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Radiol Case Rep
Radiol Case Rep
Radiology Case Reports
1930-0433
Elsevier

S1930-0433(24)00708-8
10.1016/j.radcr.2024.07.121
Case Report
Lumbar pedicular agenesis: Case report and a review of the literature
Alawad Saud
Alharthi Mohammed Msm.alharthii@gmail.com
⁎
Radiology Department, King Saud Medical City, Riyadh, Saudi Arabia
⁎ Corresponding author. Msm.alharthii@gmail.com
17 8 2024
11 2024
17 8 2024
19 11 49894991
16 7 2024
18 7 2024
21 7 2024
© 2024 The Authors. Published by Elsevier Inc. on behalf of University of Washington.
2024

https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Lumbar pedicular agenesis is a rare clinical and radiological finding. Therefore, it is commonly misdiagnosed, particularly in trauma cases, with the first case being reported by Hadley in 1946.

Pedicle agenesis has specific radiographic features: a falsely appearing enlarged neural foramen; a dysplastic, dorsally displaced ipsilateral articular pillar and lamina; and a dysplastic ipsilateral transverse process.

Computed tomography (CT) is the preferred diagnostic modality for pedicle agenesis and it is important to note that pedicle agenesis is a stable congenital anomaly. Typically, these patients do not exhibit neurological deficits and are managed conservatively or receive no treatment.

In this case report, we will be reporting a case involving the absence of L5 left pedicle.

Keywords

Lumbar pedicular agenesis
Pedicle agenesis
Musculoskeletal interventional radiology
Guided intervention
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pmcIntroduction

Lumbar pedicular agenesis is a rare clinical and radiological finding. Therefore, it is commonly misdiagnosed, particularly in trauma cases [1], with the first case being reported by Hadley in 1946 [2].

Pedicle agenesis has specific radiographic features: a falsely appearing enlarged neural foramen; a dysplastic, dorsally displaced ipsilateral articular pillar and lamina; and a dysplastic ipsilateral transverse process [3].

Computed tomography (CT) is the preferred diagnostic modality for pedicle agenesis [3] and it is important to note that pedicle agenesis is a stable congenital anomaly [1]. Typically, these patients do not exhibit neurological deficits and are managed conservatively or receive no treatment.

In this case report, we will be reporting a case involving the absence of L5 left pedicle.

Literature review

The posterior arch defects of the lumbar spine arise due to intrauterine maldevelopment of the spine at 4-8 weeks of development and they are known to be rare. For instance, a cleft of the posterior arch has a prevalence of 4% while the total agenesis of the posterior arch has a prevalence of 0.15% [4], with the most common location for pedicle agenesis being at the level of C5 and C6 [1,4].

While 35% of the symptoms patients experience is related to the instability or translation of the impaired vertebral segments like neurological impairment, headaches and chronic pain, these cases are commonly diagnosed after a traumatic incident in a previously asymptomatic patient [4].

These are rare cases that seldomly require surgical treatment. Nonetheless, it is important for spine surgeons to be familiar with these anatomical abnormalities to avoid misinterpreting these radiological findings and therefore inappropriately treating them, especially in acute trauma patients [4].

Sacral pedicle agenesis is an even more rare finding, with only a few cases reported in the radiological literature [5]. Up to our knowledge, 2 cases were found in a study of osteological anatomy collection and 1 in a study that reported a 34-year-old female with right pedicle of the first sacral vertebra agenesis and an anomalous facet between L5 and S1 and was associated with developmental stenosis of the lumbar spine canal [5].

Case presentation

A 49 years old female, presented to the hospital with the chief complaint of back pain. Routine imaging of the lumbar spine was done to evaluate the area and the incidental finding of lumbar spine pedicle agenesis was noted on plain radiographic imaging as shown below (Fig. 1).Fig. 1 AP and lateral views of Lumbar Spine X-ray showing left L5 pedicle agenesis (Arrows).

Fig 1

The MRI showed hypoplastic L4 and L5 vertebral bodies associated with L5 left pedicle agenesis as well as mild lower lumbar spine disc disease, most significant at L3/4 level (Fig. 2, Fig. 3).Fig. 2 Axial view of an MRI of L5 showing absence of the left L5 pedicle (Arrow).

Fig 2

Fig. 3 Sagittal view of a T2 MRI of lumbar spine showing left L5 pedicle agenesis (Arrow).

Fig 3

Discussion

Congenital absence of the lumbar vertebral pedicle is an exceedingly rare clinical and radiological finding. Typically, this anomaly is discovered incidentally following a traumatic event or in patients presenting with chronic back pain as the primary symptom. Archer et al. provided the initial description of the embryogenesis of this anomaly, which occurs during fetal development due to the failure to develop ventral chondrification centers between 7 to 8 weeks of gestation, resulting in the absence of the pedicle.

Initially, conventional radiographs were used to identify these anomalies, followed by tomograms, and more recently, CT and MR scans are being utilized to diagnose these cases. On plain radiographs, observations such as contralateral pedicle hypertrophy, spinous process displacement, and articular process anomalies were particularly helpful in distinguishing these anomalies from lytic lesions. Some researchers suggest that MR imaging with multiplanar views provides superior evaluation compared to isolated axial CT scans for these anomalies. Additionally, MR imaging can eliminate the need for further investigation to diagnose potential neoplastic or inflammatory conditions, which are among the possible considerations in conventional radiographic assessments.

Characteristic radiographic features revealed by CT scans include ipsilateral neural foramen enlargement, dysplastic articular pillar and lamina, and dysplastic transverse process. Traumatic or tumoral diagnoses are the primary considerations, with traumatic causes often associated with facet dislocation. These absences represent stable congenital anomalies, and conservative management is typically recommended.

MRI may reveal enlarged dural sheath and increased epidural fat in the foramen but this is not always the case. Alhazmi et al. [6] demonstrated altered nerve root orientation ipsilateral to the agenesis, with a more vertical course of the cranial joining nerve root and a horizontal course of the caudal nerve, leading to a pseudo-thickening appearance in the axial plane. In lumbar cases, congenital absence of the pedicle is often associated with contralateral pedicle hypertrophy, possibly due to biomechanical stress. The literature reports few cases of congenital absence of the lumbar spine pedicle, and conservative management is generally recommended.

Conclusion

In conclusion, congenital absence of the lumbar pedicle is an exceptionally rare anomaly with unique clinical and radiological features. Typically discovered incidentally, often after traumatic events or due to chronic back pain. Its embryogenesis during fetal development underscores its congenital nature. Diagnosis primarily relies on imaging modalities such as X-rays and CT scans, revealing characteristic radiographic features indicative of this anomaly.

It is important to note that in such cases, fluoroscopy guided intervention become difficult as the pedicle is often a landmark used for guidance in different procedures such as nerve block procedures.

Despite its rarity, the literature underscores the importance of considering congenital absence of the pedicle in differential diagnoses, especially in cases presenting with traumatic incidents. Conservative management is generally recommended due to the stability of these anomalies.

Further research and reporting are crucial to better understand the prevalence, characteristics, and management strategies associated with this rare condition.

Patient consent

Written informed consent for the publication of this case report was obtained from the patient.

Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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References

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2 Hadley L.A. Congenital absence of pedicle from the cervical vertebra Am J Roentgenol Radium Ther 55 1946 193 197
3 Wiener M.D. Martinez S. Forsberg D.A. Congenital absence of a cervical spine pedicle: clinical and radiologic findings AJR Am J Roentgenol 155 5 1990 1037 1041 2120932
4 Sarotto A.J. Rosado Pardo J. Fossa Riglos S. Besse M. Cervical pedicle agenesis: case report and bibliographic review Surg Radiol Anat 42 2 2020 121 125 31664469
5 Sener R.N. Sacral pedicle agenesis Comput Med Imaging Graph 21 6 1997 361 363 9690012
6 Alhazmi R. Farmer J.P. Saint-Martin C. Magnetic resonance myelography in congenital absence of the cervical pedicle Can J Neurol Sci 44 3 2017 329 331 28073391
