Recovery of elbow flexion is considered as top priority in reconstruction following
brachial plexus injury, hence lot of procedures have been described to restore it
[[1],[2],[3],[4]]. Nerve transfer is the most preferred method unless the patient presents very late.
To assess the recovery of elbow flexion Medical Research Council Grading has been
most commonly used worldwide. Serious limitations of MRC grading system have been
expressed by many authors [[5],[6]] but it continues to be in use because of its simplicity. Many modifications have
been used by various authors [[5],[6],[7],[8],[9]] but none are widely used. We believe that for any grading system to be widely acceptable
it need to be a modification of the existing MRC grading system as this has been fed
into at least three generations of residents and all are very used to and comfortable
using this scale, may be at cost of accuracy. In addition, the grading system has
to be comprehensive, easy to use and reproducible.
We have been using a modified MRC grading scale to assess the recovery of elbow flexion
following nerve transfer in our patients ([Table 1]). This is a very simple grading system which basically is an elaborated MRC scale.
The grade 0 and 1 remains same. Division of Grade 2 & 3 is influenced by the active
motion scale described by Curtis et al [[9]]. Grade 2 has been subdivided into three subdivisions; A, B & C based on the range
of motion with gravity eliminated. Grade 3 has been similarly subdivided depending
on the range of motion against gravity. The subdivision of Grade 4 is based on the
patient’s ability to lift the weight through full range of flexion on a biceps curl
machine, with weights in 0.5 Kg increments, a commonly used machine in physiotherapy
departments and gymnasiums to strengthen the biceps. Grade 4 has three subdivisions;
A- if the patient is able to lift less than 30% weight of the normal side; B- if he
is able to lift 30–60% weight of the normal side; and C- if he is able to lift more
than 60% weight of the normal side. Grade 5 will mean normal strength i.e. able to
lift the same amount of weight as the normal side.
Table 1
Modified Medical Research Council system of grading elbow flexion
|
Grade
|
Subdivision
|
Description
|
|
0
|
-
|
No contraction
|
|
1
|
-
|
Perceptible contraction in the muscle but no movement
|
|
2
|
|
Gravity Eliminated
|
|
A
|
Motion less than or equal to half range
|
|
B
|
Motion more than half range
|
|
C
|
Full range of motion
|
|
3
|
|
Against Gravity
|
|
A
|
Motion less than or equal to half range
|
|
B
|
Motion more than half range
|
|
C
|
Full range of motion
|
|
4
|
|
Motion Against Resistance
|
|
A
|
Able to lift less than 30% weight of the normal side through full range
|
|
B
|
Able to lift 30–60% weight of the normal side through full range
|
|
C
|
Able to lift more than 60% weight of the normal side through full range
|
|
5
|
|
Normal strength
|
We have found this scale very easy to use and reproducible. It has several advantages;
by subdividing grade 2 and 3 we are able to track the recovery better, this not only
helps the treating team to assess the recovery but also gives lot of confidence to
the patient by knowing that he is improving. This is an important part for any nerve
injury management as the nerve recovery takes very long time, may be months before
patient migrated from grade 2 to grade 3, in which period patient may be very anxious
and doubtful. By further subdividing these two grades we can actually show the progressive
recovery to the patient and boost his confidence. Also, it will allow comparing the
rate of recovery following different nerve transfer techniques.
Grade 4 is the least defined of all the grades in MRC system because of its widespread
range [[5],[6]]. If a patient is able to lift 1 kg weight he is labeled as grade 4 and another
patient who is able to lift 20 kg is also grade 4. The difference between these two
is phenomenal, both from functional point of view and for assessment of the final
outcome following a surgical procedure. The data of the experimental study conducted
by MacAvoy and Green [[5]] showed that grade 4 alone represents 96% of the entire spectrum of potential strength
of the particular muscle and hence demands subdivisions for more precise assessment
and documentation. They suggested that gross subjective estimate of strength as percentage
of the normal side would be more useful than the MRC scale. But we believe that it
will be too subjective and preclude standard and reproducible assessment.
Subdividing the grade 4 into three subgroups based on the percentage of weight a person
could lift on a biceps curl machine is definitely useful. It allows us to objectively
assess and document the recovery and the final functional outcome. With most of the
nerve transfer procedures described now claiming grade 4 recoveries in more than 80%
of the reported cases [[2],[3],[4],[10],[11],[12],[13]] it is high time we get more detailed assessment of this grade lest we shall be
comparing ’apples with oranges’. Definitely all grade 4 labeled can not equate to
good functional results. This subdivision shall give us clearer picture of the functional
recovery and dictate the supremacy of one procedure over the other. A grading system
similar to this may be applied to other muscle assessment as well.
Abbreviations
MRC Grade:
Medical Research Council Grade
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
PB: Conceived the idea, collected the relevant literature, designed the modified classification
and wrote the article.
NB: Designed the modified classification and used it in the clinical practice.
Both the authors have read the final version of the article and agreed to its content.
