Key-words:
Anterior cervical discectomy - cervical spondylotic myelopathy - compressive myelopathy - T2 hyperintense signal - clinical outcome
Introduction
Degenerative cervical myelopathy represents the wide spectrum of age-related changes of the cervical spine that result in spinal cord injury and dysfunction.[[1]] Objective clinical assessment of myelopathy can demonstrate signs such as hyperreflexia, gait ataxia, Hoffmann's sign, and ankle clonus. While the diagnosis of cervical myelopathy is primarily based on clinical assessment, magnetic resonance imaging (MRI) is typically used to confirm the diagnosis where the static compression of the cord and hyperintensity may be the most likely appearance with increasing age.[[1]],[[2]],[[3]],[[4]]
Several reports have thought to assess the extent of spinal cord dysfunction and the potential for postoperative neurological recovery through the evaluation of spinal cord signal changes on T2-weighted (T2WI) and T1-weighted images (T1WI).[[5]],[[6]],[[7]],[[8]],[[9]],[[10]],[[11]],[[12]],[[13]] To address this knowledge gap, MRI studies were previously conducted and reported using the AOSpine cervical spondylotic myelopathy-North America prospective multicenter data.[[14]],[[15]]
Materials and Methods
A retrospective observational study was conducted from August 2014 to December 2016 in the Neurosurgery Department, Qena University Hospital, South Valley University. An informed signed consent was taken from all the patients and for the use of their data before enrolling them into the study after approval of the Ethical Committee of Faculty of Medicine, South Valley University. Twenty-five patients were enrolled in the study. The inclusion criteria were patients with a diagnosed degenerative cervical disc herniation associated with MRI T2 hyperintense signal surgically treated by ACD. Patients with a history of acute cervical trauma were excluded.
Clinical and radiographical analyses were performed for all these patients. Clinical evaluation included a detailed history as a regard of symptoms, and a complete neurological assessment of motor power, sensory deficits, bulk, and tone of all the limbs was evaluated preoperatively and postoperatively at 3, 6, and 12 months using Modified Japanese Orthopedic Association (MJOA). MRI of the cervical spine was done preoperatively and 3-month postoperatively and all patient images showed T2 hyperintensity preoperatively [[Figure 1]]. Score MJOA was done preoperatively and at 3, 6, and 12 months postoperatively and results were tabulated and diagrammatically represented.
Figure 1: Magnetic resonance imaging T2 sagittal image showing cervical disc prolapse C (5-6) associated with hyperintense cord signal (white arrow)
Statistical analysis
Statistical analysis was performed using SPSS software version 22.0.
Results
Twenty-five patients including 16 (64%) females and 9 (36%) males were included in the study, with their ages ranged from 26 years to 64 years; mean age was 46.89 ± 7.52 standard deviation (SD) in years. Clinically, the data of patient symptoms and signs were collected and analyzed according to MJOA score. The predominant symptom was neck pain 96% (n = 24, followed by difficult walking (spastic gait) and weakness 92% (n = 23), urge incontinence 52% (n = 13), and brachialgia 20% (n = 5). The most common presenting clinical signs were the myelopathic types, hyperreflexia 96% (n = 24), Babinski sign 88% (n = 22), spastic weakness 76% (n = 19), Hoffman sign 64% (n = 16), clonus (patellar or ankle sustained or illsustained) 44% (n = 11), and hyposthesia according to the affected level 20% (n = 5) [[Table 1]] and [[Figure 2]].
Table 1: Demographic and preoperative clinical data
Figure 2: Linegram showing preoperative clinical signs and symptoms
Postoperatively, 3 (12%) patients had worsened in the form of motor power deterioration and 14 (56%) patients have no improvement and remain as preoperative condition. The remaining 8 (32%) patients had a reported postoperative improvement. All of the twenty-five in the study were scored according to previous clinical data by MJOA score preoperatively and through follow-up visits at Qena university neurosurgery outpatient clinic at 3, 6, and 12 months and it showed slight clinical improvement as the mean MJOA score increased from 12.89 ± 1.39 (SD) preoperatively up to 13.79 ± 1.33 (SD) [[Table 2]] and [[Figure 3]].
Table 2: Modified Japanese Orthopedic Association score preoperatively and through 1-year postoperatively
Figure 3: Three-dimensional area chart demonstrating mean Modified Japanese Orthopedic Association score preoperatively, and through 1-year postoperatively, there is slight ascending increase in the curve denoting that there is slight postoperative clinical improvement after anterior cervical discectomy was done for cervical disc prolapse associated with magnetic resonance imaging T2 hyperintensity
Radiographically, cervical spine MRI was done preoperatively and 3-month postoperatively and all patient images showed T2 hyperintensity preoperatively [[Figure 4]]. Three-month postoperative MRI showed recovery of the cord signal in 19 (76%) patients while in the remaining six (24%) patients, the signal was present [[Figure 5]]. It was noted that nine patients out of 19 patients who showed radiographical recovery was not associated with clinical improvement.
Figure 4: T2-weighted images sagittal magnetic resonance imaging showing preoperative image (a) with C (3-4), C (4-5) Disc prolapse with hyperintense cord signal (white arrow) and 3-month postoperative image (b) with recovery of the signal
Figure 5: Three-dimensional columnar chart showing the 3-month postanterior cervical discectomy state for the cord signal recovery
Discussion
Demographic features of patients studied in preceding studies with moderate variability are shown in [[Table 3]]. In this study, we note that there were female majority in the studied cases where 25 patients were included in the study; 16 (64%) females and 9 (36%) males. Mean age was 46.89 ± 7.52 SD years with range from 26 to 64 years; it is a retrospective observational study and the follow-up duration was 12 months. This is not coincidental with the formentioned studies as there were male majority and most of studies were of a prospective type.
Table 3: Demographic data in preceding studies in relation to this study
Clinically, symptoms and signs of patients were documented and analyzed according to variable outcome scores such as Nurick score, Ranawat scale, Japanese orthopedic association score, MJOA score, and neck disability index. These scores were used variably from one study to another. MJOA Score is the most common scale used to record the neurological status as shown in [[Table 4]].[[23]]
Table 4: Types of scores used by different studies
T2W increased signal intensity (ISI) was associated with worse surgical functional outcomes. The sharp, intense, well-circumscribed ISI was associated with poorer functional status at follow-up.[[26]],[[27]],[[28]],[[29]],[[30]] Patients who had postoperative better results are those patients without T2W ISI or with postoperative regression of ISI.[[20]],[[30]],[[31]],[[32]] In our study, postoperatively, 3 (12%) patients had worsened in the form of motor power deterioration, 14 (56%) patients has no improvement and remain as preoperative condition, and the remaining 8 (32%) patients had a reported postoperative improvement. All of the twenty-five in the study were scored according to previous clinical data by MJOA score preoperatively and through follow-up visits at 3, 6, and 12 months and it showed very slight clinical improvement as the mean MJOA score increased from 12.89 ± 1.39 (SD) preoperatively up to 13.79 ± 1.33 (SD) at the end of 1-year postoperatively.
It has been suggested that tracking changes in T2W ISI after decompressive surgery could predict long-term functional outcome. Mehalic et al. were one of the first to provide evidence for this relationship.[[19]] Many studies concluded that complete or partial regression of T2W ISI postoperatively was associated with better outcomes when compared with patients who had no change in ISI after surgery.[[18]],[[22]],[[33]] Arvin et al. showed that an improvement in the grade of T2W ISI at 6-month postoperatively predicted better functional status at 1 year after surgery, and regression of ISI after surgery is associated with a higher probability of functional recovery.[[17]] In this study, 3-month postoperative MRI showed recovery of the cord hyperintense signal in 19 (76%) patients, while in the remaining 6 (24%) patients, the signal was present. It was noted that 9 patients out of 19 patients who showed radiographical recovery were not associated with clinical improvement and this is quietly similar to the overmentioned studies.
Conclusion
The presence of T2W hyperintense signal on preoperative MRI predicts a poor surgical outcome in patients with cervical disc prolapse. The regression of T2W ISI postoperatively correlates with better functional outcomes.
