| | Effect of intramedullary signal changes on the surgical outcome of patients with cervical spondylotic myelopathy☆☆☆Received 27 February 2002; accepted 15 May 2002. Abstract Background context: Intramedullary signal intensity changes on magnetic resonance imaging (MRI) in cervical spondylotic myelopathy are thought to be indicative of the prognosis. However, the prognostic significance of signal intensity changes remains controversial. Purpose: To determine the radiographic and clinical factors that correlate with the prognosis after surgery in patients with cervical spondylotic myelopathy and to investigate the factors affecting the outcome of intramedullary signal changes on MRI. Study design: A prospective study evaluating clinical parameters and MRI in consecutive patients operated on for cervical spondylotic myelopathy. Patient sample: A total of 146 consecutive patients with cervical spondylotic myelopathy operated on during a 2-year period (September 1999 to September 2001) formed the study group. Outcome measures: Age, duration of symptoms, number of cervical prolapsed intervertebral discs, surgical approach, preoperative signal changes, residual compression and postoperative outcome of signal changes; clinical outcome (motor, sensory, autonomic and disability improvement). Methods: The participants in this study underwent anterior cervical discectomy/corpectomy or laminectomy/laminoplasty for cervical spondylotic myelopathy. Clinical features and MRI findings were studied in detail and compared with postoperative clinical and radiological status. The spinal cord signal intensity changes were evaluated before and after surgery. The multifactorial effect of such variables as age, duration of symptoms, number of prolapsed intervertebral discs, surgical approach (anterior/posterior), preoperative cord changes on T1- and T2-weighted sequences and persistence/regression of cord changes on clinical outcome (motor/sensory/autonomic/disability improvement) was studied using stepwise logistic regression. The highlight of the study is the analysis of the factors affecting regression of cord changes and their effect on postoperative outcome. Results: Preoperative intramedullary signal changes were present in 121 of 146 patients (82.9%); of these 121 patients, T1- and T2-weighted images were present in 81, and T2-weighted images were present in 40 (no patient had isolated T1 change). Postoperative MRI could be obtained in 44 of 121 patients (36.4%) with preoperative intramedullary signal changes; 14 had regression of cord changes. There was no significant difference in the clinical presentation of patients with and without cord changes. There was a significant correlation between the surgical outcome of patients and their age, duration of symptoms, number of cervical prolapsed intervertebral discs, surgical approach, preoperative signal changes, residual compression and postoperative outcome of signal changes. The patients with no intramedullary signal changes and signal changes only on T2-weighted images had a better outcome than patients with signal changes on both T1- and T2-weighted images. The patients with regression of intramedullary signal changes had significantly better outcome. There was no significant correlation between regression of signal changes and other factors. However, chronicity of disease, multiplicity of discs and postoperative residual compression relatively affect persistence of intramedullary signal changes. Conclusions: The presence of intramedullary signal changes on T1- as well as T2-weighted sequences on MRI in patients with cervical spondylotic myelopathy indicates a poor prognosis. However, the T2 signal intensity changes reflect a broad spectrum of spinal cord reparative potentials. Predictors of surgical outcomes are preoperative signal intensity change patterns of the spinal cord and their postoperative persistence/regression on radiological evaluations, age at the time of surgery, multiplicity of involvement and chronicity of the disease and surgical approach (anterior/posterior).
Introduction  Cervical spondylosis is widespread in all cross sections of the adult population; it has been estimated that 50% of the population over the age of 50 years and 75% over the age of 65 years have the disease [1]. It is indeed fortunate that only a small proportion develop the most serious complication of the disease, namely, cervical spondylotic myelopathy (CSM). CSM can lead to devastating and crippling neurological deficits 2, 3. The mainstay of diagnosis is clinical evaluation and imaging by plain radiographs (X-ray) and magnetic resonance imaging (MRI). MRI with recent technical developments has become an indispensable technique for the diagnosis [4]. The signal intensity changes of the spinal cord on MRI in CSM are thought to reflect pathological changes in the spinal cord and to be indicative of the prognosis [4]. However, the significance of the signal intensity change for prognostic values has been controversial [5]. The present study has been prospectively designed to investigate which MRI findings in patients with CSM reflect the clinical presentation and prognosis, and to determine the radiographic and clinical factors that correlate with the postoperative outcome in these patients. Previous studies in the literature are all retrospective in nature and suggest a correlation between the clinical and radiological outcome in patients with CSM 6, 7, 8, 9, 10. The outcome in patients with intramedullary signal intensity changes was worse than in patients with no signal changes on the preoperative MRI 6, 7, 8, 9, 10. They observed that regression of cord changes on T2-weighted images correlated with better postoperative outcome than patients with persistence of signal intensity changes 7, 8, 9, 10. Ours is the first prospective study in the existing literature focused not only on high-signal intensity changes in the compressed spinal cord on T2-weighted images, but also on low signal intensity changes on T1-weighted images. Materials and methods A prospective study was conducted on 146 patients with CSM operated on in our department from September 1999 to September 2001. The clinical parameters and radiological findings of all patients were evaluated and recorded in detail. The age, gender, duration and intensity of symptoms and deficits, and the disability status at the time of presentation were recorded. The patients were graded for their functional disability on the basis of the Nurick [11] grading system. MRI of the cervical spine was done as a preoperative investigation in all the cases. A 1 T or 1.5 T superconducting imaging system was used for the MRI. Using a spin echo sequence system, T1- and T2-weighted images of axial and sagittal views of the cervical spinal cord were obtained. The level of compression and the presence of anterior or posterior compression were noted. The presence or absence of intramedullary signal changes (ISCs) on T1- and T2-weighted images was noted. The clinical condition and functional grade of the patients with and without cord changes were compared. After detailed clinical, functional and radiological evaluation, the patients were subjected to the surgery: anterior cervical discectomy 12, 13, corpectomy, laminectomy, laminoplasty. Postoperatively, the patients were assessed clinically and by the Nurick grading system at 3- and 6-month follow-up in an outpatient clinic. Postoperative MRI was obtained in the patients with preoperative cord changes (44 of 121 patients, 36.4%). Postoperative MRI was evaluated for the presence/absence of residual compression and persistence/regression of cord changes on T1- and T2-weighted sequences compared with preoperative MRI. The multifactorial effect of such variables as age, duration of symptoms, number of prolapsed intervertebral discs (PIVDs), surgical approach (anterior/posterior), preoperative cord changes on T1- and /T2-weighted images and persistence/regression of cord changes on the clinical outcome (motor/sensory/autonomic/disability improvement) was studied. The highlight of the study was the analysis of the factors affecting regression of cord changes and their effect on postoperative outcome. Statistical analysis The data recorded on predesigned proforma were managed on Microsoft Excel software. Data entry was double-checked for any human error. Statistical analysis using Intercooled STATA version 5.0 (Stata Corporation, College Station, TX) was used. Association between the outcome variable and other categorical variables was assessed by the chi-squared test. Any association having p<.05 was considered as statistically significant. At the second stage of analysis, the associations were quantified by unadjusted odds ratios (ORs) and 95% confidence interval (CI). Variables showing statistically significant association at p<.20 were considered as candidate predictors. In the third stage, stepwise logistic regression was applied to determine a cost-efficient model from the candidate variables identified in the second stage. Results A total of 146 consecutive patients with CSM operated on during a 2-year period (September 1999 to September 2001) formed the study group. The ages ranged from 17 to 76 years (mean age, 47.1 years), and there was a male predominance (116, 79.5%). Nearly 60% of the patients were in the fourth and fifth decades (31 to 40 years, 26.7%; 41 to 50 years, 33.6%). The duration of symptoms ranged from 1.5 months to 10 years (mean, 11.7 months). The majority of the patients presented 6 to 12 months (54, 37%) after their onset of symptoms, followed by less than 6 months and 13 to 24 months (32, 21.9% each). The most common presenting motor symptom was weakness (129, 88.4%) followed by spasticity (115, 78.8%). Associated wasting was seen in 43 patients (29.5%), flexor spasms in 20 (13.7%) and fasciculations in 19 (13%). Sensory loss was present in 114 patients (78%) and associated radicular symptoms (upper extermity) in 126 (86.3%). Paraesthesias were present in 90 patients (61.6%). Autonomic symptoms were present in 56 patients (38.4%), the most common being bladder involvement (45) followed by bowel involvement (5) and both bowel and bladder involvement (6). Six male patients had associated impotence. Preoperative functional disability was evaluated by the Nurick grading system: Grade 1, 5 (3.4%); Grade 2, 30 (20.5%); Grade 3, 61 (41.8%); Grade 4, 32 (21.9%) and Grade 5, 18 (12.4%). Preoperative MRI revealed anterior compression in 123 (84.2%), posterior compression in 18 (12.3%) and both anterior and posterior compression in 5 (3.5%). The most common PIVD was at the C5–C6 level (91, 41.7%) followed by C4–C5 (60, 27.5%), C6–C7 (36, 16.6%), C3–C4 (28, 12.8%) and C2–C3 (3, 1.4%). There were 61 patients (41.8%) with two-level PIVD, 41 patients (28.1%) with single-level PIVD and 44 patients (30.1%) with three or more levels of PIVD. In the study group, 121 patients (82.9%) had ISCs and 25 patients (17.1%) did not have ISCs on the preoperative MRI. Among the 121 patients with ISCs, 81 patients (66.9%) had ISCs both on T1- and T2-weighted images and 40 (33.1%) had ISCs on only T2-weighted images. All patients with ISCs on T1-weighted images had changes on T2-weighted images. There was no patient with isolated ISCs on T1-weighted images (ISCs on T1-weighted images=hypointensity on T1-weighted images; ISCs on T2-weighted images=hyperintensity on T2-weighted images; Table 1). There was no statistical difference in the age, gender, duration of symptoms, clinical presentation and functional disability in the patients with ISCs compared with the patients without ISCs on the preoperative MRI. However, the incidence of fasciculations (19% with ISCs and 8% without ISCs) and paraesthesias (76% with ISCs and 48% without ISCs) was more common in patients with ISCs. although they were not statistically significant (Table 1). A total of 121 patients (82.9%) were operated on by the anterior approach and 25 patients (17.1%) by the posterior approach. Among the patients operated on by the anterior approach, most common was two-level discectomy (61% to 41.8%) followed by single-level discectomy (41% to 28.1%) and three or more levels of discectomy (19% to 13.0%). Twelve patients underwent corpectomy. All patients except two underwent interbody fusion (tricorticate iliac bone graft, 86 after discectomy and 12 after corpectomy; dowel iliac bone graft, 3; polymethylmethacrylate graft, 1; hydroxyapatite graft, 17). Four patients after three or more levels of discectomy and eight patients after corpectomy underwent anterior cervical locking plate fixation. In the patients operated on by the posterior approach, there were 19 laminoplasties and 6 laminectomies. Postoperative MRI was obtained in 44 of 121 patients (36.4%) with ISCs on preoperative MRI. Our follow-up magnetic resonance images were relatively few in number, because a majority of our patients belonged to the poor socioeconomic strata; postoperative MRI after three months was not economically feasible for all. Thirty-one patients (70.4%) had no residual compression, 8 (18.2%) had Grade II compression with cerebrospinal fluid (CSF) indentation with no compression on the cord (CSF displaced but seen around the cord), and 5 (11.4%) had Grade III compression with indentation of the cord. Regression in ISCs on T1-weighted images was seen in 7 of 34 patients (20.6%) and T2-weighted images in 14 of 44 (31.8%). In 30 patients (68.2%) ISCs were the same as those seen on the preoperative MRI (Table 2). Correlation among predictors of postoperative outcome Motor outcome In the study group, 103 patients (70.3%) had postoperative improvement in motor symptoms. The patients in the younger age group (age, younger than 40 years) had significantly better outcome (p<.05, OR=2.9, 95% CI=.7 to 4.2). The patients with less than a 1-year duration of symptoms showed significantly more improvement than patients with a longer duration of symptoms (p<.05, OR = 5.9, 95% CI=0.82 to 12.5). Patients operated on by the anterior approach had better outcome than the patients operated on by the posterior approach (p<.005, OR=2.95, 95% CI=0.4 to 11.2). Patients having three or more levels of PIVDs had a poorer outcome than patients with single- or two-level PIVDs (OR=0.72, 95% CI=0.22 to 1.32). Patients without ISCs on preoperative MRI had significantly better outcome than patients with ISCs on T1- and T2-weighted images (p<.001, OR=5.1, 95% CI=1.87 to 25.1). However, there was no significant difference in the outcome of patients without ISCs compared with patients with ISCs on only T2-weighted images preoperatively. Patients with ISCs on only T2-weighted images had significantly more improvement compared with the patients with ISCs on both T1- and T2-weighted images (p<.05; OR=2.9, 95% CI=1.4 to 9.19). Patients with no compression on postoperative MRI had better outcome than patients with residual compression (p<.05, OR=2.95, 95% CI=1.0 to 9.6). Among the patients showing regression of ISCs, 92.9% had improvement in motor symptoms compared with 63.3% improvement among the patients with no regression. The difference in improvement in two groups was statistically significant (p<.05, OR=11.66, 95% CI=1.06 to 128.11; Table 3). Sensory outcome The sensory symptoms improved in 92 of 115 patients (80%). There was no significant effect of age, duration of symptoms, number of PIVDs and preoperative ISCs on postoperative sensory improvement. Patients operated on by the anterior approach had better outcome than those operated on by the posterior approach (p<.05, OR=2.9, 95% CI=0.5 to 8.5). Patients with no compression on postoperative MRI had better outcome (p<.01, OR=3.9, 95% CI= 0.5 to 27). Among the patients with regression of ISCs, 92.9% of patients had improvement in sensory symptoms compared with 68.9% improvement in patients with no regression (OR=3.2, 95% CI=0.7 to 11.4). Autonomic outcome In the study group, 35 of 56 patients (62.5%) showed improvement in autonomic symptoms. Patients with no residual compression on postoperative MRI had better outcome (p<.005, OR=3.61, 95% CI=0.23 to 13.4). All patients with regression of ISCs showed improvement, whereas in patients who did not show regression, improvement was seen in 63.6% of patients (OR=1.6, 95% CI=0.3 to 5.61). There was no significant effect of age, duration of symptoms, number of PIVDs, surgical approach and preoperative ISCs on the postoperative autonomic improvement. Disability outcome Preoperatively, 5 patients (3.4%) were Nurick Grade I, 30 (20.5%) Grade II, 61 (41.8%) Grade III, 32 (21.9%) Grade IV and 18 (12.4%) Grade V. Postoperatively, 26 patients (17.8%) were Grade I, 62 (42.5%) Grade II, 26 (17.8%) Grade III, 24 (16.4%) Grade IV and 8 (5.5%) Grade V. Patients in the younger age group (younger than 40 years) had significantly more improvement in their disability status (p<.001, OR=2.17, 95% CI=0.61 to 9.1). Patients with more than a 2-year duration of symptoms had significantly poorer outcome after surgery (p<.05, OR= 0.68, 95% CI=0.30 to 1.54). Patients with single- (p<.001, OR=2.91, 95%CI=0.7 to 10.4) or two-level (p<.001, OR=2.61, 95% CI=0.4 to 8.9) had better outcome than multiple-level PIVD. Improvement in disability status was seen in 66.9% of patients operated on by the anterior approach and in 24% of patients operated on by the posterior approach (p<.001, OR=7.15, 95% CI=1.8 to 17). There was no significant difference in the outcome of patients without ISCs compared with patients with ISCs on T2-weighted images. However, the postoperative outcome of the patients without ISCs was relatively better than the ones with ISCs on both T1- and T2-weighted images (OR=1.98, 95% CI=1.79 to 7.61). The outcome of the patients with ISCs on only T2-weighted images was better than the outcome of patients with ISCs on both T1- and T2-weighted images (p<.05, OR=3.2, 95% CI=1.2 to 16). Patients with no compression on postoperative MRI had better outcome (p<.05, OR=7.14, 95% CI=1.8 to 13.1). In patients with regression of ISCs, 85.7% of the patients had improvement compared with 53.3% in patients with no regression (p<.05, OR=2.98, 95% CI=0.5 to 9.5; Table 4). Factors affecting ISCs There was no significant effect of age, duration of symptoms, level of discs, surgical approach and preoperative disability on persistence/regression of ISCs (p=not significant). Because the size of the sample of patients with regression of ISCs in T2-weighted images and T1- plus T2-weighted images was small, only a relative role of the factors affecting the regression of ISCs can be established. None of the patients with more than 2-year duration of symptoms and postoperative residual compression showed regression of ISCs. Patients with three or more levels of PIVD have relatively fewer chances of regression of ISCs (OR=0.2, 95%CI=0.02 to 3.2). Therefore, chronicity of disease, multiplicity of discs and postoperative residual compression are relative factors affecting persistence of ISCs (Table 5).
1.Group A: patients with regression of ISCs on T1-weighted images (n=7). In patients who had regression of ISCs on T1-weighted images (n=7), all the patients showed improvement in motor and autonomic symptoms. The improvement in sensory symptoms and Nurick grade was seen in six of the seven patients (Table 6, Table 7; Fig. 1, Fig. 2). | | |  | | Number (%) | |
|---|
| T1-weighted images regressed (n=7) | | |
| Motor improvement | 7/7 (100) | |
| Sensory improvement | 6/7 (85.7) | |
| Autonomic improvement | 2/2 (100) | |
| Disability improvement | 6/7 (85.7) | |
| T1-weighted images (n=27) | | |
| Motor improvement | 17/27 (62.9) | |
| Sensory improvement | 10/21 (47.6) | |
| Autonomic improvement | 10/14 (71.4) | |
| Disability improvement | 15/27 (55.6) | |
| T2-weighted images regressed (n=14) | | |
| Motor improvement | 13/14 (92.9) | |
| Sensory improvement | 13/14 (92.9) | |
| Autonomic improvement | 9/9 (100) | |
| Disability improvement | 12/14 (85.7) | |
| T2-weighted images same (n=30) | | |
| Motor improvement | 19/30 (63.3) | |
| Sensory improvement | 20/29 (68.9) | |
| Autonomic improvement | 14/22 (63.6) | |
| Disability improvement | 16/30 (53.3) | | | | |
2.Group B: patients with persistence of ISCs on T1-weighted images (n=27). In this group motor improvement was recorded in 17 of 27 patients (62.9%), sensory improvement in 10 of 21 (47.6%), autonomic improvement in 10 of 14 (71.4%) and disability improvement in 15 of 27 patients (55.6%). The improvement was significantly higher in Group A than in Group B (p<.001; Table 6, Table 7; Fig. 3).
3.Group C: patients with regression of ISCs on T2-weighted images (n=14): The improvement in motor and sensory symptoms was observed in 13 of 14 patients (92.9%). Autonomic symptoms improved in all the patients (9 of 9) in this group. Nurick grade improved in 12 of 14 patients (85.7%) (Table 6, Table 7; Fig. 4).
4.Group D: Patients with persistence of ISCs on T2-weighted images (n=30). In this group motor symptoms improved in 19 of 30 patients (63.3%), sensory symptoms in 20 of 29 (68.9%) and autonomic symptoms in 14 of 22 (63.6%). The improvement in Nurick grade was seen in 16 of 30 patients (53.3%). The improvement was significantly higher in Group C than in Group D. (p<.01; Table 6, Table 7).
◦Two patients showed complete resolution of ISCs on postoperative MRI. Both these patients had symptoms of less than 1 year's duration and had improvement in motor, sensory and autonomic deficits and functional disability (Table 7).]
Discussion A comparison of published studies on CSM is difficult for many reasons; the clinical materials lack uniformity, the surgical techniques vary and the criteria for assessment vary. The unifying concept in CSM is that of spinal cord ischemia and compression [3]. The original experiments of Wilson and Campbell [14], Chakarvorty [15], Hoff et al. [16] and more recently Al-Mefty and Harkey [17] support the argument that compromise of parenchymal blood flow compounds the effect of compression. Radiological and histopathological correlation of ISCs The significance of ISCs as a prognostic factor of the outcome of CSM has been controversial. It has been speculated that a change in the signal intensity of the spinal cord observed on MRI 4, 5, 7, 8 reflects pathological changes in the spinal cord according to the autopsy studies of the pre-MRI period 14, 15, 16 in patients with CSM. Takahashi et al. [7] considered that a high signal intensity change of the spinal cord reflected myelomalacia or cord gliosis secondary to long-standing compression of the spinal cord. Mehalic et al. [8] concluded that high signal changes on T2-weighted images were nonspecific and indicated edema, inflammation, vascular ischemia, gliosis or myelomalacia. Ramanausakas et al. [5] divided myelomalacia into three stages: early, intermediate and late. A change in signal intensity of the spinal cord observed on MRI reflected cord edema in the early stage and cystic necrosis of the central gray matter after prolonged cord edema in the late stage. They also stated that in the early and intermediate stages, the spinal cord showed a high signal intensity on T2-weighted images and that in the late stage, a low signal intensity on T1-weighted images and a high signal intensity on T2-weighted images were noted [5]. Al-Mefty et al. [4] reported that a high signal intensity on T2-weighted images reflected myelomalacia and that low signal changes on T1-weighted images with high signal changes on T2-weighted images indicated cystic necrosis or secondary syrinx. There are a few experimental studies on the interrelations between the ISCs on the MRI and the actual histopathological background 18, 19. Al-Mefty et al. [18] reported that intramedullary changes of the spinal cord on MRI coincided with pathological changes in the gray matter of the spinal cord, which included loss of motor neurons, necrosis and cavitation in experimental chronic compressive myelopathies of canines. Ohshiro et al. [19] discussed the correlation between the MRI and histopathology of the diseased spinal cord in the autopsies of humans. They concluded that the signal pattern of T1 hypointensity/T2 hyperintensity changes indicated necrosis, myelomalacia and spongiform change in the gray matter, and that the signal pattern of T1 isointensity/T2 hyperintensity changes indicated edema, gliosis and a slight loss of nerve cells in the gray matter [19]. Clinical significance of ISCs Morio et al. [9] found significant correlation between the age at presentation and neurological improvement. In the present study as well, there was significant correlation between the age at presentation and the clinical outcome of patients. Patients in the younger age group (age younger than 40 years) and those with symptoms of less than 1 year's duration had significantly better outcome of motor symptoms and disability status. In the studies by Matsuda et al. [6] and Morio et al. [9] there was significant correlation between the duration of symptoms and the clinical outcome of patients. Mehalic et al. [8] in their study of 19 patients did not find any significant correlation between the duration of symptoms and the outcome. In the present study, the improvement in motor symptoms and disability was significantly higher in the patients without signal changes and patients with cord changes on T2-weighted images compared with the patients with signal intensity changes both on T1- and T2-weighted images. Takahashi et al. [7] observed in their study that patients without signal intensity changes fared better in both the surgical and conservative treatment groups. In patients with decompression surgery, good improvement was seen in 8 of 18 patients (44.4%) with high signal intensity changes and 11 of 13 patients (84.6%) without signal changes. In patients with conservative management, improvement was observed in 16 of 40 patients (40%) with high signal intensity changes and in 31 of 48 (64.6%) without signal changes. In a study by Matsuda et al. [6], increased signal intensity on T2-weighted images was seen in 12 of the 29 patients. In these patients, outcome was worse than in patients with no signal changes on the preoperative MRI, and patients with high signal intensity that decreased after surgery showed a better recovery rate after surgery than those in whom the high signal increased or did not change. Mehalic et al. [8], Morio et al. [9] and Takahashi et al. 7, 10 also observed that regression of ISCs on T2-weighted images correlated with better postoperative outcome than patients with persistence of ISCs. Mehalic et al. [8] presented a series of 19 patients with CSM and assessed their MRIs before and after surgery. They reported that the patients showing an improvement in clinical symptoms after surgery demonstrated a postoperative decrease in high signal intensity on T2-weighted images. He therefore suggested a correlation between the clinical and radiological improvement of those patients. In contrast, Matsumato et al. [20] and others 21, 22, 23, 24 concluded that the altered signal intensity on T2-weighted images was not related to the poor outcome. However, Ratliff and Voorhies [25] reported a case in which there was complete resolution of cord changes on postoperative MRI, although clinical improvement did not parallel radiographic resolutions. However, the earlier studies did not take into consideration altered signal intensity pattern on T1-weighted images. Morio et al. [9] observed that patients with altered signal intensity on both T1- and T2-weighted images had a relatively poor outcome compared with the patients with signal changes only on T2-weighted images. However, their study was retrospective and contained only four patients with hypointensity T1-weighted images/hyperintensity T2-weighted images. In the present study as well, the patients with ISCs who showed regression on T1- and T2-weighted images showed significantly higher recovery rate than did patients in whom the cord changes were unchanged postoperatively. Therefore, the high signal changes on T2-weighted images indicated both pathologically reversible and irreversible changes in the spinal cord, and the low signal intensity changes on T1 WI were considered to reflect pathologically irreversible changes. We speculate that the high signal changes on T2-weighted images on magnetic resonance images include a broad spectrum of compressive myelomalacic pathology from edema to syrinx formation and reflect a broad spectrum of spinal cord reparative potentials. However, the regression pattern of ISCs in patients with hypointensity T1-weighted images/hyperintensity T2-weighted images lead us to speculate that there may be a pattern of relatively recent or chronic onset of such changes that can be delineated by determining the enhancement characteristics by administration of gadolinium 26, 27. In the present study, there was no significant correlation between the regression of cord changes with various other variables. However, it could be postulated that the chronicity of disease, multiplicity of discs and postoperative residual compression are relative factors affecting persistence of cord changes. Predictors of surgical outcome Regarding predictors of surgical outcome, the age at the time of presentation [28], the chronicity of myelopathic symptoms 28, 29, 30, 31, 32, 33, the multiplicity of involvement 28, 33, the signal changes on preoperative MRI 6, 7, 8, 9, 10 and their regression/persistence 6, 7, 8, 9, 10 have been considered to be the key predictors. All these factors had a significant impact on the outcome of the patients in the present study as well. Patients operated on by the anterior approach had a relatively better disability, motor and sensory outcome than those operated on by the posterior approach. However, the correlation is weak because of the disparity in the size of the two groups. Preoperative transverse area of the spinal cord at the site of maximal compression has been observed to be a predictor of surgical outcome 28, 30, 32, 33. However, Morio et al. [9] concluded that although it is a key factor in myelopathic symptoms, it is not a predictable parameter. However, it would be worthwhile to extend the study in order to obtain a higher follow-up imaging (MRI) and a longer clinical and radiological follow-up (1 to 2 years) to observe the temporal effect of outcome. It would also be interesting to compare patients with less severe clinical syndromes who have undergone surgery with those treated nonoperatively. Cross-sectional area of the white matter changes have not been studied in detail in the existing literature. However, assessment of the volume of the white matter changes by future software technology would be important in objective evaluation of the persistence/regression of the ISCs. Conclusions
•There was no significant difference in the clinical presentation of patients with or without ISCs.
•There was significant correlation between age, duration of symptoms, number of PIVDs, preoperative ISCs, residual compression and postoperative regression/persistence of ISCs and the surgical outcome.
•The patients without ISCs and ISCs on only T2-weighted images had a better outcome than patients with ISCs on both T1- and T2-weighted images, that is, hypointensity T1/hyperintensity T2=poor prognosis, isointensity T1/hyperintensity T2=broad spectrum of spinal cord reparative potentials.
•There was no significant correlation between clinical and radiographic variables with regression of ISCs. However, chronicity of disease, multiplicity of discs and postoperative residual compression are relative factors affecting persistence of ISCs.
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a Departments of Neurosurgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India b Departments of Neuroradiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India c Departments of Biostatistics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India  Corresponding author. 34 Ganga Apartments, Alaknanda, Kalkaji, New Delhi 110019, India. Tel.: 91-11-6593291; fax: 91-11-6862663.
☆ FDA device/drug status: not applicable. ☆☆ Nothing of value received from a commercial entity related to this research. PII: S1529-9430(02)00448-5 © 2003 Elsevier Science Inc. All rights reserved. | |
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