Limb-girdle muscular dystrophy with obesity for elective cesarean section: Anesthetic management and brief review of the literature.

Limb-girdle muscular dystrophy (LGMD) is an autosomal recessive disorder in which the pelvic or shoulder girdle musculature is predominantly or primarily involved. We report the management of a 27-year-old primigravida with LGMD associated with obesity posted for elective cesarean section. She was successfully managed with epidural anesthesia assisted with noninvasive positive pressure ventilation. She had an uncomplicated intra- and post-operative course.

INTRODUCTION

Limb-girdle muscular dystrophy (LGMD) constitutes a group of genetically determined, progressive disorders of muscle in which the pelvic or shoulder girdle musculature is predominantly or primarily involved.[1] It is an extremely rare disorder with the incidence quoted as <1/100,000.[2] It may be inherited in an autosomal recessive (AR) (90%) or dominant (10%) fashion.[3] In their most severe form, they may be associated with respiratory compromise that can be exacerbated by the physiological demands of pregnancy.[4]

CASE REPORT

This case describes the anesthetic management of a 27-year-old primigravida at 38 weeks +2 days period of gestation with a history of LGMD, she was posted for elective lower segment caesarean section at our hospital, Pondicherry Institute of Medical Sciences. She was 153 cm tall and weighed 105 kg (body mass index - 44.85 kg/m2).

She was diagnosed with LGMD in 2007. Her recent muscle biopsy revealed muscle tissue with effaced architecture, infiltration by adipose tissue and moderate endomysial fibrosis. Myofibers were round and varying in diameter with evidence of internal nuclei, myophagocytosis, splitting and few angulated atrophic fibers giving an impression of muscular dystrophy with secondary neurogenic features.

Her symptoms predominantly affected the lower limbs and at the time of admission she had difficulty in getting up from sitting position. She was never wheelchair bound and had no cranio-bulbar symptoms. Preoperative evaluation by neurologist showed significant proximal muscle weakness in all the limbs which was more in upper limbs. The power was 3/5 in upper limbs and 4/5 in the lower limbs with depressed reflexes. In view of these findings, she was advised to undergo elective cesarean section.

Preoperative investigations revealed hemoglobin of 11.2 g%, normal thyroid profile, and normal renal function and coagulation tests. Pulmonary function tests revealed forced expiratory volume in 1 s (FEV1) of 64% and forced vital capacity (FVC) of 67%, FEV1/FVC >90%, suggestive of a restrictive pattern secondary to muscular dystrophy. She was advised breathing exercises and chest physiotherapy. Echocardiography showed good left ventricular functions, no evidence of cardiomyopathy or pulmonary hypertension.

She was planned for epidural anesthesia. Procedure was explained to her in detail the previous day and was advised to stay nil per oral from 12 at midnight. As a part of aspiration prophylaxis tablet ranitidine 150 mg at night and 7.00 am next morning and a night dose of tablet metoclopramide 10 mg was advised. With the anesthetic machine flushed and C mac video laryngoscope, difficult intubation cart, and percutaneous tracheostomy set in close proximity, the patient was brought to the operating room. Monitors were attached (electrocardiography, noninvasive blood pressure and SpO2). Her heart rate was 92/min, blood pressure was 140/96 mm of Hg and pulse-oximetry read 98%. 16-gauge intravenous access was secured on the left hand under aseptic precautions; right radial artery was cannulated with 20-gauge cannula. Arterial blood gas analysis was done prior to starting anesthesia procedure which showed normal result. Patient was preloaded with Ringer's lactate (RL) (5 ml/kg). With the patient in sitting position, under the strict aseptic precaution, 16-gauge Tuohy's needle was used to identify the epidural space at L2-L3 space using loss of resistance technique with air. Epidural space was identified 8 cm from skin and catheter was fixed at 14 cm from skin level. After negative aspiration of blood/cerebrospinal fluid 3 ml of 2% lignocaine with adrenaline was given as test dose. After confirming no significant changes in heart rate and blood pressure, 12 ml of 0.5% bupivacaine was injected in slow incremental doses. Noninvasive positive pressure ventilation (NPPV) was started prophylactically with pressure support of 15 mm of Hg and positive end-expiratory pressure of 5 mm of Hg with FiO2 of 40%. T6 level was achieved within 15 min of administration of the drug. Patient remained hemodynamically stable throughout the surgery. A healthy female child was delivered with APGAR of 8/10 at 1 min and 10/10 at 5 min and was handed over to the attending pediatrician. A total of 1.5 L of RL was administered, and U/O of 500 ml was documented. At the end of the surgery, slowly her pressure support was reduced and she was weaned off from positive pressure ventilation and then she was shifted to surgical intensive care unit for an overnight stay. Patient was put on thromboprophylaxis with enoxaparin at a dose of 40 mg/day. Epidural infusion of 0.0625% bupivacaine along with fentanyl 2 mcg/ml was started at 6 ml/h. Patient had stable hemodynamics, adequate urine output, and good pain relief throughout. Patient was shifted to the ward next day. After 36 h of surgery, the epidural catheter was removed timing it to 12 h after previous dose of enoxaparin. Subsequent dose of enoxaparin was resumed after 12 h of catheter removal.

DISCUSSION

Limb-girdle muscular dystrophy is an AR/dominant muscular class of disorders in which the muscle fibers slowly break down and are replaced by connective tissue and fat. Muscle degeneration leads to muscle weakness and atrophy. The name of the condition refers to the muscles affected, mainly those around the pelvic and shoulder girdles, also known as the limb-girdles.[5] The clinical course of this group of muscular dystrophies is variable. Onset may be from the first to the fourth decade of life with severe forms of the disease beginning in early life and late-onset disease running a milder course. Very few cases of anesthetic management in LGMD are reported in the literature. Pubmed search revealed three cases in pregnant women.[267] Marked progression or exacerbation of symptoms is reported in women with LGMD during pregnancy. Obstetric complications are known to occur in these women especially if they develop severe pelvic girdle muscle weakness and respiratory insufficiency.[4] Multi-disciplinary approach is essential in planning the delivery in these cases. Hence, a team of obstetricians, anesthesiologists, pulmonologists, and neurologists in our hospital decided to electively perform the caesarian section to prevent obstetric and pulmonary complications.

In view of a rarity of the disorder, there are no randomized controlled trials comparing general anesthesia and regional anesthesia in these patients. To avoid the deleterious effect of subarachnoid anesthesia and general anesthesia, segmental epidural as esthetic technique was preferred in our case. In the three reported cases in pregnant women, one case was managed with spinal anesthesia, another with combined spinal-epidural anesthesia and yet another with epidural anesthesia as in our case.[267] Compared to all available techniques, segmental epidural has got the least effect on respiratory and cardiovascular system. Evidence exists in literature that epidural anesthesia using 0.5% plain bupivacaine in healthy full term parturient women undergoing elective cesarean section was not associated with any significant change in FVC, FEV1, peak inspiratory flow rate, peak expiratory flow rate, peak inspiratory pressure or peak expiratory pressure at T10 and T4 sensory levels, when compared with baseline preblock values.[8] Evidence also exists about the deleterious effect of spinal anesthesia on the respiratory system in pregnant women where in Conn et al.[9] demonstrated that spinal anesthesia caused a significant reduction in FEV1, FVC, and PEFR from prespinal levels with up to a 19%, 17%, and 35% reduction in FEV1 FVC, and PEFR respectively. However, in patients with muscular dystrophy even epidural block might affect the respiratory function more so in the supine position. Hence, we decided to provide NPPV intra-operatively. Of the three reported cases, two were assisted with NPPV, whereas one case was managed with only epidural without NPPV. The last patient had respiratory deterioration indicated by raising PaCO2 in the postoperative period, which settled with chest physiotherapy and incentive spirometry by 3 days. The authors have mentioned about the use of intra-operative blood gas analysis in these types of patients for early diagnosis of respiratory compromise.

Regional anesthesia is contraindicated in those patients who are unable to tolerate lying supine despite respiratory support or those with bulbar muscle involvement putting them at risk of aspiration. Fortunately, this was not the case in our patient, but if the need arose we were ready to induce general anesthesia with rapid sequence induction using thiopentone and atracurium, maintenance with sevoflurane and lumbar epidural catheter for postoperative pain relief.[2] It is advised that the difficult intubation cart should be ready as most of the LGMD patients are obese and additional monitoring like neuromuscular temperature and end tidal CO2 monitoring should be available during the conduct of general anesthesia. Succinylcholine produces exaggerated contracture, and its use should be avoided. The myotonic responses to succinylcholine are so severe that ventilation and tracheal intubation are difficult.[1011] Early extubation and NPPV are recommended to prevent postoperative pulmonary compilations.[210]

In summary, the management of pregnant women with AR-LGMD depends on the severity of the disease but the most severe cases are best-managed by a multi-disciplinary team including obstetricians, neurologists, anesthesiologists, and respiratory and critical care physicians. This case highlights the fact that regional anesthesia, especially segmental epidural can be safely used to provide anesthesia for cesarean section in patients with muscular dystrophy. NPPV can be used to attenuate any exacerbation of respiratory symptoms associated with neuraxial anesthesia and it also avoids intubation; hence should be considered as a part of the perioperative management in these patients.