Unusual cause of dorsal compressive myelopathy - Double butterfly vertebra mimicking vertebral fracture

Dig Vijay Singh Thakur; Nisarg Parmar; Rakesh Kumar Mishra; Bhagavatula Indira Devi

doi:10.4103/joss.joss_3_21

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CASE REPORT

Year : 2022 | Volume : 9 | Issue : 1 | Page : 59-61

Unusual cause of dorsal compressive myelopathy - Double butterfly vertebra mimicking vertebral fracture

Dig Vijay Singh Thakur, Nisarg Parmar, Rakesh Kumar Mishra, Bhagavatula Indira Devi
Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

Date of Submission	01-Jul-2021
Date of Acceptance	26-Dec-2021
Date of Web Publication	9-Mar-2022

Correspondence Address:
Bhagavatula Indira Devi
Department of Neurosurgery , NIMHANS, Bengaluru, Karnataka
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/joss.joss_3_21

Abstract

Structural developmental anomalies affecting the vertebral column resulting in malformed vertebrae are numerous. It can arise secondary to errors of vertebral formation, fusion and/or segmentation and developmental variation. These anomalies can occasionally mimic acute trauma and predispose the affected individual to compressive myelopathy. A butterfly vertebrae is a rare form of congenital vertebral segmentation anomaly resulting from symmetric fusion defect. It can easily be confused with burst fracture, hence though rare, we should be aware of this anomaly for a correct diagnosis while treating a patient.

Keywords: Compressive myelopathy, developmental anomalies, double butterfly vertebrae, vertebral fracture

How to cite this article:
Singh Thakur DV, Parmar N, Mishra RK, Devi BI. Unusual cause of dorsal compressive myelopathy - Double butterfly vertebra mimicking vertebral fracture. J Spinal Surg 2022;9:59-61

How to cite this URL:
Singh Thakur DV, Parmar N, Mishra RK, Devi BI. Unusual cause of dorsal compressive myelopathy - Double butterfly vertebra mimicking vertebral fracture. J Spinal Surg [serial online] 2022 [cited 2023 Mar 21];9:59-61. Available from: http://www.jossworld.org/text.asp?2022/9/1/59/339269

Introduction

Vertebral column is formed in early gestation period in a sequential manner and disruption of this sequence of events can lead to various anomaly of the spine.^[1] Vertebral malformations due to disordered assimilation or fusion include butterfly vertebra and dysplastic spondylolysis.^[2] Butterfly vertebrae was first described in 1844 by Rokitansky in a 55-year-old gentleman on examining 12^th thoracic vertebra.^[3] It manifests as a sagittal cleft between the unfused sclerotomal pairs. Although usually asymptomatic, this can be mistaken for compression, burst or wedge fractures on imaging.^[2] We report a case of young boy presenting with symptom of compressive myelopathy with butterfly vertebra on dorsal cord and vertebral body fusion.

Case Report

A 16-year-old boy presented with insidious onset gradually progressive history of low back pain with weakness of left lower limb followed by right lower limb along with decreased sensation to touch and temperature below umbilicus from last 1 month. No bladder bowel disturbances were present. On examination, vitals normal, no tenderness or gibbus noted at the back. The patient had no kyphoscoliosis. On motor examination, spasticity and hyperreflexia were present in both lower limb with lower limb power 3/5. Upper limb had normal power, tone, and reflexes. Abdominal reflex was absent bilateral below T10. On sensory examination, the patient had decreased sensation to hot and cold as well as touch sensation below iliac crest up to 50%. On investigation, routine blood investigations were normal. Computed tomography spine showed multiple level fused vertebra (D8-10) and butterfly vertebrae at D10-D11 level with secondary spinal canal stenosis [Figure 1]. MRI dorsolumbar spine showed segmental deformity of the thoracic spine with butterfly vertebrae at D10-D11 level with protrusion of vertebra compressing the spinal cord [Figure 2]a and [Figure 2]b. The patient underwent decompressive laminectomy at D9-D11 level with partial excision of protruding bone, arising from the lamina and pedicle, which was causing compression [Figure 2]c. No fixation was done as the patient had no kyphoscoliosis. Postoperative patient recovered well from anesthesia with the improvement of power of both lower limbs to 4/5 and sensory disturbance gradually improved to 90%. The patient was advised physiotherapy and discharged. On follow-up at 6 months, the patient was able to perform normal daily activities with no spasticity or weakness.

Figure 1: Computed tomography spine coronal (a) view showing 2 butterfly vertebrae at level D10-D11 with fusion of vertebral segments D8-D10. Sagittal view (b) showing displacement of vertebral segment of butterfly vertebrae D 10 posterior

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Figure 2: Magnetic resonance imaging spine sagittal (a) axial view (b) showing displacement of D10 butterfly vertebral segment posteriorly causing significant spinal cord compression with cord signal changes, (c) Sagittal view whole spine post decompressive laminectomy status

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Discussion

Butterfly vertebrae occur as an aberration in the normal embryological development of the vertebral body. The first stage of development of the spine is neurulation with formation of the notochord at day 7 during gastrulation.^[4] It is followed by migration of endodermal cells and formation of lateral mesoderm. Somatization of the mesoderm proceeds with the formation of 44 pairs of somites-blocks of tissue on either side of the neural tube.^[5] The mesoderm is also responsible for the formation of cardiac, pulmonary, and renal tissue-hence high association of vertebral anomalies with disturbances of other major organ systems.^[4] A butterfly vertebra is said to be the result of a sagittal cleft caused by the persistence of the notochord. Sixty-one percent of patients presented with a single butterfly vertebra, while 39% were multiple. The most common location for butterfly vertebrae was T1. Overall, the most common presenting complaint was low back pain. Seventy percent of patients had associated spinal disease.^[1] It is often associated with rib and/or vertebral anomalies such as bars, supernumerary lumbar vertebrae, and spina bifida.^[1] In our case, the patient has 2 butterfly vertebrae at D9 and D10 with fusion of vertebral body from D8-D10. In the lateral radiograph, the butterfly vertebra shows either trapezoidal or cuneiform anterior wedging mimicking compression fracture. Various points which can help differentiate butterfly vertebrae from fracture are the adjacent vertebrae will show features of long-standing deformity such as exaggerated elongation anterior margins to occupy the defect and a normal intervertebral disc.^[6] The butterfly vertebra can be diagnosed in an AP radiograph because vertebra is split into lateral halves or hemivertebra, and they can be of same or different size. Butterfly vertebrae might increase the incidence of disc herniation causing compression of spinal cord through various mechanisms. Some of the mechanisms explained are-absence of a normal disc between two vertebrae may alter the spinal biomechanics causing disc protrusion and spinal cord compression^[7] Another mechanism advocated is congenital reduction or lack of vascularisation of the butterfly vertebrae leading to anterior aplasia, which may be associated with kyphosis and potentially serious spinal cord compression.^[8] Only few cases with symptomatic disc herniation are reported which require decompression.^[9] The study is similar to our case which also required decompressive surgery for relief of symptoms.

Conclusion

In summary, despite the rarity of butterfly vertebrae, compressive myelopathy signifies an alarming medical complication that is rarely prescribed to the butterfly vertebrae of the thoracic spine. The workup of these symptoms often might exceed the narrow window of opportunity to surgically decompress the spinal cord before permanent paraplegia ensues. The radiologist can alert the clinician to the likelihood of a serious complication arising secondary to such abnormalities and assist in the preoperative workup and postoperative follow-up. Informing the patient about this anomaly may avoid further invasive and noninvasive procedures.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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