Introduction

Multilevel compressive cervical myelopathy is the commonest cause of spinal cord impairment in the elderly population [1]. It comprises cervical spondylotic myelopathy (CSM), ossification of the posterior longitudinal ligament (OPLL), ossification of the ligamentum flavum (OLF), and degenerative disc disease (DDD). These structural changes, narrows the spinal canal and reduces the space available for the spinal cord, leading to neurological deficit. Surgical decompression is the gold standard procedure for preventing the progression of neurological deficits in these patients [2,3].

Good surgical results can be obtained by various surgical procedures done either anterior or posterior, such as anterior corpectomy and fusion, laminectomy alone or laminoplasty and laminectomy with fusion (LF). Patients with less than 3 segments involved can be managed by anterior surgeries, whereas when the involvement is more than 3 segments, posterior surgery is the gold standard [4].

The long-term efficacy of cervical laminectomy is already described in literature in past, but long-term follow-up data in Indian subcontinent is scanty. Here we are presenting long term outcome of microscopic posterior cervical laminectomy for multilevel compressive cervical myelopathy, with respect to functional recovery, complications and radiological outcomes.

Materials and methods

After ethical committee approval, we retrospective analyzed 118 patients (8 lost to follow-up) with multilevel compressive cervical myelopathy who underwent microscopic posterior cervical laminectomy in a single hospital by a single surgeon from January 2007 to December 2014. Preoperatively all the patients had signs and symptoms of long tract involvement, such as hand clumsiness, gait disturbance, and hyperreflexia in lower limbs. Patients with age ≥45 years, compression at 3 or more levels, C2-C7 cobb’s angle ≥ 10º (lordotic) and a minimum of 5 years’ follow-up after microscopic posterior cervical laminectomy were included in the study.

Patients with only axial neck pain without myelopathy, instability on dynamic x-ray’s, fracture/infection/metabolic disorders, revision surgery or having developmentally narrow spinal canal were excluded from the study. Demographic data (age, sex, duration of illness to presentation, and co-morbidities), pre‑ and post‑operative clinical parameters (neck pain score ‑ visual analogue scale [VAS], Nurick’s grading and modified Japanese orthopaedic association [mJOA]), radiological parameters (Sagittal cervical Cobb’s Angle),

Figure 1:Positioning of the patient in well-padded bolsters, arms by the side strapped and head secured.

Results

118 patients fulfilled the inclusion criteria, out of whom 8 patients were lost to follow up and hence 110 patients were included in the study. Out of 110 patients 63 had degenerative cervical spondylotic myelopathy (CSM) and 47 had cervical OPLL. The mean age of the patients was 55.6 years (range 44 to 74 years) with Male to female ration of 68:42.

The mean duration of presentation of illness was 3.2 months (range 1 to 8 months) and the mean duration of follow-up period was 7.6 years (range 5 to 11 years). 48 patients had ≥ 2 comorbidities, 44 had < 2 and 18 had no associated comorbidities. 21 patients were non-ambulatory at the time of presentation (table 1).

The mean blood loss was 95.9 ml (range 70 to 180 ml) and the mean operative time was 95.6 mins (range 82 to 140 min). The mean duration of hospital stay was 4.8 days (range 3 to 8 days) (table 2). VAS demonstrated significant improvement (p<0.05) from pre-op 3.7±1.5 to post-op 1.9±0.8.

There was significant difference (p<0.05) in Nurick’s grading preop 3.3±0.9 to post op 1.8±0.6. mJOA score improved from pre-op 8.3±1.4 to post-op 13.9±1.8 (p<0.05) (Table 3) the mean recovery rate at final follow-up was 57.7%. Out of 110 patients 21 (19%) had an excellent outcome, 43 (39%) had good, 37 (33.6%) had fair and 9 (8.1%) patients had a poor outcome (table 3).

Out of 110, 68 (61.8%) patients maintained cervical lordosis, 24 (21.8%) changes to a straight spine and 18 (16.3%) became kyphotic (kyphosis greater than +5°, straight from -5º to +5°, lordosis less than -5º) (table 3).

Intraoperatively 7 (6.3%) patients had a dural tear, although no repair was done intraoperatively, as the tear was small. There was no case of post-operative CSF leak.

Superficial infection developed in 6 (5.4%) individuals for which intravenous antibiotics were given till the healing and there was no case of deep infection or wound dehiscence.

Table 1: Demographics

Discussion

Surgical decompression is the gold standard treatment for multilevel cervical compressive myelopathy. Various techniques include anterior, posterior or combined approach [6].

The disadvantages associated with anterior approach are increased blood loss and surgical time, post-operative dysphagia, hematoma formation and fusion‑related complications [4,7-9]. Studies have shown that in general elderly patients have higher mortality, postoperative complications, and bony nonunion rates than younger patients [7,8].

Puvanesarajah et al demonstrated significantly increased rates of surgical complications and mortality after anterior cervical fusion [9]. Posterior decompression (laminectomy) with or without fusion are reliable and effective in treating multilevel cases [10].

Table 2: Perioperative parameters

Table 3: Clinical and radiological outcomes:

The incidence of kyphotic change after multi-level laminectomy is approximately 20% [11].

The mean recovery rate in present study at final follow-up was 57.7% which is more than the study done Kato et al [12] where at last evaluation it was 32.8% and comparable to Lee et al [14] study with a recovery rate of 56.3%. We observed that history of trauma, high BMI, a low preoperative mJOA score and late presentation were associated with a delayed recovery while higher preoperative JOA score and younger age at surgery were associated with early recovery.

Progression of OPLL was seen in 65.4% of the cases without any delayed neurological deficit, which is lesser than suggested by Hori et al [15] (in 71% at 10 years) and more than suggested by Chiba et al [16] where it was 56.5% of patients after 2 years.

The risk of durotomy during laminectomy is 0.3%–13% and can be up to 18% with revision surgery [17]. Singhatanadgige et al found the incidence of C5 palsy was higher 9.6%–25% following laminoplasty with fusion compared to 0%–8% in laminoplasty group [18]. Lee et al observed 5.9% C5 palsy in his study [14]. In our study the incidence of C5 palsy was 3.6% which recovered spontaneously within 6 months’ period. Axial neck pain may be the most frequently reported complication of laminectomy, with reports of its incidence ranging anywhere from 16%–48%.

We observed 21.9% incidence of axial neck pain which was manageable with medications. Bartels et al in his clinical randomized trial did not find a difference in the neurologic outcome or quality of life between laminectomy alone and laminectomy fusion groups at an average follow‑up of 18.3 months which suggest that laminectomy alone may be safe and effective in patients with preserved cervical lordosis and a stable cervical spine, without preoperative spinal instability [19].

As per our results and understanding we suggest microscopic posterior cervical laminectomy for patients with compressive cervical myelopathy ≥3 levels, without instability and C2-C7 cobb’s angle >10°.

Complications associated with fixation like higher incidences of C5 palsy, pseudoarthrosis, more surgical time in old and debilitated patients can be avoided. There are chances of post-laminectomy kyphosis which can be prevented by proper patient selection and OPLL progression which we think is only radiological without any clinical effect. This is a single surgeon, single hospital study and is the only study done on this pathology in Indian subcontinent with a long-term follow-up.

There are several limitations in this study. first, the study is retrospective and represents the experience of a single surgeon in a single institute.