- Email: [email protected]
Successful spinal blockade in a parturient with myotonia congenita
International Journal of Obstetric Anesthesia (2007) 16, 89–97 Ó 2006 Elsevier Ltd. All rights reserved.
CORRESPONDENCE
Successful management of a patient with myotonia congenita for caesarean section using spinal anaesthesia with an amide local anaesthetic and fentanyl has previously been described.3 Problems during general anaesthesia have been reported in patients with myotonia congenita. It has been associated with the occurrence of hypermetabolic events similar to those seen in malignant hyperthermia. Haberer et al. reported the death of a 5-year-old boy with Thomsen’s disease who had delayed clinical features of malignant hyperthermia after general anaesthesia.4 Patients with myotonia congenita are also reported to be at high risk of developing a severe myotonic response with muscle spasms after the use of depolarising muscle relaxants. Two sisters were given general anaesthesia including suxamethonium and both developed total body rigidity.5 A previously undiagnosed 32-year-old female developed life-threatening muscle spasm and secondary respiratory difficulties following a rapid sequence induction with suxamethonium. A diagnosis of myotonia congenita was later confirmed.6 This case also demonstrates that patients may have subclinical muscular symptoms resulting in neither patient nor anaesthetist being aware of the diagnosis before the anaesthetic. Potentially lethal complications can result. A fluctuating type of myotonia congenita that resulted in symptoms only in pregnancy has also been described.7 These case reports have obvious implications for emergency obstetric anaesthesia. Consequently we had formulated a contingency plan for general anaesthesia in the event of failure of regional anaesthesia or if a immediate caesarean section had been required. Given the paucity of published work on myotonia congenita, evidence for the plan was gained from a review of the current literature describing anaesthetic experience in parturients who were susceptible to malignant hyperpyrexia8 and in those with myotonia.1,2 The plan was to avoid depolarising muscle relaxants, volatile agents and those factors known to induce myotonia including cold, shivering and pain on injection of drugs (e.g. propofol). An anaesthetic machine that has been flushed for 20 min with 100% oxygen at 10 L/min with new tubing and fresh CO2 absorbent is suitable for administration of an anaesthetic. Preoxygenation and routine monitoring including capnography and core temperature monitoring were planned before a modified rapid sequence induction. Induction would have been with alfentanil 1-2 mg, propofol 2.5 mg/kg and rocuronium 0.9 mg/kg with cricoid pressure applied.
doi:10.1016/j.ijoa.2006.06.011
Successful spinal blockade in a parturient with myotonia congenita We report a case of a primiparous 22-year-old patient with Thomsen’s disease, the autosomal dominant form of myotonia congenita. She was referred to the obstetric anaesthesia pre-assessment clinic with a plan for an elective caesarean section at 39 weeks’ gestation. She gave a history of muscle stiffness associated with anxiety and after prolonged inactivity. She had had uneventful general anaesthesia at 11 years of age for correction of pes cavus and claw toes. She was on no regular medication and had no known allergies. Examination including airway assessment was unremarkable except for a lumbar lordosis. The lumbar spinous processes were easily palpable. A plan was formulated to perform a lumbar subarachnoid block. She was informed about the procedure including common risks and risk of conversion to general anaesthesia. She was admitted at 39 weeks and received ranitidine. In theatre, intravenous access was obtained with a 16-gauge cannula. A 1000-mL i.v. infusion of Hartmann’s solution and routine monitoring were started. The patient moved to the sitting position and straightforward spinal anaesthesia was performed at the L4/5 interspace via a midline approach with 2.5 mL 0.5% heavy bupivacaine, fentanyl 15 lg and preservative-free morphine 100 lg. The patient was placed in a full left lateral position and 6 mg of ephedrine given. An adequate anaesthetic block was established to T4 bilaterally. Further small boluses of ephedrine were required until delivery. Following delivery of a healthy girl, Syntocinon 5 units and paracetamol were given i.v. Surgery was uneventful with approximately 400 mL blood loss. After surgery the patient was monitored on the postoperative support ward. She required only paracetamol for analgesia and made a good recovery with no exacerbation of her symptoms. Myotonia congenita is one of the group of inherited myotonias. It is caused by a mutation in the skeletal muscle chloride channel gene. More than 30 different mutations have now been identified. This defect results in sustained membrane polarisation. Thomsen’s disease is the autosomal dominant form that is benign and characterised by myotonia (persistent muscular contraction) of all muscle groups.1 Stiffness on initiating voluntary movement is characteristic, and is relieved by exercise (Ôwarm-up phenomenon’). It worsens after a period of rest.2 89
90 International Journal of Obstetric Anesthesia Maintenance of anaesthesia would be with a target propofol infusion and a 50% mixture of nitrous oxide in oxygen used until delivery. Morphine is a suitable analgesic and muscle relaxation may be reversed with an appropriate dose of neostigmine and glycopyrrolate. Myotonia congenita is a rare condition and there is clearly evidence of a complex association with malignant hyperthermia. Although general anaesthesia was not required in our case it was essential to have a plan avoiding known trigger factors for malignant hyperthermia and those factors known to induce myotonia. C. Farrow A. Carling Royal Gwent Hospital, Newport, Wales, UK E-mail: [email protected]
REFERENCES 1. Harvey K, Rosenbaum M D, Jordan D, Miller M D. Malignant hyperthermia and myotonic disorders. Anesthesiol Clin North America 2002; 20: 623–664. 2. Russell S H, Hirsch N P. Anaesthesia and myotonia. Br J Anaesth 1994; 72: 210–216. 3. Arcas M, Sanchez-Ortega J L, Garcia-Munoz M, Alonso B, del Yelmo F, Lopez-Rodriguez F. [Anaesthesia for caesarean delivery in a case of myotonia congenita] (Spanish). Rev Esp Anestesiol Reanim 1996; 43: 147–149. 4. Haberer J P, Fabre F, Rose E. Malignant hyperthermia and myotonia congenita (Thomsen’s disease). Anaesthesia 1989; 44: 166. 5. Heiman-Patterson T, Martino C, Rosenberg H, Fletcher J, Tahmoush A. Malignant hyperthermia in myotonia congenita. Neurology 1988; 38: 810–812. 6. Farbu E, Softeland E, Bindoff L A. Anaesthetic complications associated with myotonia congenita: case study and comparison with other myotonic disorders. Acta Anaesthesiol Scand 2003; 47: 630–634. 7. Lacomis D, Gonzales J T, Giulani M J. Fluctuating clinical myotonia and weakness from Thomsen’s disease occurring only during pregnancies. Clin Neurol Neurosurg 1999; 101: 133–136. 8. Pollock N A, Langton E E. Management of malignant hyperthermia susceptible parturients. Anaesth Intensive Care 1997; 25: 398–407.
doi: 10.1016/j.ijoa.2006.07.003
Combined low-dose spinal-epidural anaesthesia versus single-shot spinal anaesthesia for elective caesarean delivery We read the article on combined low-dose spinal-epidural anaesthesia versus single-shot spinal anaesthesia for elective caesarean delivery with great interest and would like to share our experience.1 Combined spinal-epidural (CSE) anaesthesia is a versatile technique allowing the two components, spinal and epidural, to be used in several ways to achieve optimal anaesthesia.
Over the last 12 years we have anaesthetised approximately 600 cases using a CSE technique. We use the spinal block to facilitate surgery, and top up the epidural catheter for either inadequate sensory block during surgery or to provide postoperative analgesia with diamorphine. In our practice the observed incidence of symptomatic hypotension (nausea, vomiting, and dizziness) is 20-30% and discomfort 10-20%. We have recently adopted the modified sequential CSE technique described by Rawal et al.2 This proposes that a dense spinal block can be achieved in the lower lumbo-sacral region by directing the orifice of a spinal needle caudad. A dense block in the lower lumbo-sacral region is desirable as it results in less unpleasant side effects to the parturient during delivery of the baby, uterine exteriorisation and surgical stimulus to the paracolic gutters. Our technique involves identifying the epidural space with the parturient sitting, using a 16-gauge Tuohy needle with loss of resistance to saline. A 25- or 27-gauge Whitacre spinal needle is introduced into the subarachnoid space through the Tuohy needle with the orifice directed caudad. To achieve a spinal block, we use a mixture of 0.5% hyperbaric bupivacaine 11-13 mg with up to 25 lg of fentanyl. The epidural catheter is inserted and secured, leaving 3 cm in the epidural space. The parturient is then positioned supine with a left lateral tilt. The level of sensory block is assessed with loss of cold sensation using ethyl chloride spray. In the majority of cases we have observed a block to T8, which is easily extended by giving incremental epidural doses. A dose range of 4-6 mL of 0.5% plain bupivacaine is usually required to achieve a loss of cold sensation to T4. The onset of adequate block is achieved without undue delay, because of both epidural volume effect and dose of epidural bupivacaine.3 Motor block is assessed using the modified Bromage scale.4 Our technique appears to have reduced the observed incidence of maternal hypotension, with its associated side effects, and increased maternal tolerance to uterine exteriorisation and paracolic gutter swabbing, especially in those mothers previously delivered by caesarean sections. There also appears to be a reduced need for vasopressors. These observations require further investigation by randomised controlled trial. The current evidence regarding needle type and spread of intrathecal solutions is limited and conflicting.5 The orientation of the Whitacre needle has been used to produce a unilateral block.6 Others have suggested that the orientation of the orifice does not influence the spread of hyperbaric solutions.7,8 Two of these studies were in non-obstetric patients, so extrapolation to obstetrics may not be valid. James et al. demonstrated a more rapid onset sensory block with the orifice of a 24-gauge Sprotte needle directed cephalad using isobaric 0.5% bupivacaine, but no difference in the maximum sensory block height, incidence of hypotension or maternal satisfaction.9
CORRESPONDENCE
Successful management of a patient with myotonia congenita for caesarean section using spinal anaesthesia with an amide local anaesthetic and fentanyl has previously been described.3 Problems during general anaesthesia have been reported in patients with myotonia congenita. It has been associated with the occurrence of hypermetabolic events similar to those seen in malignant hyperthermia. Haberer et al. reported the death of a 5-year-old boy with Thomsen’s disease who had delayed clinical features of malignant hyperthermia after general anaesthesia.4 Patients with myotonia congenita are also reported to be at high risk of developing a severe myotonic response with muscle spasms after the use of depolarising muscle relaxants. Two sisters were given general anaesthesia including suxamethonium and both developed total body rigidity.5 A previously undiagnosed 32-year-old female developed life-threatening muscle spasm and secondary respiratory difficulties following a rapid sequence induction with suxamethonium. A diagnosis of myotonia congenita was later confirmed.6 This case also demonstrates that patients may have subclinical muscular symptoms resulting in neither patient nor anaesthetist being aware of the diagnosis before the anaesthetic. Potentially lethal complications can result. A fluctuating type of myotonia congenita that resulted in symptoms only in pregnancy has also been described.7 These case reports have obvious implications for emergency obstetric anaesthesia. Consequently we had formulated a contingency plan for general anaesthesia in the event of failure of regional anaesthesia or if a immediate caesarean section had been required. Given the paucity of published work on myotonia congenita, evidence for the plan was gained from a review of the current literature describing anaesthetic experience in parturients who were susceptible to malignant hyperpyrexia8 and in those with myotonia.1,2 The plan was to avoid depolarising muscle relaxants, volatile agents and those factors known to induce myotonia including cold, shivering and pain on injection of drugs (e.g. propofol). An anaesthetic machine that has been flushed for 20 min with 100% oxygen at 10 L/min with new tubing and fresh CO2 absorbent is suitable for administration of an anaesthetic. Preoxygenation and routine monitoring including capnography and core temperature monitoring were planned before a modified rapid sequence induction. Induction would have been with alfentanil 1-2 mg, propofol 2.5 mg/kg and rocuronium 0.9 mg/kg with cricoid pressure applied.
doi:10.1016/j.ijoa.2006.06.011
Successful spinal blockade in a parturient with myotonia congenita We report a case of a primiparous 22-year-old patient with Thomsen’s disease, the autosomal dominant form of myotonia congenita. She was referred to the obstetric anaesthesia pre-assessment clinic with a plan for an elective caesarean section at 39 weeks’ gestation. She gave a history of muscle stiffness associated with anxiety and after prolonged inactivity. She had had uneventful general anaesthesia at 11 years of age for correction of pes cavus and claw toes. She was on no regular medication and had no known allergies. Examination including airway assessment was unremarkable except for a lumbar lordosis. The lumbar spinous processes were easily palpable. A plan was formulated to perform a lumbar subarachnoid block. She was informed about the procedure including common risks and risk of conversion to general anaesthesia. She was admitted at 39 weeks and received ranitidine. In theatre, intravenous access was obtained with a 16-gauge cannula. A 1000-mL i.v. infusion of Hartmann’s solution and routine monitoring were started. The patient moved to the sitting position and straightforward spinal anaesthesia was performed at the L4/5 interspace via a midline approach with 2.5 mL 0.5% heavy bupivacaine, fentanyl 15 lg and preservative-free morphine 100 lg. The patient was placed in a full left lateral position and 6 mg of ephedrine given. An adequate anaesthetic block was established to T4 bilaterally. Further small boluses of ephedrine were required until delivery. Following delivery of a healthy girl, Syntocinon 5 units and paracetamol were given i.v. Surgery was uneventful with approximately 400 mL blood loss. After surgery the patient was monitored on the postoperative support ward. She required only paracetamol for analgesia and made a good recovery with no exacerbation of her symptoms. Myotonia congenita is one of the group of inherited myotonias. It is caused by a mutation in the skeletal muscle chloride channel gene. More than 30 different mutations have now been identified. This defect results in sustained membrane polarisation. Thomsen’s disease is the autosomal dominant form that is benign and characterised by myotonia (persistent muscular contraction) of all muscle groups.1 Stiffness on initiating voluntary movement is characteristic, and is relieved by exercise (Ôwarm-up phenomenon’). It worsens after a period of rest.2 89
90 International Journal of Obstetric Anesthesia Maintenance of anaesthesia would be with a target propofol infusion and a 50% mixture of nitrous oxide in oxygen used until delivery. Morphine is a suitable analgesic and muscle relaxation may be reversed with an appropriate dose of neostigmine and glycopyrrolate. Myotonia congenita is a rare condition and there is clearly evidence of a complex association with malignant hyperthermia. Although general anaesthesia was not required in our case it was essential to have a plan avoiding known trigger factors for malignant hyperthermia and those factors known to induce myotonia. C. Farrow A. Carling Royal Gwent Hospital, Newport, Wales, UK E-mail: [email protected]
REFERENCES 1. Harvey K, Rosenbaum M D, Jordan D, Miller M D. Malignant hyperthermia and myotonic disorders. Anesthesiol Clin North America 2002; 20: 623–664. 2. Russell S H, Hirsch N P. Anaesthesia and myotonia. Br J Anaesth 1994; 72: 210–216. 3. Arcas M, Sanchez-Ortega J L, Garcia-Munoz M, Alonso B, del Yelmo F, Lopez-Rodriguez F. [Anaesthesia for caesarean delivery in a case of myotonia congenita] (Spanish). Rev Esp Anestesiol Reanim 1996; 43: 147–149. 4. Haberer J P, Fabre F, Rose E. Malignant hyperthermia and myotonia congenita (Thomsen’s disease). Anaesthesia 1989; 44: 166. 5. Heiman-Patterson T, Martino C, Rosenberg H, Fletcher J, Tahmoush A. Malignant hyperthermia in myotonia congenita. Neurology 1988; 38: 810–812. 6. Farbu E, Softeland E, Bindoff L A. Anaesthetic complications associated with myotonia congenita: case study and comparison with other myotonic disorders. Acta Anaesthesiol Scand 2003; 47: 630–634. 7. Lacomis D, Gonzales J T, Giulani M J. Fluctuating clinical myotonia and weakness from Thomsen’s disease occurring only during pregnancies. Clin Neurol Neurosurg 1999; 101: 133–136. 8. Pollock N A, Langton E E. Management of malignant hyperthermia susceptible parturients. Anaesth Intensive Care 1997; 25: 398–407.
doi: 10.1016/j.ijoa.2006.07.003
Combined low-dose spinal-epidural anaesthesia versus single-shot spinal anaesthesia for elective caesarean delivery We read the article on combined low-dose spinal-epidural anaesthesia versus single-shot spinal anaesthesia for elective caesarean delivery with great interest and would like to share our experience.1 Combined spinal-epidural (CSE) anaesthesia is a versatile technique allowing the two components, spinal and epidural, to be used in several ways to achieve optimal anaesthesia.
Over the last 12 years we have anaesthetised approximately 600 cases using a CSE technique. We use the spinal block to facilitate surgery, and top up the epidural catheter for either inadequate sensory block during surgery or to provide postoperative analgesia with diamorphine. In our practice the observed incidence of symptomatic hypotension (nausea, vomiting, and dizziness) is 20-30% and discomfort 10-20%. We have recently adopted the modified sequential CSE technique described by Rawal et al.2 This proposes that a dense spinal block can be achieved in the lower lumbo-sacral region by directing the orifice of a spinal needle caudad. A dense block in the lower lumbo-sacral region is desirable as it results in less unpleasant side effects to the parturient during delivery of the baby, uterine exteriorisation and surgical stimulus to the paracolic gutters. Our technique involves identifying the epidural space with the parturient sitting, using a 16-gauge Tuohy needle with loss of resistance to saline. A 25- or 27-gauge Whitacre spinal needle is introduced into the subarachnoid space through the Tuohy needle with the orifice directed caudad. To achieve a spinal block, we use a mixture of 0.5% hyperbaric bupivacaine 11-13 mg with up to 25 lg of fentanyl. The epidural catheter is inserted and secured, leaving 3 cm in the epidural space. The parturient is then positioned supine with a left lateral tilt. The level of sensory block is assessed with loss of cold sensation using ethyl chloride spray. In the majority of cases we have observed a block to T8, which is easily extended by giving incremental epidural doses. A dose range of 4-6 mL of 0.5% plain bupivacaine is usually required to achieve a loss of cold sensation to T4. The onset of adequate block is achieved without undue delay, because of both epidural volume effect and dose of epidural bupivacaine.3 Motor block is assessed using the modified Bromage scale.4 Our technique appears to have reduced the observed incidence of maternal hypotension, with its associated side effects, and increased maternal tolerance to uterine exteriorisation and paracolic gutter swabbing, especially in those mothers previously delivered by caesarean sections. There also appears to be a reduced need for vasopressors. These observations require further investigation by randomised controlled trial. The current evidence regarding needle type and spread of intrathecal solutions is limited and conflicting.5 The orientation of the Whitacre needle has been used to produce a unilateral block.6 Others have suggested that the orientation of the orifice does not influence the spread of hyperbaric solutions.7,8 Two of these studies were in non-obstetric patients, so extrapolation to obstetrics may not be valid. James et al. demonstrated a more rapid onset sensory block with the orifice of a 24-gauge Sprotte needle directed cephalad using isobaric 0.5% bupivacaine, but no difference in the maximum sensory block height, incidence of hypotension or maternal satisfaction.9