Sir,
A 53-year-old male had undergone C4–C5 discectomy, interbody grafting and C4–C5 fixation
with anterior cervical plate and screws 4 years ago for a posttraumatic C4–C5 dislocation
[[Figure 1]] following fall from a running train. At the time of presentation, he had neck pain,
and only motor deficits were the weakness of right biceps and deltoid muscles. Postoperatively,
he had a complete recovery.
Figure 1: Images after the initial injury (a) X-ray cervical spine (lateral) showing a C4 on
C5 subluxation; (b) T2 sagittal image showing dislocation with no cord signal change
and (c) postoperative X-ray showing reduction with C4-C5 fixation with anterior cervical
plate and screws with an interbody graft
Most patients would be careful after recovery from spinal injury. However, our patient
was clearly a case of “once bitten, still not shy” and 4 years later (at the age of
57 years) he presented with a history of fall while trying to climb a moving bus and
lost power in both lower limbs, bilateral wrists, and fingers and had decreased sensation
below D4 dermatome. He also developed retention of urine and had to be catheterized.
His plantars were bilaterally extensor. A magnetic resonance imaging of the cervical
spine showed C5–C6 disc prolapse and extrusion with superior migration and tear of
the posterior longitudinal ligament, causing cord compression with signal changes
from C5 to C7 levels [[Figure 2]]. He underwent C5–C6 anterior cervical discectomy and grafting. It was planned to
remove the previously inserted plates and revise with a longer construct. However,
as the previously inserted plate could not be removed, we proceeded to do a posterior
C5–C6 lateral mass fixation with C4–C6 laminectomy and decompression of thecal sac.
He had slow neurological improvement and 1 year postoperatively he was off catheter,
independently ambulant with a spastic gait and had regained some ability grip objects.
Figure 2: Images after the second injury (a) X-ray cervical spine (lateral) showing solid bony
fusion between C4 and C5 with previous intact construct; (b) T2 sagittal and (c) images
showing construct (green arrows), posterior longitudinal ligament injury and extensive
cord signal changes with torn posterior longitudinal ligament and extruded disc fragment
at C5-C6 level; (d) postoperative X-ray showing C4-C6 laminectomy with C5-C6 lateral
mass screws in situ in addition to previously placed plates and screws
While cervical spine injuries are common in previously occurring in previously fused
spines – whether congenital or following ankylosing spondylitis and have been described
following surgery for nontraumatic conditions,[[1]],[[2]] a second traumatic cervical spinal injury is very rarely described in literature.[[3]],[[4]] In these reports,[[3]],[[5]] injuries occurred in patients who had previously been subjected to instrumented
spinal fusion – for a C7-D1 dislocation in one case[[5]] and for a D2 compression fracture in another.[[3]] Both authors state that one of the causes of the second injury in their patients
was the lack of mobility in the fused segments which caused excessive stress at the
instant of trauma in adjacent mobile levels causing in one case a C5 burst fracture[[5]] and in another a C5–C6 dislocation.[[3]] Our patient too had undergone instrumented fusion at C4–C5 level, and the second
injury occurred at the immediate lower level.
Adjacent segment degeneration (ASegD) after cervical fusion is a well-known entity[[2]],[[4]] and radiological ASegD in found in up to 47% of patients undergoing anterior cervical
discectomy and fusion. Although speculative, it is probable our patient had developed
an element of disc degeneration at C5–C6 level that led to its extrusion and cord
compression following injury. Finally, despite having sustained a previous injury,
our patient did not cease his unsafe travel practices. Alcohol consumption[[3]] and thrill-seeking behaviour[[3]] have previously been identified as predisposing factors for a second traumatic
injury, and surgeons must be aware of these multiple factors and counsel at-risk patients
accordingly.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
