Functional Evaluation of the Spinal
Accessory Nerve
After Neck Dissection
Bruce Leipzig, MD, Little Rock,
AR
James Y. Suen, MD, Little Rock, AR
Jim L. English, MD, Little Rock, AR
Jean Barnes, OTR, Little Rock, AR
Maria Hooper, OTR, Little Rock, AR
Modifications of the classic radical
neck dissection as described by Crile (1) have become increasingly
popular and, in many medical centers, are considered to be part of the
standard surgical armamentarium for the head and neck surgeon. The
impetus for many of these modifications has been the amelioration of
functional disabilities attendant upon classic radical neck dissection.
Prominent among these disabilities is the shoulder dysfunction that
results from sacrifice of the spinal accessory nerve. Excision of this
nerve results in anatomic and functional disabilities of the shoulder on
the operated side.
Bateman (2) has stated that the
trapezius muscle is an important part of the suspensory mechanism of the
shoulder. Trapezius paralysis allows the shoulder to droop, causes
abnormal rotation of the scapula in abduction, and causes considerable
aching and pain in the shoulder. When the trapezius is weak or
paralyzed, the scapula is unstable and flares out or wings, as is
commonly observed after radical neck dissection. Nahum et al (3)
attribute the shoulder syndrome resulting from radical neck dissection
entirely to trapezius palsy after accessory nerve destruction. They
attribute the pain to strain placed on other supporting shoulder
muscles, such as the rhomboids and levator scapulae, because of the
drooping of that shoulder.
Despite this knowledge, there has been
no prospective study to evaluate the disability associated with a
treatment program involving radical neck dissection and modifications of
it which, to varying degrees, spare the spinal accessory nerve. It is
assumed that these modifications of neck dissection cause less
disability than the traditional procedure. Nevertheless the point is
contentious and still unresolved. The purpose of this study is to
quantitate the degree of permanent disability associated with the
radical neck dissection and modifications of it.
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Materials and Methods
All patients who underwent neck dissections on the head and neck
oncology service at the University of Arkansas for Medical Sciences from
January 1980 to June 1982 were evaluated before surgery by an
occupational therapist. Objective measurements of range of motion and
muscle strength were taken at the neck, shoulder, and scapula
bilaterally. Additionally, the patients answered subjective questions
regarding their activities of daily living to correlate this information
with further measurements of shoulder function. Independently and
without the knowledge of the participating therapists the operating
surgeons (ourselves) assigned a risk factor to each patient after
performing what was considered to be the appropriate cancericidal neck
dissection (Table I). In the immediate postoperative period and again 6
months later, all measurements and questionnaires were repeated by the
occupational therapists.
One hundred nine patients were
evaluated for this study. The control group (risk factor 0,1) consisted
of 13 patients who all had major head and neck surgery, usually
wide-field laryngectomy, without further dissection into neck. The other
patients were evenly divided among those who underwent one of the two
types of modified neck dissections and those who had a classic radical
neck dissection. In one type of modified procedure, the submaxillary,
jugular, digastric, and upper and midjugular groups of nodes were
removed (risk factor 2) (Figure 1). For patients with cancer of the
hypopharynx or larynx, this modified procedure also included the lower
jugular group of nodes and the posterior cervical nodal groups (risk
factor 3). In none of these modified procedures was the spinal accessory
nerve, jugular vein, or sternocleidomastoid muscle removed. Exact
technical details of this procedure have been described elsewhere by
Suen (4). The second type of modified procedure was performed on
patients whom we believed required a radical neck dissection for
clinically positive nodes, but the spinal accessory nerve did not appear
to be in close proximity to the nodes. This procedure removes every
nodal group, as in a classic radical neck dissection, but spares the
spinal accessory nerve, which is dissected out throughout its course
(risk factor 4). Any patient whose neck was staged preoperatively or at
the time of surgery as N2 or N3 had a classic radical neck dissection
with sacrifice of the spinal accessory nerve.
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Results
The results of this analysis are presented in Tables II through IV. An
evaluation of 13 control patients validated the objective means of the
overall evaluation. In none of the 13 patients was there any change in
the range of motion or muscle strength at the neck, shoulder, or on the
lifting objects. One patient with shoulder drop was documented to have
had it since previous injury.
Among patients who had modified neck
dissection with preservation of the spinal accessory nerve, jugular
vein, and sternocleidomastiod muscle (risk factors 2 and 3), the
distribution of subjective disability (that is, pain) correlated
exceedingly well with decreased objective movement and strength at the
neck and shoulder (Table II). In almost every case among 36 patients so
treated, the degree of objective loss of range of motion and strength
was increased as the subjective experience of pain increased. In other
words, patients who complained of increasing pain on reaching above the
level of their shoulder had an average decrease in range of motion and
muscle strength of 23 percent at the neck and 26 percent at the shoulder
when those measurements were compared with others taken 6 months after
modified neck dissection (preoperative versus postoperative values).
Those with less pain, had an average decrease of only 11 percent at the
neck and 7 percent at the shoulder.
In all patients, when dysfunction of
the shoulder was evident there was winging of the scapula of 13 to 15
percent. This measurement was constant throughout all groups and
undoubtedly represented the degree of abduction and outward rotation of
the scapula when there is a loss of stabilization by the scapula when
there is a loss of innervation by the spinal accessory nerve only.
In the group of patients with the
modification of neck dissection in which the spinal accessory nerve was
spared but all nodal groups removed in an otherwise classic radical neck
dissection (risk factor 4), a different distribution of patients was
discovered (Table III). Eighteen of 28 patients so treated had minimal
dysfunction (65%); however, 5 of those 18 patients (29 percent) had
shoulder drop and scapular winging which indicated a loss of spinal
accessory nerve function. Overall, 14 of 28 patients (50%) had loss of
spinal accessory nerve innervation to the trapezius muscle, as
documented by objective measurement. This apparent discrepancy between
functional usefulness of the shoulder muscles (50%) was significant.
Among 35 patients treated with a
classic radical neck dissection (Table IV), 14 had subjective evidence
of minimal pain and dysfunction (40 percent). A much larger percentage
of these patients had pain on attempted use of that shoulder (that is,
rewaching or lifting) and nearly all had evidence of objective shoulder
dysfunction. Nevertheless, the fact that 40 percent of the patients had
minimal pain and dysfunction despite loss of innervation at the shoulder
seems important.
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Comments
The type of neck dissection to be chosen for therapy of metastatic
carcinoma from the head and neck remains a therapeutic dilemma. Lindberg
has outlined the propaility of metestases to the neck from various sites
in the upper aerodigestive tract, and these data from the basis of much
of the literature on the technique and indications for functional
modifications of the radical neck dissection. Skolnik et al
detected no metastases in the posterior triangle among 51 neck
dissections for carcinomas in various sites of the head and neck in
which there were no positive jugular nodes. He concluded that the
posterior triangle could be preserved in radical neck surgery in a
clinically negative neck, making preservation of the spinal accessory
nerve very simple. This concept has been challenged by Conley and
questioned by Schuller et al, who confirmed a low frequency of
metatastic nodes involving the posterior triangle but found a large
percentage of metastases (42%) in close proximity to the spinal
accessory nerve where it comes to lie near the internal jugular vein.
These and other investigations have led to the introduction of modified
neck dissections as described herein.
Our study indicates that there may be a
functional disability associated with any neck dissection in which the
spinal accessory is dissected out and placed in some degree of traction.
If the risk of functional disability is great enough in the modified
neck dissections then the question of wheather the modified neck
dissection is as effective as the radical neck dissection for
controlling neck disease becomes meaningless, and the classic radical
neck dissection advocated by Hayes Martin would be the only logical
approach to surgical treatment of cervical neck disease. If there is no
functional advantage, all other arguements for modified neck dissections
carry little weight. Our analysis, however, is not that clear. Although
there may be functional disability associated with any type of neck
dissection, those neck dissections in which the nerve is minimally
dissected (risk factors 2 and 3) are associated with the least amount of
dysfuntion. Seventy percent of those patients and 60 percent of patients
in whom the spinal accessory neve was spared but otherwise was a classic
radical neck dissection (risk factor 4) who had no associated pain or
subjective dysfunction nevertheless had shoulder dysfunction by
objective measurement. The message here seems to be that dissection of
the spinal accessory nerve may not predictably alter the objective
shoulder syndrome of a classic radical neck dissection.
We have given consideralbe thought to
why 30 percent of these patients with minimal dissection of the spinal
accessory nerve (risk factors 2 and 3) had shoulder dysfuntion and pain
to some degree. The most likely possibilty is that near the entrance of
the nerve into the sternocleidomastiod muscle, the nerve commonly
divides and the branch to the trapezius may continue medially to the
muscle which makes it vulnerable to injury during the dissection of the
nodes underneath the lower sternocleidomastoid muscle and in the
posterior cervical triangle. This injury could be from transection of
the nerve or from strong traction.
It is important to note that there was
a large group of patients (40%) who underwent classic radical neck
dissection (risk factor 7) with minimal disability. These patients did
well despite the loss of trapezius innervation and despite the presence
of shoulder drop and objective loss of motion and strength at the neck
and shoulder. They have given impetus to retention of the classic
radical neck dissection as the standard from a functional point of view
by which all modifications must be measured and evaluated. Why some of
these patients did well and others did not is unclear, although it is
probably related to preoperative strength, activity, and motivation of
the patient. Those patients who are well developed, utilized their neck
and shoulder in daily work and other activities, and are therefore able
to use other compensatory muscles and movements may do better regardless
of the type of neck dissection performed.
There were several other factors not
considered in our evaluation that may have influenced the results. One
is that the majority of these patients were given instructions for
shoulder exercises and therapy by the occupational therapist
preoperatively and postoperatively. Also, shoulder braces were given to
most patients with a shoulder drop after surgery. We did not assess
whether patients followed the therapy program and to what extent the
therapy influenced the pain and dysfunction. The other factor not
evaluated was whether or not the patients received radiotherapy as
partof their overall treatment and whether our results may have been
influenced by the irradiation. Schuller et al (11) indicated that
the total treatment appeared to influence the degree of shoulder
dysfunction.
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Summary
The pain and dysfunction associated with a loss of innervation by the
spinal accessory nerve has motivated surgeons to modify the classic
radical neck dissection. A prospective study of 109 patients who
underwent either a radical neck dissection or a modification of it with
preservation of the spinal accessory nerve revealed that those patients
in whom the nerve, muscle, and vein were preserved had less dysfunction
(30%) than those with nerve preservation only (50%) or classic radical
neck dissection (60%). In addition, even when the functional disability
was the same, there was less associated pain with nerve-sparing
procedures. Furthermore, a large group of patients (40%) who underwent
classic radical neck dissection had minimal disability. Given these
results, a propsective study of recurrence data in these patients is
indicated.
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