MOTOR EXAM: ABNORMAL EXAMPLES
Upper extremities – Inspection & Palpation
In this patient there are fasciculations (spontaneous contraction of a motor unit) noted in the deltoid muscle as well as atrophy. There is also atrophy of the interosseous muscles of the hands. These findings can be seen in motor neuron disease such as amyotrophic lateral sclerosis.
Tone - Upper extremity
There is increased tone in the right upper extremity that is rate dependent with the clasp-knife phenomena noted when the arm is flexed. This is spasticity from an upper motor neuron lesion.
Strength testing - Upper extremity
With an UMN lesion the fine, fractionated movements of the fingers and hand are lost. Distal extremity weakness is greater than proximal weakness. With greater effort to move the paretic hand, there is overflow activation of proximal muscles and even of the contralateral hand, which produces mirror or synkinetic movements.
Stretch or Deep Tendon Reflexes - Upper extremity
It is always important to compare right vs. left. The first patient shown has hyperreflexia or 3+ DTR's of the right biceps, triceps and brachioradialis. The second patient has hyperreflexia of the right finger flexors. Hyperreflexia is one of the signs of a UMN lesion.
Testing for pronator drift - Upper extremity
With an UMN lesion there is pronation and downward drift of the outstretched supinated arm. This is because the pronators overpower the weaker supinators. Another name for this sign is a pronator Babinski.
Lower extremities – Inspection & Palpation
There is hypertrophy of this patient's left leg. Closer inspection of that extremity shows hyperpigmented skin lesions suggesting segmental neurofibromatosis. A thorough skin search can provide important clues to diagnosis especially in the neurocutaneous syndromes.
Tone - Lower extremity
There is spasticity on passive range of motion of the patient's right ankle with decrease range of motion and clonus which is caused by repetitive contraction of the stretched gastrocnemius muscle. Range of motion at the knee would also demonstrate spasticity. These findings are part of the UMN syndrome.
Strength testing - Lower extremity
Testing of the muscle strength in this patient shows 1/5 weakness of dorsiflexion, plantar flexion, inversion and eversion of the right ankle with normal proximal strength.
Stretch or Deep Tendon Reflexes - Lower extremity
There is hyperreflexia of the right knee jerk (3+) with a rightsided crossed adductor response (the crossed adductor contraction occurred because of the increased right leg tone which resulted in reflex contraction of the adductor magnus with the very slight stretch of this muscle caused by tapping the opposite knee). There is also hyperreflexia with clonus (4+ DTR) of the right ankle. The second patient demonstrates a 4+ ankle jerk on the left with sustained clonus.
Hyperreflexia is one of the signs of the UMN syndrome.
Plantar Reflex - Lower extremity
The patient has a Babinski sign on the right with an up going great toe and dorsiflexion and fanning of the other toes. This is an important indication of UMN disease.
Pathological reflexes - frontal release signs- snout, root, palmomental
These patterned behavior reflexes appear when there is damage to the frontal lobes, which normally inhibits these primitive reflexes.
A snout reflex occurs when a tongue blade is pressed on the lips and there is pouting of the lips.
A root reflex occurs when gently stroking the lateral upper lip causes the mouth to moves toward the stimuli.
A palmomental reflex occurs when stroking the palm of the hand causes the ipsilateral mentalis muscle of the lower lip to contract.
Strength testing using squat & rise, heel & toe
This patient has proximal pelvic girdle weakness which is demonstrated by his using his hands to climb the wall and then pushing on his thighs to get his trunk upright. When a patient uses his hands to climb up his legs to get to a standing position is this called a Gowers' sign.