The role of iatrogenic foraminal stenosis from lordotic correction in the development of C5 palsy after posterior laminectomy and fusion

Abstract

BackgroundPost-operative C5 nerve root palsy is a known complication following cervical spine surgery. Although several theories have been proposed, there remains no consensus as to the etiology of the palsies. Multiple pre-operative radiographic measures have been assessed for utility in predicting palsy. The purpose of this study is to evaluate published radiographic parameters as well as specifically evaluate the effect of cervical lordosis in the development of C5 palsy to establish thresholds that reliably predict the incidence.MethodsThis study is a retrospective review of 54 consecutive multilevel cervical laminectomy and fusion surgeries performed by a single spine surgeon between June 2007 and February 2014. Pre-operative MRI and pre- and post-operative plain films were assessed to measure anteroposterior diameter (APD) of the spinal cord, cervical laminar angles, anteroposterior foraminal diameters (FD), cervical curvature index (Ishihara), cervical spine angle (C2-7), and C4-5 angle. Univariate analysis through independent t tests was used to compare differences between groups. Stepwise logistic regression was performed to identify pre-operative variables associated with C5 palsy. Receiver operating characteristic curves were created for significant variables to assess predictive accuracy through determining the area under the curve.ResultsThere were 13 (24 %) palsies in the 54 patients in the study. All palsies completely resolved within 6 months. Among pre-operative measures, FD and APD were significantly different between the palsy and non-palsy groups. The average post-operative C4-5 angle was significantly different between the groups, though the cervical spine angle and curvature index, as well as the change in these measures from pre-operative measurements, did not differ significantly between groups.ConclusionsPost-operative palsy is likely a result of iatrogenic nerve root compression from a decreased in cross-sectional area of the neuroforamen in a patient with pre-operative narrowing of the foramen. However, spinal cord drift back may also play a role from the combined effect of posterior decompression from laminectomy and relative slack afforded by increased lordosis. Accordingly, increased post-operative lordosis would increase the likelihood of effect from both of these mechanisms. We recommended limited conservative lordotic correction in patients with pre-operative foraminal narrowing.

Characteristics of deformity surgery in patients with severe and rigid cervical kyphosis (CK): results of the CSRS-Europe multi-centre study project

“…In three reviews focused on AS patients, the sample sizes were 188-286, 19-23% of patients had neurologic complications mostly in the form of a transient C8-radiculopathy, and 3-4% had permanent spinal cord deficits. Kurakawa [70], Nakashima [71], Hojo [72] and Blizzard [73] reported an increased rate of C5-palsy with increasing CK-correction without preventive foraminotomy. In a series of 16 patients that underwent circumferential release and 3CO, 19% had postop temporary C5-palsy [34].…”

Impact of the surgical strategy on the incidence of C5 nerve root palsy in decompressive cervical surgery

“…They display an overall postoperative palsy rate of 10.9%. Although a rate up to 24% can be observed, most studies reported similar numbers[ 7 , 22 ]. However, most of these studies are not comparable to each other.…”

“…In order to minimize the risk of C5 nerve root stress due to spinal cord shift, additional decompression of the neuroforamen can be considered. Several studies demonstrate that preoperative anteroposterior diameter of the neuroforamen was found to be significantly smaller in patients with C5 palsy[ 7 , 11 , 25 ]. As a consequence, when a wide decompression, which includes more than one level or a corpectomy with potential excessive shifting of the spinal cord is required, prophylactic foraminotomy at the level C4/5 might reduce C5 nerve root palsy, as we performed in all of our procedures in which the segment C4/5 was involved.…”

“…Although postoperative C5 nerve root palsy generally has a good prognosis with a spontaneous full recovery in most of the cases within the first six months after surgery, it has a severe impact on the patients’ rehabilitation and quality of life. Patients with more severe and bilateral palsy or loss of somatic sensation with pain, however, require significantly longer recovery times of up to two years[ 2 , 3 , 5 – 7 ].…”

Cervical curvature changes following laminectomy with lateral mass screw fixation: Does it relate with spinal cord shift and clinical efficacy

“…believed that the increase of postoperative cervical lordosis was negatively correlated with the severity of axial pain, especially for lordosis greater than 20°. While the increased cervical lordosis would promote the backward drift of the spinal cord, and further increase the tension of C5 nerves, leading to the occurrence of C5 palsy [20]. For this contradiction, since the balance point of cervical curvature is di cult to select, it is di cult for spine surgeons to balance the occurrence of AS and C5 palsy by controlling the cervical curvature.…”