Background
Among patients who develop permanent debilitating symptoms after whiplash trauma (referred
to as chronic whiplash syndrome henceforth), headaches and/or pain and stiffness in
the neck and shoulder are the most frequent complaints and reasons for disability
[[1 ],[2 ],[3 ]]. In addition, complex patterns of diffuse symptoms, including numbness, paresthesias,
vertigo, muscle weakness, or cognitive dysfunction, are common and have been shown
to correlate with post traumatic sleep deprivation [[4 ]] or brain stem dysfunction [[5 ],[6 ],[7 ]]. Yet, many patients claim disability in spite of normal findings on standard laboratory
tests. This has led to controversy in the literature as some authors argue that symptoms
are credible only if corroborated by laboratory findings [[8 ]] while others claim that negative studies do not exclude injury or the validity
of a complaint [[9 ],[10 ]].
Chronic symptoms from whiplash trauma have commonly been linked to pathology of the
spine and its supporting tissues, i.e. facet joints [[11 ]], spinal ligaments [[12 ]], and intervertebral discs [[13 ],[14 ]]. However, previous investigations have also demonstrated significant symptomatic
improvement, including temporarily decreased pain, increased cervical range of motion,
and higher peripheral pressure pain thresholds in chronic whiplash patients following
injections of local anesthetic into carefully selected areas of focal tenderness in
painful muscles [[15 ]]. The careful selection of ("key") tender points for injection appears to be critical,
as previously described efforts directed at non-specific trigger points have been
less effective [[16 ]].
Based upon these observations, a therapeutic approach to chronic whiplash has been
developed in which offending tender points that have been identified by a positive
response to infiltration with anesthetic are surgically exposed and then excised [[17 ]]. Typically, any removed tissue consisted of trapezius fascia, and thus the procedure
is reasonably described as a modified fasciectomy. A central feature of the surgical
strategy is that following incision and elevation of skin flaps, the patient is awakened
for key portions of the procedure to provide real time feedback to assist in identifying
and excising of pain generating tissue.
In a similar vein, Hagert et al. have reported that they treated chronic compartment
syndrome of the trapezius and entrapment of the spinal accessory nerve (SAN) in patients
with a history of overuse syndrome [[18 ]] and a clinical presentation that closely matches the pattern of symptoms observed
among patients with chronic whiplash. We therefore posited peripheral nerve entrapment
as a possible subcomponent of the chronic whiplash syndrome, and, in a selected group
of patients undergoing the procedure described above for chronic whiplash, included
neurolysis of SAN. The present manuscript describes the procedures, findings, and
long-term outcome in a series of patients undergoing spinal accessory nerve decompression
in combination with excision of tender points for chronic pain following whiplash.
Methods
The study group consisted of 30 consecutive patients treated by one surgeon (NAN).
The indication for surgery was established based upon the following:
• unremitting posttraumatic neck pain with a steady state for no less than six months,
most typically as a result of a motor vehicle crash-related injury;
• lack of lasting response to conservative or minimally-invasive therapeutic procedures,
including physical therapy, chiropractic treatment, zygapophyseal blocks, inter alia ;
• lack of a clearly delineated pain generator pertaining to the spine, such as a disk
herniation, fracture, or foraminal or central spinal stenosis;
• prompt response to anesthetic infiltration of key tender points in the region of
the upper trapezius muscle (at least 50% reduction of the most intrusive symptoms).
Anatomical considerations
During its extracranial course, the SAN forms a plexus with fibers from spinal nerves
C3 and C4 [[19 ]] before traversing the posterior triangle. In order to minimize the risk of surgical
complications during exploration of the ventral aspect of the trapezius, the nerve
must be exposed and protected ([Figure 1 ]).
Figure 1 Trajectory of the spinal accessory nerve in the posterior triangle (cadaveric
dissection) .
Surgical technique
Patients are placed in a lateral or beach-chair position on the operating table. Under
local anesthesia (1-3 cc of Lidocaine® 0.5%) and short-acting IV sedation (Propofol® ), the posterior aspect of the trapezius muscle is exposed through a sagittally oriented
skin incision across the shoulder. While the patient is still anesthetized generally
thickened fascia, including septae between bundles of the muscle, are excised from
the painful area of the muscle according to preoperative skin markings corresponding
to the previously identified key tender points. The dissection is continued anteriorly
along the leading edge of the trapezius until the SAN was identified. In most of the
cases adhesions were identified between the nerve and the underlying fascia.
The patient was then awakened in order to provide feedback during the exploration
of areas of greatest focal pain. The skin had been marked pre-operatively to indicate
where the key areas of focal tenderness had been identified previously based upon
response to local anesthetic. While awake, patients were asked to identify “old” (preoperative)
pain and differentiate it from “new” (surgical) pain.
Patients generally signaled incremental improvement during resection of fascia and/or
interfascicular septae within the trapezius. Although the SAN neurolysis in some cases
was observed to have a direct effect on the patient’s headache complaints, the fasciectomy
tended to have a greater immediate effect on mobility.
Data collection
A linear visual analogue scale graded from 0 (not disabling) to 10 (completely disabling)
was used to define a ’disability score’ for each of five different indices: pain,
headache, insomnia, muscle weakness, and neck/shoulder stiffness. Assessments were
made for the week preceding surgery, and at follow-up 12-18 months post op.
Hospital charts were reviewed for information pertaining to surgical technique and
findings. Outcome data was compiled from questionnaires completed by the patients
12-18 months after the operation.
Statistical analysis
Student’s t -test for paired samples was used for the analysis of outcome data. Statistical significance
was defined as p ≤ 0.05.
Results
Patients
The study group consisted of 6 males and 24 females presenting to UNMC for treatment
for chronic symptoms after whiplash. The average age at the time of surgery was 43
years (range 27-66). The mean and median time from the onset of symptoms until surgery
was 41 months (range 7-156) and 24 months, respectively. All of the patients stated
that their condition had reached a steady state at the time of the operation.
Fourteen patients reported that their condition had been precipitated by a classic
rear-impact motor vehicle crash. The remaining 16 patients reported various other
mechanisms of trauma, including falls and sports injuries.
Preoperative complaints and clinical findings
Only “pain” was identified by all 30 patients as an independent preoperative reason
for disability. Each of the remaining four variables (headaches, sleep deprivation,
stiffness, and weakness) was a reason for disability in 26 or more patients prior
to surgery ([Table 1 ]).
Table 1
Reported incidence of five separate symptoms, described as disabling by 30 patients
prior to surgery.
Reason for disability
Number of patients
Pain
30
Headache
27
Sleep deprivation
29
Weakness
26
Stiffness
27
Four clinical signs were documented in all cases prior to surgery: (1) asymmetric
posture, typically with the shoulder elevated on the side of greatest pain; (2) decreased
and painful range of motion in neck and shoulder(s); (3) tenderness to palpation along
the horizontal portion of the upper trapezius muscle; and (4) greater than 50% of
reduction of pain and increased mobility following infiltration of 2-3 cc of local
anesthetic into 1-3 key areas of focal tenderness in the upper trapezius.
Neck/shoulder stiffness, which was observed but not objectively measured in most patients
before surgery ([Additional file 1 ]), was understood primarily as an expression of pain inhibition.
Surgical interventions
Key portions of each operation were performed without anesthesia, in order to allow
communication between the patient and the surgical team. Thus, the extent of neurolysis
and fasciectomy was routinely defined by patients’ direct feedback including functional
testing, e.g. of mobility ([Additional file 2 ]). The procedures were well tolerated by all participants tolerated the procedures
well. Recovery was generally rapid, with most patients mobile and ambulatory within
the first postoperative days ([Additional file 3 ]). There were no major surgical or postoperative complications.
Histological findings
No pathologic findings were noted in any specimens that, in a majority of patients,
were submitted for routine microscopy.
Long-term results
Eighteen patients (60%) reported improvement in all 5 of the assessed indices (neck
pain, headaches, insomnia, weakness and stiffness) and an additional 10 patients (33%)
reported improvement in at least one parameter, for a total of 93% of patients reporting
a lasting positive outcome one year or more following the surgery. One patient did
not report any benefit from the operation, noting that her condition was unchanged.
Another patient reported increased stiffness after the operation, but at the same
time noted that three other symptom areas had improved ([Table 2 ]).
Table 2
Changes in symptom-derived disability scores at follow up one-year after surgery.
Percent change
0%
1 < 30%
30% < 50%
50% <100%
100%
n
Pain
2
0
9
13
6
30
Headache
2
1
2
12
10
27
Insomnia
10
2
3
10
4
29
Weakness
4
2
5
11
4
26
Stiffness
1
1
6
12
8
28
Calculations based on patients’ assessments (VAS; 0% = no improvement, 100% = complete
improvement). Whereas 27 patients reported stiffness as a reason for disability before
surgery, the number increased to 28 after the operation. One patient who experienced
more stiffness after surgery is represented as “0% improvement”.
Mean VAS-scores were significantly lower than before surgery for all five variables
(Table 3). Specifically, the score for over-all pain decreased from 9.5 ± 0.9 to 3.2
± 2.6 ([Figure 2 ]).
Table 3
Symptom-derived disability scores before surgery, and one year after surgery.
Symptom
Before
After
p
Pain
9.5 ± 0.9
3.2 ± 2.6
< 0.001
Headache
8.2 ± 2.9
2.3 ± 2.8
< 0.001
Insomnia
7.5 ± 2.4
3.8 ± 2.8
< 0.001
Weakness
7.6 ± 2.6
3.6 ± 2.8
< 0.001
Stiffness
7.0 ± 3.2
2.6 ± 2.7
< 0.001
Numerical values represent patients’ self-assessments, using a linear Visual Analogue
Scale (VAS) graded 0-10 for 0 = “Nothing at all” and 10 = “Completely disabling”.
Figure 2 VAS-scores for global pain before (1) and one year after (2) surgery . n = 30.
Prior to the operation, 27 patients complained of head pain/headache. After surgery
22 patients stated that their head pain had been reduced by at least 50%, and 10 of
these patients stated their headaches had been completely eliminated ([Figure 3 ]). Of the 17 patients who continued to experience headaches, all reported that the
episodes were less frequent than before surgery, a reduction from 5 ± 2 days/week
to 1.4 ± 2 days/week.
Figure 3 Impairment caused by headache (VAS) at one-year follow-up relative to pre-surgical
symptoms . 1 = No change; 2 = < 30% reduction; 3 = 30-49% reduction; 4 = 50-99% reduction;
5 = complete resolution. n = 27.
Fourteen patients of 29 stated that the severity of their sleep deprivation (insomnia)
had decreased by 50% or more as a result of the operation. The average number of hours
of sleep per night increased from 4 ± 1 to 6 ± 2 for the entire cohort. Similarly,
postoperative perception of disability decreased by at least 50% in 15 of the 26 patients
reporting weakness, and in 20 of the 28 patients reporting stiffness, in comparison
with pre-operative perceptions.
Discussion
We describe the long-term outcome after surgical fasciectomy and SAN neurolysis for
symptoms associated with chronic whiplash pain. In this series of 30 patients, 29
described a lasting overall improvement that they attributed to the treatment, although
in one case with satisfactory pain reduction, the procedure resulted in increased
neck stiffness. One patient who did not benefit from the surgery reported no degradation
or other worsening of symptoms or disability during the year following the operation.
Our results suggest that some of the most common symptoms found in chronic whiplash
(e.g. headaches, stiffness of the neck, and pain in the shoulder/neck region) may
be secondary to either primary injury in, or secondary dysfunction of the spinal accessory
nerve and/or the trapezius muscle. We conclude, with caution, that the condition represents
an indication for surgical treatment in selected cases where more conservative measures
have proven ineffectual.
What is less clear is how or why the trapezius muscle and SAN are involved in perpetuating
the chronic whiplash syndrome. The traditional portrayal of SAN as one of pure motor
function has been challenged by anatomical studies [[20 ],[21 ]], and our experience with surgical manipulation of the nerve in alert and unanesthetized
patients has confirmed that it indeed is one of mixed sensory and motor function.
This finding raises the possibility of SAN injury or entrapment as a cause of neurogenic
pain, in addition to and independent of gross loss of motor function [[22 ],[23 ],[24 ]]. Previous reports that surgical neurolysis alone can provide immediate relief of
symptoms related to a lesion of SAN further suggest entrapment by scar tissue, rather
than nerve damage per se , as a reason for some preoperative symptoms [[19 ],[25 ]].
Based upon the present data we cannot discern to what extent preoperative symptoms
were expressions of dysfunction in the SAN versus the trapezius muscle and/or fascia.
It has been reported, however, that patients with chronic whiplash syndrome exhibit
higher EMG activity in the upper trapezius muscles than healthy control subjects,
as well as a reduced ability to relax the muscle to baseline levels after a dynamic
task [[26 ]]. Larsson et al. found that chronic neck pain may be associated with disturbed microcirculation
in the trapezius [[27 ]], and Hagert et al. presented clinical data suggesting chronic trapezius ischemia
in a chronic pain syndrome nearly identical to that of our patients [[18 ]]. Thus, we cannot exclude that the most beneficial part of the surgery described
herein was decompression of a chronic compartment syndrome in parts of the segmented
trapezius muscle.
Limitations
The conclusions that can be drawn from this investigation are limited by the size
of the study group, the retrospective, non-randomized study design, and the subjective
assessment instrument. It is not possible to draw a firm conclusion as to the relative
importance of fasciectomy versus neurolysis, since dissection of the SAN was necessary
in all patients to protect the nerve during resection of fascia from the ventral aspect
of the trapezius.
Conclusions
The results described herein offer a potentially new direction in evaluation and surgical
treatment of chronic whiplash syndrome. Entrapment of the spinal accessory nerve and/or
chronic compartment syndrome of the trapezius muscle may cause chronic debilitating
pain after whiplash trauma, without radiological or electrodiagnostic evidence of
injury. In such cases, surgical treatment may provide lasting relief. Continued research
using randomized and controlled study designs will further advance the understanding
and extrapolability of the present findings.
Additional material
Pre-operative shoulder function . Video documentation of shoulder range of motion before surgery. Limited range of
motion in right shoulder prior to surgery, in a patient with 10-year history of chronic
whiplash from a motor vehicle crash.
Patient feed-back during surgery . Video documentation of surgical procedure. Functional progress during neurolysis
of spinal accessory nerve and trapezius fasciectomy. The unanesthetized patient cooperates
actively and provides guidance to the surgical team.
Post-operative shoulder function . Post-operative status. Video documentation of range of motion in right shoulder
one day after trapezius fasciectomy and neurolysis of spinal accessory nerve.
Abbreviations
SAN::
Spinal accessory nerve
Competing interests
The authors declare no competing interests. No external funding was received for this
research.
Authors’ contributions
All coauthors participated in two or more key elements (study design, data collection,
analysis of data, manuscript preparation) of this investigation, and read/approved
the final manuscript.