Concordant pressure paresthesia during interlaminar lumbar epidural steroid injections correlates with pain relief in patients with unilateral radicular pain.

BACKGROUND: Transforaminal and interlaminar epidural steroid injections are commonly used interventional pain management procedures in the treatment of radicular low back pain. Even though several studies have shown that transforaminal injections provide enhanced short-term outcomes in patients with radicular and low back pain, they have also been associated with a higher incidence of unintentional intravascular injection and often dire consequences than have interlaminar injections. OBJECTIVES: We compared 2 different approaches, midline and lateral parasagittal, of lumbar interlaminar epidural steroid injection (LESI) in patients with unilateral lumbosacral radiculopathic pain. We also tested the role of concordant pressure paresthesia occurring during LESI as a prognostic factor in determining the efficacy of LESI. STUDY DESIGN: Prospective, randomized, blinded study. SETTING: Pain management center, part of a teaching-community hospital in a major metropolitan US city. METHODS: After Institutional Review Board approval, 106 patients undergoing LESI for radicular low back pain were randomly assigned to one of 2 groups (53 patients each) based on approach: midline interlaminar (MIL) and lateral parasagittal interlaminar (PIL). Patients were asked to grade any pressure paresthesia as occurring ipsilaterally or contralaterally to their "usual and customary pain," or in a distribution atypical of their daily pain. Other variables such as: the Oswestry Disability Index questionnaire, pain scores at rest and during movement, use of pain medications, etc. were recorded 20 minutes before the procedure, and on days 1, 7, 14, 21, 28, 60, 120, 180 and 365 after the injection. RESULTS: Results of this study showed statistically and clinically significant pain relief in patients undergoing LESI by both the MIL and PIL approaches. Patients receiving LESI using the lateral parasagittal approach had statistically and clinically longer pain relief then patients receiving LESI via a midline approach. They also had slightly better quality of life scores and improvement in everyday functionality; they also used less pain medications than patients receiving LESI using a midline approach. Furthermore, patients in the PIL group described significantly higher rates of concordant moderate-to-severe pressure paresthesia in the distributions of their "usual and customary pain" compared to the MIL group. In addition, patients who had concordant pressure paresthesia and no discordant pressure paresthesia (i.e., "opposite side or atypical") during interventional treatment had better and longer pain relief after LESI. Two patients from each group required discectomy surgery in the one-year observation period. LIMITATIONS: The major limitation of this study is that we did not include a transforaminal epidural steroid injection group, since that is one of the approaches still commonly used in contemporary pain practices for the treatment of low back pain with unilateral radicular pain. CONCLUSIONS: This study showed that the lateral parasagittal interlaminar approach was more effective than the midline interlaminar approach in targeting low back pain with unilateral radicular pain secondary to degenerative lumbar disc disease. It also showed that pressure paresthesia occurring ipsilaterally during an LESI correlates with pain relief and may therefore be used as a prognostic factor.

Magnetic resonance imaging is essential prior to spinal subarachnoid blockade for parturients with a history of brain tumor resection undergoing cesarean section.

BACKGROUND: Primary brain tumors are usually treated by surgical removal with the goal of complete resection within the constraints of preservation of neurological function. However, gross total resection may not mean complete tumor removal, and ongoing compression from a mass effect can lead to serious sequelae. Spinal subarachnoid blockade is contraindicated in patients with brain tumors or space occupying lesions. CASE DESCRIPTION: A 32-year-old full term parturient presented to Labor and Delivery for semi-urgent repeat cesarean section. Three months ago, she underwent resection of a benign brain tumor and recovered with no new neurological deficits. The neurosurgeon was consulted by the anesthesia team and stated that the tumor was completely extirpated. Since there was no postoperative magnetic resonance imaging (MRI) and the patient still had some neurological deficits, the anesthesia team decided to proceed with a general anesthetic using a rapid sequence induction and intubation. Mild hyperventilation to maintain an end-tidal CO(2) of 30 mmHg was selected and conservative fluid management was maintained. Postcesarean MRI revealed residual tumor compressing the brain stem and a loculated cyst. If a spinal subarachnoid blockade technique had been selected, the risk of uncal herniation, based on the postoperative MRI findings, may have been realized. CONCLUSIONS: The present case demonstrates the necessity of a comprehensive and thorough review prior to selecting the anesthetic approach to mange the patients with a history of brain tumor resection. Postoperative MR imaging should be performed to evaluate the extent of tumor resection and possible existence of residual tumor.