J Korean Soc Spine Surg.  2015 Dec;22(4):178-182. 10.4184/jkss.2015.22.4.178.

Motor Weakness of Right Ankle Dorsiflexion Caused by Increasing Size of Sacroiliac Joint Cyst after Posterior Lumbar Interbody Fusion in a Patient with Spinal Stenosis: A Case Report

• Kwon JE
• Ahn YJ
• Yang BK
• Yi SR
• Lim SH
• Lee YH
• Kim HM

• KMID: 2150546
• DOI: http://doi.org/10.4184/jkss.2015.22.4.178

Abstract

STUDY DESIGN: Case report
OBJECTIVES
To report a case of motor weakness caused by the increasing size of a sacroiliac joint cyst after spinal fusion. SUMMARY OF LITERATURE REVIEW: There have been no reports on the increased size of a sacroiliac joint cyst and motor weakness after spinal fusion.
MATERIALS AND METHODS
A 63-year-old female was admitted with low back pain and right sciatica. Magnetic resonance imaging (MRI) findings showed the spinal canal narrowing at L4-5 and a cystic lesion on the right sacroiliac joint. After surgery, the symptoms were relieved.
RESULTS
One month after the operation, motor function had worsened to grade 4. Follow-up MRI revealed an increase in the size of the cystic lesion. Selective nerve root blocks were performed. There was gradual improvement, and the motor grade reached grade 5 seven months after the operation.
CONCLUSIONS
We recommend that surgeons evaluate the adjacent segmental lesion by MRI before performing spinal fusion.

Keyword

Sacroiliac joint; Cyst; Muscle weakness; Spinal stenosis; Spinal fusion

MeSH Terms

Ankle*
Female
Follow-Up Studies
Humans
Low Back Pain
Magnetic Resonance Imaging
Middle Aged
Muscle Weakness
Sacroiliac Joint*
Sciatica
Spinal Canal
Spinal Fusion
Spinal Stenosis*

Figure

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  Fig. 1. Initial magnetic resonance imaging (MRI) reveals spinal stenosis at L4–5 in the sagittal (A) and the axial (B) images, and a cystic lesion measuring 1.6 cm×1.0 cm at the inferior surface of the right sacroiliac joint in the coronal (C) image.

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  Fig. 2. Posterior decompression and posterior lumbar interbody fusion with a cage was performed at L4–5 (A, B).

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  Fig. 3. Followup MRI revealed the increased size of the cystic lesion measuring 3.3 cm×2.2 cm×1.6 cm in coronal (A) and axial (B) images (inferior and ventral aspects of the sacroiliac joint, S2–3 level).

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  Fig. 4. Followup MRI taken after three years of the operation showed a further increase in the lesion size to 4.9 cm×2.6 cm×1.8 cm in the coronal (A) and axial (B) images.

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