Congenital Hypoplasia of the Lumbar Pedicle with Spondylolisthesis: Report of 2 Cases

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 associated 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.

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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 revealed 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 demonstrated 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 performed 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-

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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 been reported from levels T-12 with pedicle screw fixation and fusion. to S-1.4,5 Their cause is uncertain.24 Congenital hypoplasia The optimal surgical method for spondylolisthesis re- of a pedicle at the lumbosacral junction can result in ac- companying dysfunction or deformity of the facet joint, which is more critical to biomechanical stability than the hypoplasia of the pedicle itself.6 The main role of facet joints in the lumbosacral spine is to stabilize extension and rotation stress.11,22 Biomechani- cal tests have revealed that total unilateral facetectomy significantly increases the instability of the lumbosacral spine axial rotation and flexion.1 Another function of the facet joint is to distribute the axial load at each level. The load carried by facet joints varies from 9% (neutral) to 15% (extension). If one of these joints is incompetent, the contralateral joint must bear a greater load.8 Case 1 in this study showed a similar type of overload and instability in the lumbar spine, resulting in severe degenerative changes in the contralateral L4–5 facet joints. Kaito et al.6 reported a similar case that was missing the right L-5 pedicle, which led to severe degenerative changes in the contralateral facet joint. Radiological evaluation of these patients typically FIG. 6. Case 2. Six-month postoperative radiographs. Left: Antero- begins with conventional radiography and frequently in- posterior view. Right: Lateral view. The patient underwent ALIF with cludes CT, myelography, and MRI.17,23 According to Wie- SynFix cages and screws over L4–5 and L5–S1, and bilateral L-4 and ner et al.,25 this congenital anomaly has the following ra- S-1 pedicle screw fixation.

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TABLE 1. Literature summary of cases of hypoplasia or absence of lumbar pedicle Age Level & No. (yrs)/ Signs & Authors & Year of Cases Sex Symptoms Radiological Findings Management Outcome FU Patel et al., 2013 Bilat L-5, 1 13/F LBP, radiculopathy Bilat hypoplasia of L-5 VB & PI over L-4 & S-1, w/o Resolution of pain 18 mos pedicle; spondylolisthesis decompression & good bony Grade I fusion Lt S-1, 1 10/F LBP, radiculopathy Absent lt S-1 pedicle, Grade I PI over bilat L-5, rt S-1 Resolution of pain 5 mos anterolisthesis & lt S-1 alar screw & good bony w/o decompression fusion Kaito et al., 2005 Rt L-5, 1 54/M LBP, radiculopathy Absence of rt L-5 pedicle Conservative treatment NR NR Sener et al., 1991 Rt L-5, 1 34/M LBP Absence of rt L-5 pedicle Conservative treatment NR NR Polly & Mason, Rt L-6, 1 12/F LBP, radiculopathy Absence of rt L-6 pedicle, con- NR NR NR 1991 joined nerve root at L6–S1 Rt L-4, 1 14/M LBP Absence of rt L-4, T-L scoliosis Conservative treatment Resolution of pain 6 mos Lt L-5, 1 19/F LBP Absence of rt L-5 pedicle L4–S1 PLF Resolution of pain NR Rt L-5, 1 17/M LBP Absence of rt L-5 pedicle, PLF Resolution of pain NR spondylolysis Mizutani et al., Lt L-1, 1 10/M LBP Absence of lt L-1 pedicle & VB, Conservative treatment Resolution of pain 2 yrs 1989 hypoplasia of lt T-12, L-2, L-3, & L-5 pedicles Lederman & T11–12, 1 12/M Nonspecific ab pain, Hypoplasia of lt T-11 pedicle, No further workup or No back pain NR Kaufman, 1986 no LBP absence of rt T-12 pedicle therapy ab = abdominal; FU = follow-up; LBP = low-back pain; NR = not reported; PI = posterior instrumentation; PLF = posterior lateral fusion; T-L = thoracolumbar; VB = vertebral body. mains controversial. Several authors have demonstrated fusion. Further studies are necessary to corroborate our the effectiveness of ALIF in terms of the following ad- results. vantages: preservation of posterior midline complexes, low risk of neural complication, less blood loss, and high Conclusions fusion rate. Although a stand-alone ALIF cage is an effec- tive construct for low-grade spondylolisthesis, nonunion Congenital hypoplasia of the lumbar spine pedicle is and pseudarthrosis are possible complications. Recent rare. Therefore, it is important to recognize this anom- studies have shown that ALIF with PPF can be performed aly as an unusual cause of low-back and radicular pain. to attain the surgical goals and successful outcomes in Lumbar pedicle hypoplasia can increase the difficulty of the management of isthmic spondylolisthesis.2,7 However, pedicle screw fixation and fusion. Anterior lumbar inter- hypoplasia of the lumbar pedicle also increases the dif- body fusion with a stand-alone cage followed by PPF can ficulty of performing PPF. In the cases featured in this pa- provide solid fusions and avoid the difficulties associat- per, we performed PPF only for normal pedicles. We used ed with pedicle screw fixation, as demonstrated in our 2 a stand-alone cage augmented with screws to increase adult patients, in whom successful fusion and satisfactory stability given concerns of pseudarthrosis. Both patients functional outcomes were reported at the 2-year follow- underwent the combined procedures without posterior de- up. This method may be an alternative for patients with compression, and solid fusions were achieved. congenital hypoplasia of the lumbar spinal pedicle with Although Patel et al. also performed posterior instru- spondylolisthesis. mented fusion without decompression,17 2-level fusion was applied in their patients. In our study, both patients Acknowledgments underwent only single-level fusion; this allowed for the This study was supported by a grant from the Wooridul Spine preservation of adjacent normal spinal segments. Our Hospital. patients reported satisfactory functional outcomes at the 2-year follow-up. Anterior lumbar interbody fusion with a stand-alone cage followed by PPF avoids the difficulties References associated with pedicle screw fixation and provides suffi- 1. Abumi K, Panjabi MM, Kramer KM, Duranceau J, Oxland cient fusion stability. Percutaneous pedicle screw fixation T, Crisco JJ: Biomechanical evaluation of lumbar spinal has the advantages of a shorter surgical time, less paraspi- stability after graded facetectomies. Spine (Phila Pa 1976) nal muscle damage, and lower blood loss, compared with 15:1142–1147, 1990 open pedicle screw fixation. The procedures performed 2. Choi KC, Kim JS, Shim HK, Ahn Y, Lee SH: Changes in the in our cases resulted in favorable clinical outcomes and adjacent segment 10 years after anterior lumbar interbody

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fusion for low-grade isthmic spondylolisthesis. Clin Orthop or aplasia of the lumbosacral pedicle as an unusual cause of Relat Res 472:1845–1854, 2014 spondylolisthesis in the pediatric age group. J Neurosurg 3. De Boeck M, De Smedt E, Potvliege R: Computed tomogra- Pediatr 11:717–721, 2013 phy in the evaluation of a congenital absent lumbar pedicle. 18. Polly DW Jr, Mason DE: Congenital absence of a lumbar Skeletal Radiol 8:197–199, 1982 pedicle presenting as back pain in children. J Pediatr Or- 4. Dietemann JL, Macedo R, Medjek L, Babin E, Wackenheim thop 11:214–219, 1991 A: [Bilateral pedicular cleft in a patient with neurofibromato- 19. Seddon HJ (ed): Peripheral Nerve Injuries. London: HM sis (author’s transl).] Ann Radiol (Paris) 24:665–667, 1981 Stationery Office, 1954 (Fr) 20. Sener RN: Sacral pedicle agenesis. Comput Med Imaging 5. Johansen JG, McCarty DJ, Haughton VM: Retrosomatic Graph 21:361–363, 1997 clefts: computed tomographic appearance. Radiology 21. Sener RN, Ripeckyj GT, Jinkins JR: Agenesis of a lumbar 148:447–448, 1983 pedicle: MR demonstration. Neuroradiology 33:464, 1991 6. Kaito T, Kato Y, Sakaura H, Yamamoto K, Hosono N: 22. Sharma M, Langrana NA, Rodriguez J: Role of ligaments Congenital absence of a lumbar pedicle presenting with and facets in lumbar spinal stability. Spine (Phila Pa 1976) contralateral lumbar radiculopathy. J Spinal Disord Tech 20:887–900, 1995 18:203–205, 2005 23. Sheehan J, Kaptain G, Sheehan J, Jane J Sr: Congenital ab- 7. Kim KH, Lee SH, Lee DY, Shim CS, Maeng DH: Anterior sence of a cervical pedicle: report of two cases and review of bone cement augmentation in anterior lumbar interbody fu- the literature. Neurosurgery 47:1439–1442, 2000 sion and percutaneous pedicle screw fixation in patients with 24. Soleimanpour M, Gregg ML, Paraliticci R: Bilateral retroso- osteoporosis. J Neurosurg Spine 12:525–532, 2010 matic clefts at multiple lumbar levels. AJNR Am J Neuro- 8. Kornberg M: Spondylolisthesis with unilateral pars interar- radiol 16:1616–1617, 1995 ticularis defect and contralateral facet joint degeneration. A 25. Wiener MD, Martinez S, Forsberg DA: Congenital absence case report. Spine (Phila Pa 1976) 13:712–713, 1988 of a cervical spine pedicle: clinical and radiologic findings. 9. Lauten GJ, Wehunt WD: Computed tomography in absent AJR Am J Roentgenol 155:1037–1041, 1990 cervical pedicle. AJNR Am J Neuroradiol 1:201–203, 1980 26. Wortzman G, Steinhardt MI: Congenitally absent lumbar 10. Lederman HM, Kaufman RA: Congenital absence and hy- pedicle: a reappraisal. Radiology 152:713–718, 1984 poplasia of pedicles in the thoracic spine. Skeletal Radiol 27. Yousefzadeh DK, El-Khoury GY, Lupetin AR: Congenital 15:219–223, 1986 aplastic-hypoplastic lumbar pedicle in infants and young 11. Lorenz M, Patwardhan A, Vanderby R Jr: Load-bearing children. Skeletal Radiol 7:259–265, 1982 characteristics of lumbar facets in normal and surgically altered spinal segments. Spine (Phila Pa 1976) 8:122–130, 1983 Disclosures 12. Macleod S, Hendry GM: Congenital absence of a lumbar The authors report no conflict of interest concerning the materi- pedicle. A case report and a review of the literature. Pediatr als or methods used in this study or the findings specified in this Radiol 12:207–210, 1982 paper. 13. Meyerding HW: Spondylolisthesis. Surg Gynecol Obstet 54:371–379, 1932 Author Contributions 14. Mizutani M, Yamamuro T, Shikata J: Congenital absence of a lumbar pedicle. Spine (Phila Pa 1976) 14:890–891, 1989 Drafting the article: Hsieh. Critically revising the article: SH Lee. 15. Morin ME, Palacios E: The aplastic hypoplastic lumbar ped- Administrative/technical/material support: HC Lee, Hsieh, Chen. icle. Am J Roentgenol Radium Ther Nucl Med 122:639– Study supervision: HC Lee, SH Lee, Oh, Hwang, Park. 642, 1974 16. Oh YM, Eun JP: Congenital absence of a cervical spine Correspondence pedicle: report of two cases and review of the literature. J Hyung Chang Lee, Department of Cardiovascular Surgery, Korean Neurosurg Soc 44:389–391, 2008 Wooridul Spine Hospital, Gimpo Airport, 70 Haneulgil, Gang- 17. Patel AJ, Vadivelu S, Desai SK, Jea A: Congenital hypoplasia seo-gu, Seoul 155-823, Korea. email: [email protected].

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