Labor analgesia for the parturient with scoliosis & previous back surgery Samina Ismail Associate Professor Aga Khan University Karachi, Pakistan

Road Map What is Scoliosis? Challenges faced during provision of labour analgesia. Is neuraxial technique possible for these patients? What are other options of pain relief. Labour analgesia for patents with neural tube defect

What is “Scoliosis”? Scoliosis is defined as a lateral curvature of the spine and is present in 2% of general population (1) with the prevalence in women twice than in men

Thoracic Scoliosis Lumbar Scoliosis

Severity of Scoliosis Severity of the scoliosis is defined by “Cobb angle”. More than 400 angle is considered severe with associated cardiac and pulmonary dysfunction (3). Many of these patients undergo surgery (e.g. Harrington rod insertion) to correct spinal curvature

Curve of >400 require surgical correction

Explanation of risk & benefits: These patients requiring obstetric anaesthesia services should be referred early in the preoperative anesthesia clinic for: When refused by patients or technically impossible. Intravenous PCIA is the “next –best” choice- fentanyl/ remifentanil are commonly used drugs. Fentanyl: Loading dose 50-100mcg Bolus 20-40 mcg Lock out time 5-10 minutes Remifentanil: Basal infusion 0-0.05 mcg/kg/min Bolus 25-50 mcg Lock out time 5 minutes Evron S, Ezri T. Options for systemic labour analgesia. Curr Opin Anaesthesiol 2007; 20 :181 Evaluation of any associated cardiopulmonary and musculoskeletal disease. Evaluation of operative and radiographic reports in assessing the location and extend of vertebral anomalies. Discussion with the patient and family of different options of labor analgesia. Explanation of risk and benefits of labor epidurals. Counseling for the possible failures of techniques. Explanation of risk & benefits: Failure of technique. Inadequate analgesia Increase likelihood of dural puncture Less potential for successfully treating PDPH High block Risk of infection in case of previous surgery May have severe cardiopulmonary dysfunction Increase chances in patients with neuromuscular disease Unlike if correction is done during teenage years.

Challenges Faced!! In providing neuraxial analgesia for patients with or without corrective surgery are: inability to identify the epidural space multiple attempts before catheter insertion patchy analgesia accidental dural puncture

The anatomic anomalies leading to these challenges are as follow: Distortion or absence of spinous processes, which is the key landmark of placement of neuraxial anesthesia; therefore palpation is not always the best method for the identification of space.

In uncorrected scoliosis, there is deviation of the midline of the epidural space towards the convex aspect of the scoliosis relative to the spinous process. In the uncorrected patient the needle should be oriented towards the convexity of the curve where the interlaminar spaces are generally larger

Spinal surgery involves decortication of vertebrae and removal of spinous process along the extent of the curve Scar tissue in post surgical patient and bone grafts can hinder the entry of neuraxial needles into the desired space Patient with Harrington rod are unable to flex their spine. Postoperative adhesion or obliteration of the epidural space can interfere with local anesthetic spread and increase chances of inadvertent dural puncture and inadequate anesthesia

Is neuraxial technique possible in these patients? Despite these difficulties, successful spinal and epidural have been reported in parturient with corrected and uncorrected scoliosis.

Labor pain relief in patients with previous spinal instrumentation First two reports in 1985 Labor pain relief in patients with previous spinal instrumentation Feldstein G, Ramanathan S. Obstetrical lumbar epidural anesthesia in patients with previous posterior spinal fusion for khyphoscolisis. Anes Analg. 1985. Hubbert CH. Epidural anaesthesia in patients with spinal fusion. Anes Analg. 1985.

Successful epidural analgesia is reported in the range of 42-94%. Can J Anesth 1989 Reg Anesth 1990 Anesth Analg 2009

Literature Review 22 articles reported 117 neuraxial techniques in parturient. Ko J Y, Leffert R L. Clinical implication of neuraxial anaesthesia in parturient with scoliosis. Anesth Analg 2009

n=24 n=93 n=117

Outcomes of Neuraxial Procedures 24 79% 19 93 69% 64 2 Persistent back pain after epidural placement of unknown etiology

Trouble shooting in case of inability or ineffective functioning of labor epidural:

Ultrasonography may be helpful tool in defining the relevant anatomy at the time of initiation of neuraxial anesthesia Normal Spine Scoliotic Spine Can J Anaesth 2005;52:717-20.

In the uncorrected patient the needle should be oriented towards the convexity of the curve where the interlaminar spaces are generally larger

In case of unilateral block due to rotation of the spine : Patient can be paced in the lateral position with the less blocked side in the dependent position.

In case of patchy block: Large volume / low concentration LA may overcome the problem. Placement of additional epidural catheter at the level of the unblocked dermatome has been described .

Spinal Anaesthesia The absence of scarring within the intrathecal space ensures unhindered spread of local anesthetic in post spinal surgery patient. The dose of spinal anesthetic should be reduced to half, if is used after a failed epidural Dadarkar P, Philips J, Werdner C, Perz B, Slaymarker E, TabaczewaskaL, Wiley J, Sharma S. Spinal Anaesthesia for cesarean section following inadequate labor analgesia: a retrospective analysis. Int J Obstet Anesth 2004; 13 (4):239-43.

Labor analgesia for spina bifida.

Spina bifida occulta Meningocele Spina bifida cystica is the more severe form and is defined as failed closure of neural arch with herniation of meninges (meningocele), the meninges and neural elements (meningomyelocele Spina bifida occulta What is Spina Bifida? Type of neural tube defect (incidence 1/1000). Group of condition categorized into: Spina bifida occulta. Spina bifida cystica Spina bifida oculta arises when the two halves of the vertebral arch fail to fuse in the midline. The spinal cord and nerve roots are normal. There is no external lesion. Spina bifida cystica Meningocele Meningomyeloele

Meningomyeloele

Most severe form of Spina Bifida Cystica: Myeloschisis Failure of neural folds to fuse myeloschisis

Preoperative Anesthesia Evaluation Medical history : Coexisting defects in the genitourinary, respiratory, musculoskeletal and cardiovascular systems. Degree of neurological impairment must be precisely defined by imaging studies : plain radiographs computerized tomography ideally before magnetic resonance pregnancy   delineate the exact location of the spinal defects, its extent, and will provide some guidance for the placement of epidural for labor. Kuczkowski KM. Labor Analgesia for pregnant women with spina bifida: What does an obstetrician needs to know? Arch Gynecol Obstet 2007 ;275: 53-66.

How to provide labour analgesia? No specific guidelines for administration of labour analgesia. Regional techniques have been reported but with limitations and complications.

Tidmarsh, May AE Epidural anaesthesia and nural tube defects Tidmarsh, May AE Epidural anaesthesia and nural tube defects. Int J Obstet Anaesth 1998; 7:111-14. conducted retrospective chart reviews of the anesthetic management during labor of 16 patients. The authors concluded that the conduct of epidural analgesia in patients can be technically difficult and results often unpredictable (e.g., excessive cranial/ poor perineal spread of local anesthetic and /or asymmetric block

International Journal of Obstetric Anesthesia Volume 18, Issue 3, July 2009, Pages 258-261 Adjunct to unsatisfactory fentanyl IVPCA is reported in a 31-year-old parturient with spina bifida occulta and a tethered spinal cord reaching L5-S1. Dexmedetomidine significantly improved the analgesic quality; increased sedation was observed, but the patient was easily rousable to verbal stimuli. No episodes of maternal hypotension or bradycardia, or fetal heart rate irregularities occurred. Cesarean delivery was required for prolonged first stage of labor and presumed chorioamnionitis; it was conducted under general anesthesia during which the dexmedetomidine infusion was continued. A healthy baby boy was delivered with normal Apgar scores and no discernible neurobehavioral or other deficits.

Conclusion: Providing labor analgesia for these patients, pose lots of challenges to the obstetric anesthetists. Every patient needs to be individualized. Assessment in the preoperative clinic for associated medical problems and extend of lesion. Understanding the anatomic anomalies in these patients helps in the institution of neuraxial anesthesia. Since regional technique is the ideal method of labor analgesia, these patients should be given a trail after proper planning .

Anatomical deformity should not be hindrance for the provision of pain relief for laboring women

In January 19, 1847 first anaesthesia using diethyl ether was used by Simpson to anaesthetize a woman with deformed pelvis.

Remember! “The delivery of an infant into the arms of a conscious and pain free mother is one of the most exciting and rewarding moment in medicine” Moir DD - 1979

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