CASE REPORT J Neurosurg Spine 26:430–434, 2017 Congenital hypoplasia of the lumbar pedicle with spondylolisthesis: report of 2 cases Chang-Sheng Hsieh, MD,1 Sang-Ho Lee, MD, PhD,2 Hyung Chang Lee, MD,3 Hyeong-Seok Oh, MD,4 Byeong-Wook Hwang, MD, PhD,4 Sang-Joon Park, MD,4 and Jian-Han Chen, MD5,6 Departments of 1Orthopaedics and 4Neurosurgery, Wooridul Spine Hospital, Busan; 2Department of Neurosurgery, Wooridul Spine Hospital, Seoul; 3Department of Cardiovascular Surgery, Wooridul Spine Hospital, Gimpo Airport, Seoul, Korea; 5Department of General Surgery, Buddhist Dalin Tzu Chi Hospital, Chia-Yi; and 6School of Medicine, Tzu Chi University, Hualien, Taiwan Congenital hypoplasia of the spinal pedicle is a rare condition. Previously reported cases were treated conservatively or with posterior instrumented fusion. However, the absence or hypoplasia of the lumbar pedicle may increase the difficulty of pedicle screw fixation and fusion. Herein, the authors describe 2 cases of rare adult congenital hypoplasia of the right lumbar pedicles associated with spondylolisthesis. The patients underwent anterior lumbar interbody fusion with a stand-alone cage as well as percutaneous pedicle screw fixation. This method was used to avoid the difficulties associ- ated with pedicle screw fixation and to attain solid fusion. Both patients achieved satisfactory outcomes after a minimum of 2 years of follow-up. This method may be an alternative for patients with congenital hypoplasia of the lumbar spinal pedicle. https://thejns.org/doi/abs/10.3171/2016.8.SPINE151137 KEY WORDS congenital hypoplasia; lumbar pedicle; spondylolisthesis ONGENITAL hypoplasia of the spinal pedicle is an Case Reports uncommon anomaly. When it occurs, it mostly in- Case 1 volves the cervical or thoracic spine; the absence of Ca lumbar or sacral pedicle is rare.3,5,6,9,20,21,26 The majority History and Examination of cases with an absence or hypoplasia of the lumbosacral A 63-year-old man presented with chronic low-back pedicles are asymptomatic, and they are usually discov- pain and severe radicular pain in the right lower extrem- ered incidentally. Low-back pain is the most frequently re- ity. Prior conservative treatment with physical therapy ported symptom.6 The rarer cases present with intractable and medication was unsuccessful. Physical examination low-back pain or neurological impairment requiring sur- revealed decreased muscle power in bilateral big toe dor- gery. Most patients are treated with posterior instrument- siflexion (Grade 4/5 on the Medical Research Council ed fusion; however, hypoplasia of the lumbar pedicle may [MRC] motor scale).19 All modalities of sensation were increase the difficulties associated with the pedicle screw intact. To assess low-back and radicular pain, we used a fixation and fusion. Herein, we present 2 cases of unilat- visual analog scale (VAS) for pain (0 indicated no pain; eral hypoplasia of the pedicles in the lumbar spine with 10 indicated the worst pain). Preoperative VAS scores for concurrent spondylolisthesis, leading to low-back pain and low-back and leg pain were 6 and 8, respectively. The deep radicular pain of the lower extremities. The surgical strat- tendon reflexes were 2+ bilaterally. The standing weight- egy in these cases consisted of anterior lumbar interbody bearing radiographs of the lumbar spine revealed hypopla- fusion (ALIF), followed by percutaneous pedicle screw sia of the right L-4 pedicle and Meyerding Grade I spon- fixation (PPF) without posterior decompression. dylolisthesis at the L4–5 level (Fig. 1).13 A CT scan of the ABBREVIATIONS ALIF = anterior lumbar interbody fusion; MRC = Medical Research Council; PPF = percutaneous pedicle screw fixation; VAS = visual analog scale. SUBMITTED January 10, 2016. ACCEPTED August 3, 2016. INCLUDE WHEN CITING Published online January 6, 2017; DOI: 10.3171/2016.8.SPINE151137. 430 J Neurosurg Spine Volume 26 • April 2017 ©AANS, 2017 Unauthenticated | Downloaded 09/24/21 03:04 PM UTC Congenital hypoplasia of lumbar pedicle with spondylolisthesis FIG. 1. Case 1. Left: Anteroposterior radiograph of the lumbosacral spine reveals hypoplasia of the right L-4 lumbar pedicle (arrow- FIG. 3. Case 1. Six-month postoperative radiographs. Left: Anteropos- head). Right: Lateral view. A neutral weight-bearing radiograph shows terior view. Right: Lateral view. The patient was treated with ALIF using Meyerding Grade I spondylolisthesis at the L4–5 level. a SynFix cage and left-sided pedicle screw fixation. lumbar spine revealed hypoplasia of the right L-4 pedicles in bilateral big toe dorsiflexion (MRC Grade 5/5). The dy- and articulating processes (Fig. 2 left). On the left side, namic radiograph of the lumbosacral spine revealed bony there was degeneration of the L4–5 facet joints, with frac- fusion with no evidence of pseudarthrosis at the 2-year ture of the pars interarticularis (Fig. 2 right). follow-up (Fig. 3). Treatment Case 2 We performed an ALIF with the SynFix system (Syn- History and Examination thes Spine Inc.) and screws. The percutaneous pedicle An 84-year-old man presented with chronic low-back screws were fixed via the paramedian approach on the left pain and radicular pain that radiated to the bilateral lower side of L4–5. Posterior decompression was not performed extremities. Preoperative VAS scores for the low-back during surgery. and radicular pain were both 8. Physical examination re- vealed decreased muscle power in both right and left big Postoperative Course toe dorsiflexion (MRC Grades 2/5 and 4/5, respectively). The patient’s postoperative VAS scores for low-back There was also a reduction in the power of bilateral ankle and radicular pain reduced to 1 and 0, respectively. Physi- dorsiflexion (MRC Grade 4/5 bilaterally). All modalities cal examination revealed normalization of muscle power of sensation were intact. The deep tendon reflexes were 2+ bilaterally. The standing weight-bearing radiographs of the lumbar spine revealed hypoplasia of the right L-5 pedicle and Meyerding Grade I spondylolisthesis at the L4–S1 level (Fig. 4). A CT scan of the lumbar spine dem- onstrated hypoplasia of the right L-5 pedicle, fracture of the L-5 pedicle root, and L4–5 foraminal stenosis (Fig. 5). Treatment The patient’s low-back and radicular pain did not im- prove with conservative treatment; therefore, we per- formed an ALIF using the SynFix system with screws at the L4–5 and L5–S1 levels. Additionally, we used PPF via the paramedian approach bilaterally at the L-4 and S-1 levels. Posterior decompression was not performed during surgery. The pedicle screws were augmented with poly- methylmethacrylate (PMMA) cement due to severe osteo- FIG. 2. Case 1. Axial and sagittal CT (without contrast) scans of the porosis (bone mineral density of the femoral neck -3.3). lumbosacral junction. Left: An axial reconstruction of spinal CT scans demonstrates congenitally hypoplastic right L-4 pedicles and articulating Postoperative Course processes (arrowhead). Right: The severely degenerated hyperplastic contralateral L4–5 facet joints including the fracture of the pars interar- The patient’s postoperative VAS scores for low-back ticularis (arrowhead). and radicular pain reduced to 1 and 0, respectively. Physi- J Neurosurg Spine Volume 26 • April 2017 431 Unauthenticated | Downloaded 09/24/21 03:04 PM UTC C. S. Hsieh et al. FIG. 5. Case 2. Sagittal and axial CT scans (without contrast) of the lumbosacral junction. Left: This sagittal reconstruction of spinal CT scans demonstrates hypoplasia of the right L-5 pedicle (arrowhead) and L4–5 foraminal stenosis. Right: An axial reconstruction of spinal CT scans demonstrates hypoplasia of the right L-5 pedicle (arrow) and pedicle defect. FIG. 4. Case 2. Left: Anteroposterior radiograph of the lumbosacral spine reveals spondylosis and mild scoliosis. Right: A neutral weight- bearing radiograph shows spondylosis and Meyerding Grade I spondy- diographic features: 1) the false appearance of an enlarged lolisthesis at the L4–S1 level. ipsilateral neural foramen because of the absent pedicle; 2) a dysplastic, dorsally displaced ipsilateral articular pillar cal examination revealed improved muscle power in bi- and lamina; and 3) a dysplastic ipsilateral transverse pro- lateral big toe dorsiflexion: MRC Grades 4/5 and 5/5 on cess. The spectrum of this anomaly also includes the ab- the right and left sides, respectively. Additionally, bilateral sence of the ipsilateral pillar or the entire ipsilateral neural ankle dorsiflexion normalized to MRC Grade 5/5. The arch, as well as other osseous anomalies in more than half dynamic radiograph of the lumbosacral spine revealed of the cases. solid bony fusion with no evidence of pseudarthrosis at The main data collected from the literature are shown the 2-year follow-up (Fig. 6). in Table 1. Previously reported cases of pedicle hypoplasia or absence were mostly asymptomatic; if present, the only symptom was low-back pain that was well controlled by Discussion conservative treatment.12,14,15,21,27 The rarer cases present- Dysgenesis or agenesis of the spinal pedicle is thought ing with intractable low-back pain or neurological impair- to result from a large retrosomatic cleft during embryo- ment required surgery.6,17,18 Most of the patients were treat- logical development.20 These clefts can occur in a variety ed with posterior instrumented fusion. However, lumbar of locations within the vertebral arch. They can also occur pedicle hypoplasia can increase the difficulties associated in the pedicles and have