Abstract

Background: Acrodysostosis (ACRO) is a rare disorder of peripheral bone development which can be either sporadic or inherited with mutations in the PRKAR1A or PDE4D genes. The resulting phenotypical characteristics are variable and overlap with other dysostosis conditions, making diagnosis difficult without genotyping. Vertebral malformations have been reported with ACRO resulting in slowly progressive spinal cord compression leading to radiculopathy or myelopathy.

Case Description: A 19-year-old female diagnosed with ACRO presented with progressively worsening lower extremity paraparesis, sensory loss, and urinary retention; she was wheelchair-bound. A magnetic resonance imaging showed cord signal change at the T2/T3 levels with accompanying diffuse cord edema between T6-T8. Six months following a T2/T3 and T6/T7 laminectomy, the patient’s symptoms improved, but she still required a wheelchair.

Conclusion: Patients with ACRO should be regularly monitored for cord compression to allow for early surgical decompression to prevent long-term, devasting neurological compromise.

Keywords: Acrodysostosis, Laminectomy, Neurosurgery

INTRODUCTION

Acrodysostosis (ACRO) is a disorder in peripheral bone development initially described in 1968 by Maroteaux.[ 4 ] It is a member of the dysostoses, characterized by bone malformations attributed to blastogenesis abnormalities.[ 6 ] It is a rare pathology, with <70 cases reported in the literature.[ 9 ] Signature characteristics of the disease include: brachydactyly affecting all metacarpals, diffuse peripheral dysostosis, short stature, skull hypoplasia, maxillonasal hypoplasia, and shortened interpedicular distance due to premature closure of vertebral epiphyses, which contributes to spinal stenosis.[ 3 ] Case reports of familial inheritance identified two genes, PRKAR1A and PDE4D, which are responsible for ACRO.[ 7 ] Here, we discuss a patient with ACRO who presented with thoracic myelopathy requiring T2/3 and T6-8 decompressive laminectomies.

CASE DESCRIPTION

A 19-year-old female with a history of ACRO presented with a 3-month complaint of progressive paraparesis leading to paraplegia, a loss of pinprick sensation at the T4 level, and urinary retention. Magnetic resonance imaging showed central canal stenosis that was more prominent on the left, cord signal change at the T2/T3 level [ Figures 1 and 2 ], and diffuse cord edema from the T6-T8 levels [ Figures 3 and 4 ]. She underwent T2/T3 and T6/T7 level laminectomies and was discharged on postoperative day 4. Despite surgical decompression, at 3-month follow-up, she still had significant residual paraparesis, urinary retention, and required a wheelchair.

Figure 1:

(a) Sagittal T2-weighted magnetic resonance imaging (MRI) of the cervical spine showing a hyperintensity and buckling of ligamentum flavum (circle) at T2-T3 and canal stenosis (arrows) at multiple levels. (b) Sagittal T1-weighted MRI showing hypointensity and buckling of the ligamentum flavum (circle) at T2-T3 and canal stenosis (arrows) at multiple levels. (c) Sagittal short T1-weighted inversion recovery (STIR) MRI showing hyperintensity and buckling of the ligamentum flavum (circle) at T2-T3 consistent with cord edema and canal stenosis (arrow) at multiple levels.

Figure 2:

(a) Axial T1-weighted FLAIR MRI at T2/T3 level showing thickening/hypertrophy of ligamentum flavum (solid arrows) and decreased spinal canal diameter. (b) Axial T2-weighted MRI at the T2/T3 level showing thickening/hypertrophy of ligamentum flavum (solid arrows) and cord signal change (dashed arrows) moreprominent on the left than the right.

Figure 3:

(a) Sagittal T2-weighted MRI showing a hyperintensity of the cord and buckling of ligamentum flavum (circle) at T2-T3, diffuse hyperintensity (oval) from T6-T8, and lumbar stenosis (arrows). (b) Sagittal T1-weighted MRI showing hypointensity of the cord and buckling of the ligamentum flavum (circle) at T2-T3, diffuse hypointensity (oval) from T6-T8, and lumbar stenosis (arrows). (c) Sagittal short T1-weighted inversion recovery (STIR) MRI showing hyperintensity and buckling of the ligamentum flavum (circle) at T2-T3 consistent with cord edema, diffuse hyperintensity (oval) from T6-T8, and lumbar stenosis (arrow).

Figure 4:

(a) Axial T1-weighted FLAIR MRI at T6/T7 level showing thickening/hypertrophy of ligamentum flavum (solid arrows) and slight cord change (dashed arrows). (b) Axial T2-weighted MRI at T6/T7 level showing thickening/hypertrophy of ligamentum flavum (solid arrows) and slight cord change (dashed arrows).

DISCUSSION

We found only five instances of ACRO that were myelopathic and attributable to MR-documented stenosis. [ Table 1 ] Three out of five cases underwent surgical treatment, with the other two undergoing medical management.[ 1 - 3 , 5 , 8 ] One case similar to ours involved a 22-year-old man with mild left lower extremity motor paresis (4/5) and left T4–5 sensory level. One month following a T3–5 laminectomy, the patient could ambulate, and the postoperative MR showed adequate spinal cord decompression.[ 3 ]

Table 1:

Table showing the characteristics of acrodysostosis patients with neurological deficits reported in the literature, including our case, listing the patient’s presenting signs/symptoms, imaging findings, treatment approach, and length of follow-up.

Acrodysotosis: Differential diagnostic considerations

The differential diagnostic considerations for ACRO include idiopathic hypercalcemia, pseudohypoparathyroidism, and ankylosing spondylitis (AS).[ 9 , 10 ] More detailed discussions of these differentials in addition to other characteristics of ACRO is outside the scope of this paper , but can be found in the summarized literature [ Table 2 ]. While most ACRO cases are sporadic, there is also a hereditary component.[ 7 ] One may use a similar screening and monitoring algorithm for ACRO as that applied to AS, a component of which may include genetic testing [ Figure 5 ].

Table 2:

Table of included references as well as summaries of the articles.

Figure 5:

Our proposed algorithm for screening and diagnosing acrodysostosis and preventing complications before they arise or treating them before severe neurological deficits set in.

CONCLUSION

Patients with ACRO, either sporadic or genetic in origin, should be routinely monitored for the onset of radiculopathy and/or myelopathy reflecting progressive cord compromise due to stenosis, which may or may not warrant surgical spinal decompression.

Declaration of patient consent

Patient’s consent not required as patient’s identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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