Surgical Treatment of Cervical Spondylotic Amyotrophy Predicting Factor Related with Poor Outcome  Classification:  Spine  Keywords:  Cervical; Outcomes  Author(s):  Ryoji Tauchi, MD, Nagoya, Japan
Shiro Imagama, MD, Nagoya, Japan
Zenya Ito, Nagoya, Japan
Kei Ando, MD, Nagoya, Japan
Kenichi Hirano, MD, Nagoya, Japan
Akio Muramoto, Nagoya, Aichi, Japan
Hiroki Matsui, Nagoya, Japan
Naoki Ishiguro, MD, Nagoya, Japan
 Abstract:  INTRODUCTIONCervical spondylosis causes upper extremity muscle atrophy without sensory disturbance, which is called as cervical spondylotic amyotrophy (CSA). Since Keegan first reported autopsy case of this patient, there have been various reports regarding treatment strategies, diagnostic methods, conservative treatments, and surgical results for CSA, as well as the conditions of CSA. However, several questions associated with CSA still remain. In this study, we evaluate the predicting factors related with poor outcome after surgical treatment in CSA patients.
METHODSOf 27,807 registered patients who underwent spinal surgery between 1995 and December 2009, 57 underwent surgery for CSA, of whom 40 could be followed up for one year or longer, and they were evaluated. The subjects were 37 men and three women, with an average age of 59 years (39 to 78). The mean follow-up period was three years (1 year to 12 years and 9 months). To evaluate the surgical treatment effect, MMT (manual muscle test) was used, and improvements in the muscle strength of the most atrophic impaired muscle were classified in four grades. These were: “excellent,” full recovery; “good,” 1 grade of recovery by MMT; “fair,” no improvement by MMT; “poor,” worsening by MMT before surgery and at the time of the last follow up. The evaluation items included the duration of CSA, time needed for an improvement of at least 1 MMT grade postoperatively, whether the subjects had proximal- or distal-type CSA, ranges of spinal cord compression shown on cervical MRI, and surgical methods.
RESULTSThe duration of CSA was 6.8 months on average, 28 patients had proximal-type CSA, and 12 patients had distal-type CSA. The surgical results were: excellent for 22 patients, good for eight, fair for nine, and poor for one. Intramedullary signal intensity changes were confirmed in 13 of 38 subjects, and spinal cord compressions were found at an average of 2.8 intervertebral levels. In terms of the surgical method, laminoplasty with or without foraminotomy was performed for 31 patients, posterior fusion for four patients, and anterior spinal fusion for five patients. The time needed for a postoperative improvement of at least 1MMT grade was approximately five months. In comparison between patients rated as excellent or good and those rated as fair, the patients who had fair or poor outcome after surgery revealed that the duration of CSA was longer (284 vs. 176 days, respectively), preoperative MMT grades showed a tendency to be lower (grade: 1.8 vs. 2.5, respectively), and the proportion of distal-type CSA was higher in the poor outcome group. In addition, seven patients of poor outcome group underwent laminoplasty without foraminotomy, and the remaining two underwent posterior fusion.
DISCUSSION AND CONCLUSIONFrom these results, it was demonstrated that the duration of CSA was longer, and preoperative MMT grades showed a tendency to be lower in the patients with poor surgical outcome than in those with good outcome. Based on these results, early surgery is recommended for patients in whom a diagnosis of CSA has been made and conservative treatments have not been successful. On the subject about surgical methods, laminoplasty without foraminotomy was performed at a higher probability in those with poor results, and, hence, if the CSA patients present ventral nerve root impingement, appropriate foraminotomy should be performed in consideration of the decompression site based on imaging findings.