Abstract
Peripheral injury-induced movement disorders encompass a broad spectrum of conditions characterized by involuntary movements resulting from injuries to the peripheral nervous system. While most reported cases are associated with traumatic events—such as nerve lacerations—surgical interventions are also recognized as potential triggers of such disorders. This article aims to report a rare presentation of dancing dorsal quadrilateral syndrome (DDQS) following spinal surgery with instrumentation. A 63-year-old man presented with back pain and neck pain and was diagnosed with Scheuermann’s disease. He underwent thoracic spinal fusion with pedicle screw instrumentation to correct hyperkyphosis. Six months after surgery, he began to experience a burning pain in the bilateral subscapular region along with abnormal and involuntary movements in the dorsal musculature. The motor unit potential followed an ascending-descending pattern, and these findings were compatible with dyskinesia, specifically DDQS. A joint management approach with a clinical neurologist was indicated, including the prescription of muscle relaxants and the administration of botulinum toxin in the dorsal quadrilaterals, resulting in partial improvement of the condition. Treatment options range from addressing afferent nerve injury, which can sometimes be curative in some focal dyskinesias, to the use of botulinum toxin for symptomatic relief, as presented in the above case. Additional research is warranted to better understand the pathophysiology of DDQS and to optimize treatment strategies for this uncommon but clinically significant condition.
Introduction
Peripheral injury–induced movement disorders encompass a broad spectrum of conditions characterized by involuntary movements resulting from injuries to the peripheral nervous system.1 While most reported cases are associated with traumatic events—such as nerve lacerations—surgical interventions are also recognized as potential triggers of such disorders.2 Among these, spinal surgeries involving instrumentation have been linked to a rare condition known as dancing dorsal quadrilateral syndrome (DDQS). This syndrome is marked by sustained contractions and sudden, irregular movements of the rhomboid (dorsal quadrilateral) and trapezius muscles.3 The present article aims to report a rare presentation of DDQS following spinal surgery with instrumentation.
Case Report
A 63-year-old man presented with back pain and neck pain and was diagnosed with Scheuermann’s disease. He underwent thoracic spinal fusion with pedicle screw instrumentation from T3 to L1 on 16 May 2024 to correct hyperkyphosis, resulting in improvement of symptoms (Figure 1). Cervical spine magnetic resonance imaging was performed to rule out alternative cervical etiologies that could contribute to the patient’s clinical presentation (Figure 2). Six months after surgery, he began to experience a burning pain in the bilateral subscapular region, along with abnormal and involuntary movements in the dorsal musculature. The patient reported that the movements disappeared when he performed a voluntary contraction of the dorsal muscles, while lying down, and especially when sleeping. In contrast, it worsened when sitting or, particularly, when adopting an upright position. During the physical examination, involuntary, slow, and rhythmic movements of the dorsal musculature were observed, which quickly subsided when the patient adopted the supine or lateral position or when cutaneous sensory stimulation was applied manually during the physical examination (Supplemental Video 1).
Sagittal and coronal images from computed tomography, bone window, of the postoperative phase showing the surgical instrumentation of thoracic arthrodesis.
Sagittal T2-weighted magnetic resonance imaging of the cervical spine shows no evidence of spinal cord compression or signal abnormalities that could explain the patient’s symptoms. Cervical alignment is preserved, and no significant disc herniation or protrusion is observed.
The patient underwent an electromyography examination (Figure 3), which revealed spontaneous activity in the form of groupings of motor units activated in a semi-rhythmic pattern, with a frequency of approximately 7–8 Hz in the upper, middle, and lower thoracic paravertebral musculature (levels T5–T10) and scapular musculature (rhomboids and trapezius muscles bilaterally), with greater amplitude on the right side. The motor unit potential followed an ascending-descending pattern, and these findings were compatible with dyskinesia, specifically DDQS. A joint management approach with a clinical neurologist was indicated, including the prescription of muscle relaxants and the administration of botulinum toxin type A at a total dose of 300 units, which was divided and injected bilaterally into the dorsal quadrilateral muscles and resulted in partial improvement of the condition.
Electroneuromyographic findings showing spontaneous grouped motor unit discharges in a semi-rhythmic pattern (~7–8 Hz) involving the thoracic paravertebral muscles (T5–T10) and scapular muscles (rhomboids and trapezius bilaterally), more prominent on the right. Activity intensified with trunk extension and is consistent with dancing dorsal quadrilaterals syndrome (DDQS). No evidence of myopathy, thoracic (T1–T12) or cervical (C5–C6) motor radiculopathy, or anterior horn cell involvement was found at the time of the study.
Discussion
DDQS is a movement disorder induced by peripheral trauma affecting the scapular musculature (trapezius and rhomboids) and adjacent muscles. This focal dyskinesia clinically resembles dystonia owing to the semirhythmic, repetitive movements, maintained posture, and improvement in the supine position; however, it differs by showing improvement during active movements.3
DDQS typically occurs after extensive posterior dorsal instrumentation, as in the presented case, potentially due to peripheral cutaneous and intramuscular nerve injury, leading to central sensorimotor reorganization. Improvement with intentional movement and bilateral movements suggests central involvement in the pathophysiology of this dyskinesia, while studies in animal models suggest that persistent afferent peripheral injury may induce a hyperglutamatergic state, reducing responses in segmental and suprasegmental inhibitory neurons.3 The exact nerve or nerves injured during surgery were not directly identified. However, based on the clinical features, the semiology of the involuntary movements, and the electromyographic findings—particularly the semi-rhythmic motor unit discharges localized to the paravertebral and scapular muscles—the most plausible explanation involves injury or dysregulation of afferent fibers carried by the dorsal rami of the cervical and thoracic spinal nerves. These nerves provide sensory input to the trapezius and rhomboid muscles (collectively referred to as the dorsal quadrilateral muscles), and their dysfunction may contribute to the abnormal sensorimotor feedback loops underlying the syndrome.
The condition consists of semirhythmic, abrupt movements, more evident in sitting or standing positions, with significant improvement in the supine position, active voluntary movement, sensory stimulation, and sleep. Similar to other focal dyskinesias, such as the belly dancer syndrome, a pattern on electromyography similar to dystonia is observed, with motor unit discharges of up to 500 ms and frequencies of up to 6 Hz, a pattern similar to that of dystonias. The delayed onset of symptoms is most likely explained by progressive central sensorimotor reorganization following a partial and chronic peripheral nerve injury. After the initial insult—presumably affecting cutaneous or intramuscular afferents from the dorsal rami of cervical and thoracic spinal nerves—a latent period may ensue, during which maladaptive neuroplastic changes gradually emerge within the central nervous system. This process may involve altered sensory processing, abnormal excitability of spinal interneurons, and disinhibition of motor pathways, eventually manifesting as involuntary movements and neuropathic pain. Such delayed presentations are not uncommon in movement disorders following peripheral nerve injury. Treatment options range from addressing afferent nerve injury, which can sometimes be curative in some focal dyskinesias, to the use of botulinum toxin for symptomatic relief, as presented in the above case.4
Conclusions
DDQS represents a rare and often underdiagnosed form of peripherally induced movement disorder, typically emerging after spinal surgeries involving extensive instrumentation. This case highlights the importance of clinical awareness in identifying such postoperative complications. Early recognition and the use of botulinum toxin can offer significant symptomatic relief and improve patient quality of life. Currently, there are no established, evidence-based preventive strategies for DDQS given its rarity and unclear pathophysiology. Further research is warranted to better understand the pathophysiology of DDQS and to optimize treatment strategies for this uncommon but clinically significant condition.
Supplementary material
Supplemental Video 1.
During the physical examination, involuntary, slow, and rhythmic movements of the dorsal musculature were observed, which quickly subsided when the patient adopted the supine position.Footnotes
Funding The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests The authors report no conflicts of interest in this work.
- This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2025 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.
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