Cauda equina syndrome (CES) is a rare ailment during early pregnancy. Emergency lumbar discectomy for CES accounts for <2% of women undergoing lumbar disk surgery.1 Balanced general anesthesia is the preferred anesthetic technique for lumbar discectomy, although use of general anesthesia in early pregnancy is highly controversial. Spinal anesthesia has been advocated to avoid adverse effects of general anesthetic agents on the fetus.2 However, hypotension after spinal anesthesia is detrimental for fetal circulation. Therefore, a search for the ideal anesthetic technique in early pregnancy is still continuing. This case report highlights the usefulness of ultrasound-guided bilateral paravertebral block for lumbar microdiscectomy in early pregnancy. We modified the procedure to ensure that the dorsal rami nerves are covered. Written informed consent was obtained from the patient.
A 31-year-old woman with multiple (triplets) pregnancy through in vitro fertilization and at 9 weeks’ gestation was admitted with complaint of numbness in buttocks and both thighs. She had urinary retention for more than 12 hours. Examination of other systems was unremarkable. Routine blood and biochemical examinations were within normal limits. She had history of disk prolapse about 15 years ago, which was conservatively managed. She was diagnosed with CES and was advised to have an urgent magnetic resonance imaging. The magnetic resonance imaging revealed a diffuse disk herniation with caudal migration at fifth lumbar vertebra–first sacral vertebra level causing marked extradural compression. Fetal Doppler examination was done before the procedure to ensure fetal well-being. She was posted for emergency microdiscectomy. The type of anesthesia to be administered was debated, as the patient was in the first trimester of pregnancy.
Various anesthetic techniques (ie, general anesthesia, spinal anesthesia, and paravertebral block) and their possible side effects on early pregnancy were discussed with the patient and the surgeon. After thorough deliberation, the patient agreed to undergo microdiscectomy under bilateral paravertebral block. Written informed consent was obtained for the procedure. The patient was positioned prone with a pillow beneath the chest and face and on each side of the pelvis to minimize pressure on the lower abdomen. A towel roll was placed beneath the ankles, and a gel pad was placed beneath the knees. The patient was allowed to keep her arms in whichever position she felt comfortable, and her elbows were padded. After cleaning and draping, a low-frequency (2–5 MHz) curved array ultrasound transducer was positioned approximately 3–4 cm lateral and parallel to the lumbar spine, with orientation marker directed cranially so as to produce a longitudinal scan of the lumbar paravertebral region. The transducer was then moved caudally while still maintaining the same orientation until the sacrum and the fifth lumbar vertebra transverse process were visible. The probe was moved medially to identify the facet joint. Then, the probe was retracted by a few millimeters laterally, and the needle was inserted in the long axis (in-plane) of the ultrasound transducer from the cranial end and advanced through the space between the transverse processes. The tip was directed toward the first sacral vertebra transverse process, and after crossing the intertransversarius muscle (Figure 1A), 5 mL of 0.5% bupivacaine was injected. The needle was redirected to penetrate the posterior belly of the psoas major muscle to reach the paravertebral plexus (Figure 1B), and 10 mL of 0.5% bupivacaine was then deposited. The procedure was repeated on the contralateral side. Continuous pulse oximetry, noninvasive blood pressure monitoring, and electrocardiography were performed intraoperatively. Intravenous fentanyl (50 µg) was administered to alleviate discomfort during traction of the nerve root. Vitals remained stable throughout the procedure. Radiation exposure was minimized by restricting imaging to 2 occasions only.
The surgery lasted for approximately 45 minutes. One liter of Ringer’s lactate solution was transfused. The procedure was uneventful, and the patient remained comfortable throughout the surgery. Fetal Doppler was repeated after the procedure, and the results were unremarkable.
Patient’s bladder function recovered over the next 2 days, and the numbness over the saddle area also subsided. The patient was discharged on the third postoperative day without any residual neurological deficit. The pregnancy progressed uneventfully.
Each year approximately 2% of pregnant women undergo surgery for nonobstetric conditions.3 Surgery involving the spine during pregnancy has its own challenges, such as positioning, effect of radiation, and effect of anesthesia on the fetus. The ultimate goals are to preserve maternal safety, maintain the pregnant state, and achieve the best possible fetal outcome.
It has been recommended that elective surgery should be deferred until the second trimester to decrease the risk of teratogenicity and miscarriage.4,5 An overall miscarriage rate after surgery of 5.8% has been reported and was found to increase to 10.5% in the first trimester.5 Furthermore, first-trimester anesthesia increases the risk of low birth weight.6
Both general anesthesia and spinal anesthesia have been used for spine surgery. General anesthesia has the advantages of patient comfort, ability to perform prolonged procedures, and better control of airway. Spinal anesthesia has the least placental drug transfer. However, sympathetic blockade culminating in maternal hypotension is a major downside.4 To circumvent the above-mentioned anesthetic concerns, lumbar paravertebral block was used. With this regional technique, adequate analgesia without significant hemodynamic changes is provided. Moreover, potentially teratogenic drugs are avoided and lesser incidence of nausea and vomiting is reported as compared to general anesthesia.7 In addition, postoperative analgesia is superior. To the best of our knowledge, this is the first case report of bilateral paravertebral block for microdiscectomy in early pregnancy.
We modified the technique to ensure the block of the dorsal rami nerves at their exit because they may be spared in the standard paravertebral block (Figure 2). We used an ultrasound-guided technique to better visualize the nerves and surrounding structures. The deposition and spread of local anesthetic can be observed, thus reducing the need for larger doses of local anesthetic.
In this case report, we propose that a lumbar paravertebral block is a safe alternative anesthetic for limited lumbar spine surgery in early pregnancy.
Name: Charoo Negi, MD.
Contribution: This author helped conceive the case report, contribute to the intellectual content, and draft the manuscript.
Name: Hari Hara Dash, MD.
Contribution: This author helped conceive the case report, contribute to the intellectual content, and revise the manuscript.
Name: Balkar Singh, MD.
Contribution: This author helped contribute to the intellectual content and care for the patient.
This manuscript was handled by: BobbieJean Sweitzer, MD, FACP.
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