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Mitsuru Yagi, Ken Ninomiya, Michiya Kihara and Yukio Horiuchi

Whereas osteochondroma is a common benign bone tumor in adolescence, it is rarely observed in elderly patients. It is unknown why osteochondromas, which usually develop during skeletal growth, rarely develop in elderly patients. The authors report 3 cases of symptomatic spinal osteochondroma in elderly patients and discuss the possible reasons for the onset of the enlargement of osteochondromas in elderly patients.

Clinical history, radiographs, MR images, and CT myelography studies were obtained in each patient and are described. A review of the relevant literature is also presented. In the first case, the cervical osteochondroma caused spinal canal compression and occipital nerve irritation. It was totally excised, which successfully relieved the pain and allowed the patient to return to normal neurological function. In the second case, total removal of the tumor was effective in alleviating clinical symptoms. In the last case, ablation of the articular facet joint partially relieved the patient's lower-back pain. In the first 2 cases, the patients suffered from psoriasis and associated psoriatic arthritis and in the last case, the patient suffered from HIV-associated psoriatic arthritis. The psoriatic arthritis was characterized as asymmetric chronic multiple-joint arthritis and was HLA B27 positive. The pathology of psoriatic arthritis was the accelerating bone turnover and ankylosis.

Symptomatic osteochondroma of the spine in elderly patients is extremely rare since it typically develops during skeletal growth. In this report, the authors show that pathological accelerating bone turnover such as psoriatic arthritis may be a possible mechanism for the onset of the enlargement of osteochondromas in elderly patients. The age of the patients in this report suggests that growth of the osteochondroma continues after skeletal development.

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Mitsuru Yagi, Ken Ninomiya, Michiya Kihara and Yukio Horiuchi

Object

The goal of this study was to determine the long-term clinical significance of and the risk factors for intramedullary signal intensity change on MR images in patients with cervical compression myelopathy (CCM), an entity most commonly seen with cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament (OPLL).

Methods

One hundred seventy-four patients with CCM but without cervical disc herniation, severe OPLL (in which the cervical canal is < 10 mm due to OPLL), or severe kyphotic deformity (> 15° of cervical kyphosis) who underwent surgery were initially selected. One hundred eight of these patients were followed for > 36 months, and the 71 patients who agreed to MR imaging examinations both pre- and postsurgery were enrolled in the study (the mean follow-up duration was 60.6 months). All patients underwent cervical laminoplasty. The authors used the Japanese Orthopaedic Association (JOA) score and recovery ratio for evaluation of pre- and postoperative outcomes. The multifactorial effects of variables such as age, sex, a history of smoking, diabetes mellitus, duration of symptoms, postoperative expansion of the high signal intensity area of the spinal cord on MR imaging, sagittal arrangement of the cervical spine, presence of ventral spinal cord compression, and presence of an unstable cervical spine were studied.

Results

Change in intramedullary signal intensity was observed in 50 of the 71 patients preoperatively. The pre- and postoperative JOA scores and the recovery ratio were significantly lower in the patients with signal intensity change. The mean JOA score of the upper extremities was also significantly lower in these patients. Twenty-one patients showed hypointensity in their T1-weighted images, and a nonsignificant correlation was observed between intensity in the T1-weighted image and the mean JOA score and recovery ratio. The risk factors for signal intensity change were instability of the cervical spine (OR 8.255, p = 0.037) and ventral spinal cord compression (OR 5.502, p < 0.01). Among these patients, 16 had postoperative expansion of the high signal intensity area of the spinal cord. The mean JOA score and the recovery ratio at the final follow-up were significantly lower in these patients. The risk factor for postoperative expansion of the high signal intensity area was instability of the cervical spine (OR 5.509, p = 0.022). No significant correlation was observed between signal intensity on T1-weighted MR images and postoperative expansion of the intramedullary high signal intensity area on T2-weighted MR images.

Conclusions

Long-term clinical outcome was significantly worse in patients with intramedullary signal intensity changes on MR images. The risk factors were instability of the cervical spine and severe ventral spinal compression. The long-term clinical outcome was also significantly worse in patients with postoperative expansion of the high signal intensity area. The fact that cervical instability was a risk factor for the postoperative expansion of the high signal intensity indicates that this high signal intensity area occurred, not only from necrosis secondary to ischemia of the anterior spinal artery, but also from the repeated minor traumas inflicted on the spinal cord from an unstable cervical spine. The long-term neurological outcome found in the preliminary study of patients with CCM who had cervical instability and intramedullary signal intensity changes on MR images suggests that surgical treatment should include posterior fixation along with cervical laminoplasty or anterior spinal fusion.

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Mitsuru Yagi, Eijiro Okada, Ken Ninomiya and Michiya Kihara

Object

The object of this study was to assess the feasibility and efficacy of a novel, minimally invasive spinal surgery technique to correct degenerative lumbar spinal stenosis involving a modified unilateral-approach microendoscopic midline decompression.

Methods

In this prospective study, 41 patients with lumbar stenosis were randomly assigned to undergo either a novel, median-approach microendoscopic laminectomy (20 patients) or a conventional laminectomy (21 patients). Spinal anteroposterior diameter, cross-sectional area, lateral recess distance, spinal stability, postoperative back pain, functional outcomes, and muscle trauma were evaluated. Follow-up ranged from 16 to 24 months, with a mean of 17.8 months for the novel procedure group and 18.6 months for the conventional laminectomy group.

Results

Compared with patients in the conventional laminectomy group, patients who received the novel procedure had a reduced mean duration of hospital stay, a lower mean creatine phosphokinase muscular-type isoenzyme level, a lower visual analog scale score for back pain at 1-year follow-up, and a faster recovery rate. These patients also had less mean blood loss compared with the conventionally treated group. Satisfactory neurological decompression and symptom relief were achieved in 90% of these patients. There was no significant clinical difference compared with the conventional laminectomy group's results. There was no evidence of spinal instability in any patient, and no patient required a follow-up conventional laminectomy.

Conclusions

This novel procedure provides effective spinal decompression. Although this method requires more operating time than a conventional method, it requires only minimal muscle trauma and spinal stability maintenance, and allows for early mobilization. This shortens the hospital stay, reduces postoperative back pain, and leads to satisfactory neurological and functional outcomes. Moreover, with the midline approach, decompression was accomplished without compromising the facet joints, even with a narrow width of lamina.

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Christopher I. Shaffrey, Justin S. Smith, Christopher P. Ames, Mitsuru Yagi, Ahmet Alanay and Yoon Ha

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Editorial

Magnetic resonance imaging and outcome

Michael G. Fehlings and Babak Arvin

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Narihito Nagoshi, Osahiko Tsuji, Daisuke Nakashima, Ayano Takeuchi, Kaori Kameyama, Eijiro Okada, Nobuyuki Fujita, Mitsuru Yagi, Morio Matsumoto, Masaya Nakamura and Kota Watanabe

OBJECTIVE

Intramedullary cavernous hemangioma (CH) is a rare vascular lesion that is mainly characterized by the sudden onset of hemorrhage in young, asymptomatic patients, who then experience serious neurological deterioration. Despite the severity of this condition, the therapeutic approach and timing of intervention for CH remain matters of debate. The aim of this study was to evaluate the clinical characteristics of CH patients before and after surgery and to identify prognostic indicators that affect neurological function in these patients.

METHODS

This single-center retrospective study included 66 patients who were treated for intramedullary CH. Among them, 57 underwent surgery and 9 patients received conservative treatment. The authors collected demographic, symptomology, imaging, neurological, and surgical data. Univariate and multivariate logistic regression analyses were performed to identify the prognostic indicators for neurological function.

RESULTS

When comparing patients with stable and unstable gait prior to surgery, patients with unstable gait had a higher frequency of hemorrhagic episodes (52.4% vs 19.4%, p = 0.010), as assessed by the modified McCormick Scale. The lesion was significantly smaller in patients who underwent conservative treatment compared with surgery (2.5 ± 1.5 mm vs 5.9 ± 4.1 mm, respectively; p = 0.024). Overall, the patients experienced significant neurological recovery after surgery, but a worse preoperative neurological status was identified as an indicator affecting surgical outcomes by multivariate analysis (OR 10.77, 95% CI 2.88–40.36, p < 0.001). In addition, a larger lesion size was significantly associated with poor functional recovery in patients who had an unstable gait prior to surgery (8.6 ± 4.5 mm vs 3.5 ± 1.6 mm, p = 0.011).

CONCLUSIONS

Once a hemorrhage occurs, surgical intervention should be considered to avoid recurrence of the bleeding and further neurological injury. In contrast, if the patients with larger lesion presented with worse preoperative functional status, surgical intervention could have a risk for aggravating the functional deficiencies by damaging the thinning cord parenchyma. Conservative treatment may be selected if the lesion is small, but regular neurological examination by MRI is needed for assessment of a change in lesion size and for detection of functional deterioration.

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Sanjeev Ariyandath Sreenivasan, Kanwaljeet Garg, Manmohan Singh and Poodipedi Sarat Chandra

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Satoshi Nori, Akio Iwanami, Akimasa Yasuda, Narihito Nagoshi, Nobuyuki Fujita, Tomohiro Hikata, Mitsuru Yagi, Takashi Tsuji, Kota Watanabe, Suketaka Momoshima, Morio Matsumoto, Masaya Nakamura and Ken Ishii

OBJECTIVE

A number of studies have reported that surgery for cervical intramedullary tumors via the posterior approach can result in postoperative sagittal malalignment of the cervical spine; however, the risk factors remain unclear. The purpose of this study was to investigate the changes in cervical spinal alignment after surgery for cervical intramedullary tumors in adults and to elucidate the risk factors for cervical spinal sagittal misalignment.

METHODS

Data for the period from April 2001 to December 2011 for all adults who had undergone surgery for cervical intramedullary spinal cord tumors at a single institution were retrospectively analyzed to determine the postoperative changes in cervical spine alignment. Patients younger than 20 years of age and those who required postoperative radiotherapy were excluded from the study. Patients were divided into 2 groups according to tumor location: upper tumor (U) group, in which the central region of the tumor was above the C-5 level; and lower tumor (L) group, in which the central region of the tumor was at or below the C-5 level. Changes in alignment of the cervical spine were measured on plain lateral radiographs. Data on atrophy of the deep extensor muscles (DEMs), tumor location, detachment of the DEMs from the C-2 spinous process, the C2–7 angle before surgery, patient age at surgery, tumor histology, patient sex, tumor size, and number of laminae affected were reviewed for each patient, and the correlation of each of these factors with cervical spinal malalignment was evaluated using statistical analysis.

RESULTS

The 54 adults eligible for analysis had a mean age of 49.1 years. Ependymoma was the most common cervical intramedullary tumor (63.0%) in this series. In the tumor location U group, the kyphotic angle of the C2–7 spinal segments increased after surgery (−5.8° ± 2.8°). In contrast, in the L group, the C2–7 lordotic angle increased after surgery (6.4° ± 2.6°). In the univariate analysis, atrophy of the DEMs, detachment of the DEMs from the C-2 spinous process, and an upper cervical location of the tumor were identified as factors significantly correlated with the development of cervical spinal kyphosis after surgery. Multiple linear regression analysis revealed the following as risk factors for kyphotic change of the cervical spine after surgery: 1) atrophy of the DEMs after surgery (β = −0.54, p < 0.01), and 2) detachment of the DEMs from the C-2 spinous process (β = −0.37, p < 0.01).

CONCLUSIONS

Atrophy of the DEMs after surgery and detachment of the DEMs from the C-2 spinous process are directly related to the risk of cervical spinal kyphosis after surgery for cervical intramedullary tumors in adults. Therefore, preservation of the DEMs, especially those attached to the C-2 spinous process, is important for the prevention of kyphotic malalignment of the cervical spine after surgery for intramedullary tumors.