Different signs and their interpretation
The following factors are examined and compared with the opposite side. Note if any abnormality is present.
• Bulk and nutrition of the muscle
• Tone of the muscle
• Power of the muscle
• Deep reflexes
• Superficial reflexes
• Coordination of movements
Bulk and nutrition of the muscle
Expose both the upper and lower limbs and compare the corresponding parts of both sides with each other. Look if any side has more bulk than the other. One side may have less bulk(atrophy) or increased mass(hypertrophy).
The atrophy of a single side can be detected easily as the wasted muscle is small and soft. If there is any doubt, follow this procedure:
Take a point from an equal distance to a bony prominence and measure the circumference of the muscle on both sides and compare it. For example, for forearms, take a point on the forearm where the muscle bulk is maximum, and measure its distance from the styloid process of the radius. Measure the circumference of the muscles at that point. Now measure the circumference of the muscle of the opposite side at the same distance from the styloid process of the radius as measured earlier.
If it is similar on both sides, muscle bulk and nutrition are normal. If there is atrophy of a muscle, the circumference will be small.
In which conditions does Atrophy occur?
When a muscle is not used, its wasting starts. This is known as disuse atrophy. For example, in joint disease, the patient refers not move the limbs to prevent pain. Due to the disuse of the muscle, its atrophy
starts. Atrophy is also seen in the lower motor neuron type of lesion.
Bilateral atrophy is somewhat difficult to pick until it is significant.
Hypertrophy is the increase in muscle bulk or size. It may be;
• True hypertrophy
• Pseudo hypertrophy
In this type of hypertrophy, both the power and bulk of the muscle increase. It may be due to excessive muscle use, for example, in athletes and bodybuilders.
In this type of hypertrophy, the bulk of the muscle is increased while its power is decreased, for example, in Duchenne muscular dystrophy.
Check the tone of the muscle
The tone is the resistance felt when the movement is carried out passively at a joint.
Muscle tone may increase(hypertonia) or decrease(hypotonia) in different diseases.
How to check the tone of the muscle?
The patient must lie comfortably and supine. Carry out passive, full-range movements at the joints and feel the resistance.
Causes of hypertonia
Tone of the muscle is increased in :
• Upper motor neuron to of lesion
• Lesion of the basal ganglion
• Parkinson’s disease
The tone is decreased in :
• Lower motor neuron type of lesion
• Cerebellar dysfunction
Power of the muscle
The power of the muscle is compared on both sides to detect if any weakness is present.
There are five grades of power
Grade 0: No movement
Grade 1: only flickering contractions
Grade 2: can not move against gravity, only horizontal movements
Grade 3: Can move against gravity but not against resistance
Grade 4: can move against resistance, but the power is suboptimal
Grade 5: normal power, can move against resistance
Reflexes are elicited only if the whole of the reflex arc is intact. The reflex arc consists of two limbs, afferent and efferent. The nerves involved in the reflex arc are the root values of the reflex.
These are the deep reflexes, also called tendon jerks:
• Ankle jerk
• Knee jerk
• Biceps jerk
• Triceps jerk
• Brachioradialis jerk
Protocols while eliciting a reflex
• Ask the patient to sit comfortably.
• Expose the muscle to be tested.
• The hammer should be in free fall state.
• Strike the tendon, not the muscle.
• Compare each jerk on both sides.
Knee jerk (root value L3, L4)
Follow the above protocols. Flex the knee. Feel the quadriceps tendon between the patella and tibial tuberosity. Support the knee with your left hand. Strike the quadriceps tendon with the clinical hammer. Feel the contraction of the quadriceps.
Ankle jerk(root value S1, S2)
The patient should lie supine. Flex the leg. Dorsiflex the foot by placing your left hand on the sole. Strike the Achilles tendon with the hammer. Note the contraction of the calf muscles.
Biceps jerk(root value C5, C6)
Feel the tendon and f biceps brachii muscle. Place your thumb over the tendon while the arm is flexed and semipronated. Strike Your thumb with the clinical hammer. Root value is intact if the reflex is elicited.
Triceps jerk root value(C6, C7)
Flex the arm of the patient at the right angle. Strike the tendon of the triceps muscle above the olecranon process.
Brachioradialis jerk (root value C5, C6)
The tendon of the brachioradialis muscle is present proximal to the styloid process of the radius. Feel the tendon and strike it while the forearm is flexed and semipronated. See the contraction of brachioradialis.
Superficial reflexes include
• Plantar reflex
• Abdominal reflex
• Cremasteric reflex
• Conjunctival and corneal reflex
If patient should lie supine. Grasp the ankle and scratch the outer edge of the sole of the feet with some blunt object like a key starting from the heel towards the little toe and them medially. There will be plantarflexion of the great toe and adduction of other toes. This is the normal response and is called a negative babinski’s sign.
If there is dorsiflexion of the great toe accompanied by fanning of other toes, it is called a positive babinski’s sign. It may be due to the upper motor neuron type of the lesion or deep coma.
The patient should be lying supine. Draw a diamond around the umbilicus with a pin. Avoid damage to the patient. There will be a brisk contraction of the abdomen muscles, and the umbilicus will move towards that side. This is a normal response.
It is elicited in man. Scratching the medial side of the thigh causes elevation of the testes. It is absent in upper motor neuron lesions (UMNL).
Conjunctival and corneal reflex
Ask the patient to look medially. Touch the cornea or conjunctiva with a wisp of cotton. There will be sudden closure of the eyes.
Coordination of movements
It means smooth and purposeful movements. It not only requires an intact motor system but also requires intact sensory and cerebellar system.
Deep reflexes are exaggerated in upper motor neuron lesions and diminished in lower motor neuron lesions.
If all these are intact, one can say that the motor system is intact.