Patients with spinal muscular atrophy can present a challenge to anesthetic management for several reasons including hypersensitivity to neuromuscular blocking agents, prolonged muscle weakness, abnormal spinal anatomy, and anesthesia-related pulmonary complications. Although controversy exists regarding the use of neuraxial anesthesia in these patients, multiple case reports exist in the literature describing its use with good efficacy and without neurological sequelae. We present a case an adult with SMA undergoing abdominal surgery in whom epidural anesthesia was performed for postoperative pain control.
Spinal muscular atrophy or SMA is a rare autosomal recessive neuromuscular disease that presents in a variety of forms, the majority of which cause diffuse symmetric proximal muscle weakness, hypotonia, absent or decreased deep tendon reflexes, and atrophy that is greater in the lower limbs than the upper limbs1. SMA type III, or Kugelberg-Welander disease, is the chronic juvenile form that usually presents after 18 months of age and occurs with a frequency of approximately 1 in 24,000 births. Its mortality and morbidity rates are inversely correlated with the age at onset. Medical complications associated with the SMAs that can present challenges to the anesthesia provider include pulmonary infections, spinal deformities (eg, scoliosis, kyphosis), joint contractures, and respiratory failure. Challenges specific to neuraxial anesthesia include abnormal spinal anatomy which can result in difficult epidural placement and unpredictable local anesthetic spread. A titratable epidural or continuous spinal infusion may be the most effective way to achieve an adequate block height and optimize pain relief in the postoperative period. Although there are no randomized controlled trials describing the efficacy or safety of neuraxial anesthesia in this patient population, there are multiple case reports describing its successful use without complication2. We present a case of anesthetic management of a patient with SMA type III for laparoscopic revision of sigmoid colostomy using epidural anesthesia for postoperative pain control.
This was a 59 year-old wheelchair dependent man with past medical history of hypertension and SMA type III who presented for a laparoscopic revision of his dysfunctioning sigmoid colostomy. He had not ambulated in greater than twenty years but denied any difficulty in swallowing or breathing. He had 3-4 / 5 strength in both upper extremities and performed most ADL “transfers” using a modified Hoyer lift.
Preoperatively, ASA monitors were attached and the patent was given 1.5 mg of midazolam and 75 mcg of fentanyl in divided dosing before being moved into the sitting position. Using sterile drape and technique, the initial attempt of locating the epidural space at the T9-10 level via a midline approach was unsuccessful. The next attempt by the same provider using a right paramedian approach was also unsuccessful. On the third attempt, the epidural space was identified by loss of resistance technique using an 18 G Tuohy insertion needle and a left paramedian approach. After a test dose injection of 3 ml 1.5% lidocaine containing 1:200,000 epinephrine, no increase in heart rate or intrathecal anesthesia symptoms were detected. Intraoperative anesthetic management included induction with propofol and 20 mg rocuronium to facilitate endotracheal intubation, maintenance with sevoflurane at approximately 1 MAC, and minimal intraoperative opioids for pain control. No additional neuromuscular blocker was given and muscle relaxation was monitored regularly using train-of-four technique. At the end of the case muscle relaxant was antagonized with 2.5 mg neostigmine (and 0.4 mg glycopyrrolate) and the volatile anesthetic stopped. The patient woke up quickly and was able to perform sustained head-lift at which time he was extubated and transferred to the postanesthesia care area (PACU).
Postoperatively, there was no evidence of residual or prolonged muscle weakness, respiratory compromise, or complications from neuraxial anesthesia. The epidural was bolused postoperatively with 4 ml of 2% lidocaine and 75 mcg of fentanyl in the PACU. The patient’s 9/10 pain was decreased to 4/10 and an anesthetic sensory level of T5-L3 was achieved bilaterally. An infusion of 0.1% ropivacaine with 10 mcg/mL of hydromorphone was initiated at 6 ml/hr and titrated to patient comfort. Because of worsening pain scores on postoperative day 2, the ropivacaine concentration was increased to 0.2% to successfully achieve a denser block. Adequate sensory level blockade was achieved and maintained providing great pain control throughout the acute postoperative period. On postoperative day 3, the patient began tolerating oral medications and a general diet. Trial of epidural stoppage revealed continued great pain control using oral opioids and the epidural was subsequently removed. The patient recovered smoothly without complication and was discharged home from the hospital on postoperative day four.
Several elements of this disease can present challenges to anesthetic management including hypersensitivity to muscle relaxants, elevated risk of postoperative respiratory complications, and altered spinal anatomy resulting in difficult neuraxial anesthetic placement with unpredictable local anesthetic spread3,4. We present a patient with SMA type III in whom postoperative pain was successfully controlled using epidural anesthesia without neurological complication or sequelae. We were able to overcome these challenges by using minimal neuromuscular blocker, vigilant train-of-four monitoring, and a titratable form of neuraxial anesthesia. This allowed us avoid the sedative effects of postoperative opioids and enabled the patient to pursue aggressive respiratory oximetry to prevent postoperative pulmonary complications.