hourly urine output measurement. A 14 gauge intravenous cannula was inserted under local anaesthesia and 1 L of normal saline given as a preload. An epidural catheter was then sited at the L34 interspace in the sitting position and a test dose of 4 m l 1.5% lignocaine produced no effect after 5 m in. A subarachnoid block was then performed in the sitting position, at L4-5, using a 27 gaugeW h itacre needle and 3 m l of hyperbaric bupivacaine 0.5%. A complete sensory block bilaterally to T5 and motor block of the lower limbs developed within 10 m in. Intraoperatively the patient received a total of 15 m g ephedrine to m a intain blood pressure,cephradine 1 g, Syntocinon 5 iu after cord clamping and 10 m g metoclopramide for nausea. A live m a le weighing 3320 g was delivered with an Apgar score of 8 at 1 m in and 10 at 5 m in. The maternal blood pressure and pulse remained stable throughout the procedure and
Myotonic dystrophy is a degenerativedisease involving skeletal, cardiac and smooth muscle. It is an autosomal d o m inant condition and has a prevalence of about 1:20 000.’The clinical syndrome usually m a n ifests itself in early adulthood and is characterized by an abnormal delay in relaxation of skeletal muscle and wasting and weakness of certain muscle groups. Ptosis, frontal balding, cardiomyopathy, cardiac rhythm disorders, glucose intolerance, gonadal atrophy and a progressive decline in intellect can also occur. Pregnancy is uncommon in this condition due to subfertility but is frequently complicated by premature and prolonged labour, uterine atony and postpartum haemorrhage,2 with operative delivery and anaesthetic assistanceoften required. W e describe the uneventful anaesthetic management of a patient presenting for urgent caesareansection under combined spinal and epidural anaesthesiaand review the literature on this subject. CASE HISTORY A 26-year-old woman presented at 36 weeks gestation for urgent caesareansection becauseof preeclampsia. A diagnosis of myotonic dystrophy had been m a d e at 13 years of age. Her mother and two cousins also had the condition. She had undergone a termination of pregnancy under general anaesthesia 2 years previously after antenatal diagnosis using chorionic villous sampling and gene analysis had shown the fetus to be carrying the myotonic dystrophy gene. In this pregnancy antenatal diagnosis had shown the baby to be F? J. O ’Connor, L. D. Caldicolt, P. Braithwaite, Department of Anaesthesia, Leeds General Infirmary, Great George Street, Leeds, LSl 3EX Correspondence to: Dr P. J. O ’Connor, Department of Anaesthesia, Queens Medical Centre, Nottingham, NG7 2UH 272
Urgent caesarean section in a patient with myotonic dystrophy uterine contraction was well maintained without the need for further oxytocic agents. Blood loss was estimated to be 550 ml. Increased muscle tone was not apparent intraoperatively and the patient remained pain free. At the end of the operation she received diclofenac 100 mg per rectum and was transferred to a high-dependency area for postoperative monitoring. Postoperatively she received a total of 15 mg intramuscular morphine over 6 h and oral coproxamol. Her recovery was marred by a period of depression and inability to cope with the child necessitating psychiatric referral. She was discharged home 8 days postoperatively.
DISCUSSION
Myotonic dystrophy in the female is associated with sub-fertility. This is often attributed to primary ovarian insufficiency and is analogous to the testicular atrophy that is seen in an affected male. Once pregnant, there is an increased risk of obstetric and neonatal complications.3x4 Spontaneous abortion and polyhydramnios can occur, the latter usually indicating an affected fetus with severe muscular dysfunction and impaired swallowing. Labour can also be complicated by abnormal presentation, premature onset, poor progress and prolonged second stage due to poor voluntary maternal assistance and abnormal uterine contraction. Postpartum haemorrhage can also occur due to uterine atony which may be unresponsive to oxytocics and may only be treatable by hysterectomy.5 Bleeding problems should therefore be anticipated and at least 4 units of blood should be immediately available.5m7 Pregnancy also appears to exacerbate the disease and lead to a worsening of symptoms. However, this was not reported in our patient. Such deterioration could be due to the increase in progesterone levels that can affect membrane potentials by altering potassium ion ratios across the cell membrane.* At term, the incidence of instrumental delivery is high and therefore anaesthetic involvement is likely. Affected infants have a high incidence of respiratory infections, difficulties feeding and sucking and may have musculoskeletal malformations. In the case of a child with this condition the affected parent is almost always the mother. Difference in fertility between the sexes is insufficient to explain this finding suggesting the possible role of a maternal circulating factor on the genetically predisposed child.4 This is supported by the fact that the child often improves after the first few weeks of life. Our patient had undergone a previous termination after in-utero screening showed an affected fetus. Screening in this pregnancy had shown a normal child.
273
Avoidance of a myotonic crisis with sustained, generalized muscle contracture is important. During crises both spontaneous and controlled ventilation can be severely compromized9 and hypoxia can occur. Laryngeal spasm can occur and cause death. Myotonic contractions may follow surgical stimulation, diathermy, shivering, the use of depolarizing muscle relaxants and anticholinesterase agents.2Jg’3 Deep levels of general anaesthesia seem to prevent or reduce the incidence of crises. The use of diathermy should be kept to a minimum and the patient kept as warm as possible with warmed intravenous fluids.2 Direct injection of local anaesthetic into myotonic muscle can relieve spasm in individual muscles but there is no agreed treatment for a generalized spasm. Class I antiarrhythmic agents such as phenytoin and procainamide have been usedI and intravenous quinine may be helpful.r5 Respiratory failure is a major cause of postoperative morbidity. ‘OVital capacity and expiratory reserve volumes are frequently reducedI and there is a high risk of pneumonia after general anaesthesia. The respiratory problems may be compounded by increased sensitivity to the effects of intravenous general anaesthetics, opioids and other sedative drugs, and possibly the non-depolarizing muscle relaxants.” In our case respiratory function tests were not performed as the patient presented late and had no symptoms or signs of respiratory disease. Dystrophic involvement of the cardiac conducting tissues may result in varying degrees of heart-block and arrhythmias. I8 Cardiomyopathy can also occur and may be aggravated by blood volume changes during pregnancy and delivery. The presence of preeclampsia, as in our case, may further complicate this situation necessitating careful perioperative fluid management and continued monitoring into the postoperative period. The risk of regurgitation and aspiration at induction and postoperatively following general anaesthesia for caesarean section is increased due to laryngeal weakness and poor oesophageal motility. Uterine contractility may be ineffective and refractory uterine atony associated with post-partum haemorrhage is a recognized problem.“6 The choice between general and regional anaesthesia for operative delivery is unclear although both have been used successfully. In extreme emergencies general anaesthesia is quicker but in such circumstances a non-depolarizing muscle relaxant should be used and suxamethonium avoided. Successful use of a priming dose of atracurium to allow quicker onset of paralysis has been reported,19 as has a single dose of vecuronium.‘j The patients may be extremely sensitive to the central depressant effects of the intravenous
274 International Journal of Obstetric Anesthesia induction agents and an exaggerated anaesthetic effect with prolonged apnoea has been reported after both thiopentone*O and propofol.21 We chose regional anaesthesia to avoid problems with muscle relaxants, general anaesthetic agents and aspiration, as mentioned above, but regional anaesthesia has hazards of its own. There is an increased incidence of shivering associated with regional anaesthesia which may initiate generalized myotonia. The patient in our case was shivering before the start of any anaesthetic technique, probably due to anxiety, but this did not seem to cause any problems. Measures should be taken to reduce the incidence of shivering such as warming intravenous fluids22 and local anaesthetics. A high thoracic block may be hazardous in a patient with reduced cardiac or respiratory reserve and careful monitoring of the extent of the block is essential. Epidura12”26 and spinal anaesthesia7 have both been used successfully in myotonic dystrophy. Inadequate analgesia7 and uncontrollable haemorrhage have both been described under epidural anaesthesia, necessitating progression to general anaesthesia and this possibility should be anticipated. The combined epidurallspinal technique combines the reliable, dense analgesia of a subarachnoid block with the back-up of an epidural catheter should the block be insufficient or the surgery prolonged. Epidurally administered opioids limit postoperative shivering, which may be detrimental to these patients, and may also provide postoperative analgesia. Sufentanil has been given by this route25 mainly for its anti-shivering effects. Due to the potentially increased sensitivity to analgesics and the possibility of late-onset respiratory depression we chose not to use opioids epidurally. Our patient had reported no adverse effects from intramuscular morphine given previously for postoperative pain relief and this was therefore used again with no problems in this case. The incidence of problems reflects the severity of the disease and the relatively mild symptoms reported by the patient may have led to the uncomplicated nature of our case. REFERENCES
1, Gamer-Medwin D. Clinical features and classification of muscular dvstrophies. Br Med Bull 1980: 36: 109-l 15. 2. Russell S H, Hirich N P. Anaesthesia and Myotonia. Br .I Anaesth 1994; 72: 210-216.
3. Webb D, Muir I, Faulkner J, Johnson G. Myotonia dystrophica: obstetric complications. Am J Obstet Gynecol 1978; 132: 265-270 4. Shore R N. Myotonic dystrophy: hazards of pregnancy and infancy. Dev Med Child Neurol 1975; 17: 356361. 5. Hook R, Anderson E F, Noto P. Anesthetic management of a parturient with myotonia atrophica Anesthesiology 1975; 43: 689-692. 6. Blumgart C H, Hughes D G, Redfern N. Obstetric anaesthesia in dystrophia myotonica. Anaesthesia 1990; 45: 26-29. I. Cope D K, Miller J N. Local and spinal block anesthesia for cesarean section in a patient with myotonic dystrophy. Anesth Analg 1986; 65: 687690 8. Hopkins A, Wray S. The effect of pregnancy on dystrophia myotonica. Neurology 1967; 17: 166167. 9. Miller J D, Lee C. Muscle diseases. In: Katz J, Benumof J, Kadis L B, eds. Anesthesia and uncommon diseases. 3rd ed. Philadelphia: W. B. Saunders Co., 1990: 596-600. 10. Aldridge L M. Anaesthetic problems in myotonic dystrophy. Br J Anaesth 1985; 57: 1119-l 130. 11. Mitchell M M, Ali H H, Savarese J J. Myotonia and neuromuscular blocking agents. Anesthesiology 1978; 49: 4448. 12. Patterson I S. Generalised myotonia following suxamethonium. A case report. Br J Anaesth 1962; 34: 340-342. 13. Theil R E. The myotonic response to suxamethonium. Br J Anaesth 1967; 39: 815-820. 14. Editorial. Treatment of Myotonia. Lancet 1987; 1242-1243. 15. Kaufman L. Anaesthesia in Dystrophia Myotonica. A review of the hazards of anaesthesia. Proc R Sot Med 1959; 53: 183-188. 16. Gillam P M S, Heaf P J D, Kaufman L, Lucas B G B. Respiration in dystrophia myotonica. Thorax 1964; 19: 112-120. 17. Azar I. The response of patients with neuromuscular disorders to muscular relaxants: a review. Anesthesiology 1984; 61: 173-187. 18. Perlof J K, Stevenson W G, Roberts N K, Cabeen W, Weiss J. Cardiac involvement in myotonic dystrophy (Steinert’s disease): a prospective study of 25 patients. Am J Cardiol 1984; 54: 10741081. 19. Walpole A R, Ross A W. Acute cord prolapse in an obstetric patient with myotonia dystrophica. Anaesth Intensive Care 1992; 20: 526528. 20. Pollard B J, Young T M. Anaesthesia in myotonia dystrophica. Anaesthesia 1989; 44: 699. 21. Speedy H. Exaggerated physiological responses to propofol in myotonic dystrophy. Br J Anaesth 1990; 64: 110-l 12. 22. Workhoven M N. Intravenous fluid temperature, shivering and the parturient. Anesth Analg 1986; 65: 496498. 23. Walmsley A J, Giescke A H, Lipton J M. Contribution of extradural temperature to shivering during extradural anaesthesia. Br J Anaesth 1986; 58: 1130-l 134. 24. Harris M N E. Extradural analgesia and dystrophia myotonia. Anaesthesia 1984; 39: 1032-1033. 25. Paterson R A, Tousignant M, Skene D S. Caesarean section for twins in a patient with myotonic dystrophy. 1985; 32: 4 18421. Can Anaesth Sot J 26. Camann W R, Johnson M D. Anesthetic management of a parturient with myotonia dystrophica: a case report. Reg Anesth 1990; 15: 41-43.