Dropped head syndrome (DHS) is a disorder of the posterior neck extensor muscles that results in chin-on-chest deformity1–4 with various disabilities, such as horizontal gaze difficulty, neck pain, and gait disturbance5–9. Although these disabilities impede a patient’s quality of life, the management of DHS has not been established and remains controversial. In most cases, cervical corrective surgery is chosen for DHS because most patients present with severe neck pain and a deformed appearance of the neck with various degrees of degenerative changes in the cervical spine10–13. However, surgery for DHS may lead to unfavorable results, such as repeated mechanical failures. Recent reports have described the importance of global alignment for the treatment of DHS and suggested that the alignment parameters are related to the surgical outcome14–16. Despite these advances, a treatment strategy is yet to be established for DHS, especially in patients with concomitant thoracolumbar deformity. One controversy is which spinal part should be operated on first. This report describes 3 patients with DHS who were successfully treated with thoracolumbar corrective surgery. In each patient, neck pain and horizontal gaze difficulty improved without cervical spine surgery.
The patients were informed that data concerning their cases would be submitted for publication, and they provided consent.
Case Reports
Case 1
A 65-year-old woman was referred to our department because of severe neck pain and horizontal gaze difficulty. One year earlier, she had a vertebral compression fracture at T12 and had undergone conservative treatment with a brace for 3 months. Two months later, the neck pain and horizontal gaze difficulty became prominent and gradually deteriorated. Her symptoms did not improve with conservative treatment with cervical orthosis and physical therapy. Although the radiological examination showed a severe kyphotic deformity (T11-L1 Cobb angle= −45°) and severe spinal canal stenosis at T11-L1 on magnetic resonance imaging (Figs. 1-A through 1-E), she reported no back pain or neurological deficits. Flexion-extension cervical radiographs showed that the cervical kyphosis was flexible. The spinal sagittal parameters are shown in Table I. We performed T9-L3 posterior fusion and T11-L1 anterior corpectomy and fusion with an expandable cage (T11-L1 Cobb angle = −10°) (Fig. 1-F). After surgery, her symptoms disappeared, and cervical alignment improved without direct correction (C2-7 angle [C2-7A]: preoperative = −20°, postoperative = 12°). During her final follow-up (15 months postoperatively), the whole spinal alignment was maintained, and there was no evidence of symptom recurrence (Fig. 1-G).
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Fig. 1: A 65-year-old woman presented with severe neck pain and difficulty with a horizontal gaze. Fig. 1-A Preoperative lateral whole-spine x-ray showing thoracolumbar kyphotic deformity (T11-L1 Cobb angle = −45°) due to a T12 osteoporotic compression fracture with cervical kyphosis (arrowhead). The preoperative spinal sagittal parameters were as follows: C2-7A = −24°; C2-7 SVA = 52 mm; C7SVA = −35 mm; T1 slope = 41°; TK = 56°; LL = 47°; PI = 40°; PI-LL = −7°; and PT = 25°. Fig. 1-B Preoperative lateral flexion-extension cervical radiography indicated that cervical kyphosis remained flexible and became close to neutral with extension. Fig. 1-C Preoperative sagittal view of the CT scan showing a severe kyphotic deformity in the thoracolumbar junction with T12 collapse. Fig. 1-D Preoperative T2-weighted sagittal magnetic resonance imaging showing canal stenosis due to vertebral collapse. Fig. 1-E Postoperative sagittal view of the CT scan. T12 was replaced with an expandable cage, and the thoracolumbar deformity was corrected (T11-L1 Cobb angle = −10°). Fig. 1-F Postoperative lateral whole-spine radiograph showing indirect correction of cervical kyphosis (arrowhead) with correction of the thoracolumbar deformity. The postoperative spinal sagittal parameters were as follows: C2-7A = 12°; C2-7SVA = 33 mm; C7SVA = 5 mm; T1S = 36°; TK = 48°; LL = 41°; PI = 39°; PI-LL = −2°; and PT = 15°. C2-7 angle (C2-7A), T1 slope (T1S), C7 sacral sagittal vertical axis (C7SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI).
TABLE I -
Preoperative and Postoperative Spinal Sagittal Parameters of 3 Patients
|
Case 1 |
Case 2 |
Case 3 |
| Preoperative |
Postoperative |
Preoperative |
Postoperative |
Preoperative |
Postoperative |
| C2-7SVA, mm |
52 |
33 |
67 |
45 |
70 |
50 |
| C2-7A |
−24° |
12° |
−44° |
15° |
−34° |
−8° |
| T1 slope |
41° |
36° |
72° |
42° |
112° |
30° |
| SVA, mm |
−35 |
5 |
81 |
17 |
360 |
−20 |
| TK |
56° |
48° |
40° |
53° |
37° |
44° |
| LL |
47° |
41° |
8° |
55° |
−40° |
45° |
| PT |
25° |
15° |
27° |
20° |
35° |
17° |
| PI |
40° |
39° |
42° |
42° |
44° |
45° |
| TLK*
|
−45° |
−10° |
−52° |
−4° |
— |
— |
| PI-LL |
−7° |
−2° |
34° |
−13° |
84° |
0° |
*TLK = thoracolumbar kyphosis. Case 1 = T11-L1 Cobb, Case 2 = T12-L2 Cobb.
Case 2
A 79-year-old woman presented with severe neck pain and horizontal gaze difficulty with chin-on-chest deformity. Ten months before her initial visit, she had a vertebral compression fracture at L1. Her back pain improved after 3 months of conservative treatment with a brace. However, 2 months later, she experienced neck pain and difficulty with her horizontal gaze. Despite conservative treatment with cervical orthosis and physical therapy, the patient’s symptoms gradually deteriorated and substantially affected her quality of life. Whole-spine lateral radiographs revealed severe thoracolumbar deformity with correctable cervical kyphosis (Figs. 2-A through 2-C). We performed T4 pelvis posterior fusion with a pedicle subtraction osteotomy (PSO) at L2 (Fig. 2-D). Preoperative and postoperative T12-L2 Cobb angles were −52° and −4°, respectively. C2-7A improved from −44° to 15° indirectly (Table I). After surgery, the patient could easily look horizontally without neck pain. There was no recurrence of symptoms at the final follow-up at 18 months postoperatively (Figs. 2-E and 2-F).
Fig. 2: A 79-year-old woman presented with severe neck pain, horizontal gaze difficulty, and chin-on-chest deformity. Fig. 2-A Preoperative lateral whole-spine x-ray showing thoracolumbar kyphotic deformity (T12-L2 Cobb angle = −52°) due to an L1 osteoporotic compression fracture with cervical kyphosis (arrowhead). The preoperative spinal sagittal parameters were as follows: C2-7A = −44°; C2-7SVA = 67 mm; C7SVA = 81 mm; T1 slope = 72°; TK = 40°; LL = 8°; PI = 42°; PI-LL = 34°; and PT = 27°. Figs. 2-B and 2-C Preoperative lateral flexion x-ray and T2-weighted sagittal magnetic resonance imaging showed that cervical kyphosis remained flexible and became close to neutral with extension. Fig. 2-D Postoperative lateral whole-spine radiograph showing indirect correction of cervical kyphosis (arrowhead) with correction of thoracolumbar deformity (T12-L2 Cobb angle = −4°). Postoperative spinal sagittal parameters were as follows: C2-7A = 15°; C2-7SVA = 45 mm; C7SVA = 17 mm; T1 slope = 42°; TK = 53°; LL = 55°; PI = 42°; PI-LL = −13°; and PT = 20°. Fig. 2-E and 2-F Preoperative and postoperative photographs of the standing posture showing improvements in the sight direction (arrow). C2-7 angle (C2-7A), T1 slope (T1S), C7-sacral sagittal vertical axis (C7SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI).
Case 3
A 75-year-old man was referred to our department with severe neck pain and horizontal gaze difficulty with chin-on-chest deformity. He reported that his back had been gradually bending forward for 2 years. However, the patient reported no back pain. He started to suffer from neck pain and horizontal gaze difficulty 1 year before presentation. As shown in the whole-spine lateral radiograph (Fig. 3-A), he had severe lumbar kyphosis (pelvic incidence [PI] − lumbar lordosis [LL] = 84°), pelvic retroversion (pelvic tilt [PT] = 35°), and cervical kyphosis (C2-7A = −34°) (Figs. 3-B and 3-C) (Table I). Flexibility of cervical kyphosis was seen in flexion-extension cervical radiographs. Conservative treatment with physical therapy did not improve his symptoms. He could not gaze horizontally while standing and sitting and had difficulties with daily living, resulting in decreased social interactions. We performed T9 pelvis posterior fusion with PSO at L3. Global sagittal alignment improved as follows: PI-LL = 0° and PT = 17° (Fig. 3-D). After the surgery, his horizontal gaze difficulty and neck pain disappeared, and his gait improved remarkably. An additional movie file shows preoperative and postoperative gait in more detail (Videos 1 and 2). At the final follow-up (16 months postoperatively), except for slight kyphosis (postoperative C2-7A = −9°), no symptoms recurred, and he was satisfied with the outcome (Figs. 3-E and 3-F).
Fig. 3: A 75-year-old man presented with concerns of severe neck pain and horizontal gaze difficulty. Fig. 3-A Preoperative lateral whole-spine x-ray showed lumbar kyphosis and pelvic retroversion, as well as cervical kyphosis (arrowhead). The preoperative spinal sagittal parameters were as follows: C2-7A = −34°; C2-7SVA = 70 mm; C7SVA = 360 mm; T1 slope = 112°; TK = 37°; LL = −40°; PI = 44°; PI-LL = 84°; and PT = 35°. Fig. 3-B and 3-C Preoperative lateral flexion-extension cervical radiography indicated that cervical kyphosis remained flexible and became close to neutral with extension. Fig. 3-D Postoperative lateral whole-spine radiograph showing indirect correction of cervical kyphosis (arrowhead) with correction of global sagittal alignment. The postoperative spinal sagittal parameters were as follows: C2-7A = −8°; C2-7SVA = 50 mm; C7SVA = −20 mm; T1 slope = 30°; TK = 44°; LL = 45°; PI = 45°; PI-LL = 0°; and PT = 17°. Fig. 3-E and 3-F Preoperative and postoperative photographs of the standing posture show improvement in the sight direction (arrow). C2-7 angle (C2-7A), T1 slope (T1S), C7-sacral sagittal vertical axis (C7SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI).
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Discussion
Surgical treatment for DHS remains challenging. Treatment decisions are more complicated when patients with DHS also have thoracolumbar deformities. Although previous reports have described surgical treatment for chin-on-chest deformities with cervical corrective surgery, there have been no detailed reports on thoracolumbar corrective surgery for the treatment of DHS10–13,17. To the best of our knowledge, this study is the first case series of successful surgical treatment of DHS using thoracolumbar corrective surgery alone. The chief concerns of the patients, namely, severe neck pain and horizontal gaze difficulty, were resolved without performing any direct procedure on the cervical spine. These results suggest that chin-on-chest deformity and related concerns could be caused by the pathology of the thoracolumbar spine.
The importance of spinopelvic sagittal alignment in patients with DHS has recently been discussed. Hashimoto et al. reported that DHS could be classified into sagittal vertical axis (SVA)+ and SVA−. The compensatory functions in the SVA− group, including the hyperlordotic lumbar spine, result in the backward shifting of the load axis. By contrast, in the SVA+ group, compensatory functions in the thoracolumbar spine and pelvis to chin-on-chest deformity were compromised15. Kudo et al. also reported that patients with DHS could be classified into 3 types using PI-LL and SVA as the compensatory function and load axis reference, respectively16. This report also found that most DHS patients with thoracolumbar deformity required additional thoracolumbar corrective surgery because of the recurrence of symptoms or mechanical failure even after achieving horizontal gaze with cervical surgery. Both authors emphasized that assessment of thoracolumbar alignment parameters is warranted for all surgical candidates. Moreover, they stated that the symptoms and chin-on-chest deformity could be improved only with thoracolumbar corrective surgery in certain patients.
In general, thoracolumbar spine deformities cause cervical hyperlordosis to maintain a horizontal gaze. The resolution of cervical hyperlordosis as a reciprocal change after surgical correction of thoracolumbar sagittal malalignment has been reported by Smith et al.18,19 However, it is also known that severe cervical kyphosis observed in patients with DHS may induce compensatory thoracolumbar hyperlordosis20. Koda et al. reported resolution of lower back symptoms after cervical corrective surgery in patients with DHS21. Therefore, the corrective surgery in one region of the spine influences the alignment of other areas of the spine.22
All 3 of our patients had severe problems with global alignment in the thoracolumbar junction (Case 1: T11-L1 Cobb angle = −45°; Case 2: T12-L2 Cobb angle = −52°) and lumbar spine (Case 3: PI-LL = 88°) accompanied with cervical kyphosis (C2-7A: Case 1 = −24°, Case 2 = −44°, Case 3 = −34°) simultaneously. Thoracolumbar kyphosis due to vertebral compression fracture and “bent back” were triggers of their symptoms. We postulated that severe stress on the neck extensor muscles disrupted the compensation mechanism in the cervical spine, resulting in the symptoms and chin-on-chest deformity. Therefore, performing cervical corrective surgery and leaving the thoracolumbar deformity may have led to postoperative distal junctional failure due to stress concentration under unfavorable global spinal alignment. For these reasons, we performed thoracolumbar corrective surgery for these 3 patients and expected indirect correction of cervical kyphosis and improvement of the symptoms. Considering the surgical results, thoracolumbar corrective surgery before cervical surgery could be a reasonable choice in patients with DHS accompanied by thoracolumbar deformities.
One of the most challenging issues for this “thoracolumbar-first strategy” is that it is often difficult for patients to understand the necessity of thoracolumbar surgery because the main symptoms are seemingly related to the cervical spine. The expectations of patients and surgeons may not align, especially for complex spinal pathologies23. In addition, previous reports have discussed that patients’ suboptimal understanding is associated with worse patient satisfaction24. Surgeons should be aware of this issue and spend time educating their patients.
Although the surgical outcomes of these 3 cases were excellent, there are some limitations. While we propose a strategy to manage complex conditions, we cannot prove that our approach is superior to other strategies because of the small number of patients. Second, the long-term clinical outcomes of these patients remain unknown. Third, because thoracolumbar corrective surgeries are usually highly invasive for elderly patients, the indication of this strategy is limited to relatively healthy patients. Finally, our treatment strategy cannot be applied to fixed deformities, such as ankylosing kyphosis, because we cannot expect an indirect correction. Further studies with a large number of patients and long follow-up periods are required to establish the effectiveness of this approach.
In this case report, we presented 3 cases of DHS being successfully treated with thoracolumbar corrective surgery alone. Improvements in neck pain, horizontal gaze difficulty, and indirect correction of chin-on-chest deformity were obtained without cervical surgery. Surgeons should consider the possibility of thoracolumbar spine deformity being the main cause of typical DHS symptoms and recognize thoracolumbar corrective surgery as an effective option for treating DHS patients with thoracolumbar deformity.
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