모터 시험 II

Reflex, coordination and gait examinations form an integral component of motor assessment, and may help in pinpointing the location of the lesion or recognize a movement disorder. A reflex arch is a simple circuit that involves activation of a sensory neuron that travels to the spinal cord and in turn activates a motor neuron, which causes a response. Whereas, coordination of movements and gait has complex multi-level regulation and requires an integrated function of different components of the nervous system.

In this presentation, we’ll first review the types of reflexes. Then we’ll go over the method of testing them in upper and lower extremities. Lastly, we will review how one should evaluate coordination and gait to diagnose neurological disorders.

Let’s begin by discussing the two main types of reflexes. A deep tendon reflex, or DTR, is usually tested using a reflex hammer. It results from the stimulation of a stretch-sensitive afferent from a neuromuscular spindle, which, in turn stimulates a motor nerve leading to a muscle contraction. There is a wide variation in the magnitude of this reflex response, which can be graded on a scale of 0 to 4, where zero represents no response, two is normal, and four is heightened response with clonus.

Although the DTR of nearly any skeletal muscle could be examined, the reflexes are routinely tested for the brachioradialis, biceps, and triceps muscles in the upper extremities, and at the patellar, and Achilles tendons in the lower extremities. These reflexes may be increased with chronic upper motor neuron lesions, and decreased with lower neuron lesions as well as nerve and muscle disorders. A common method of recording the DTR findings is by using a stick figure diagram where each number represents the grade of response observed at the corresponding location.

The other type “superficial reflex” is a segmental response that results from the stimulation of a specific sensory input, like the blink reflex, or the abdominal reflex. These are graded as either present or absent. Another superficial reflex commonly tested is the plantar reflex, which is elicited by stroking the lateral aspect of the sole. The normal adult response is plantar flexion of the big toe. Although, in infants less than 2 years of age the toe will dorsiflex. And, in adults with damage to the pyramidal system, the response is similar to infants, where the toe becomes “upgoing”. This abnormal response in adults is known as a Babinski sign, named after its discoverer- the French neurologist ‘Joseph Babinski’.

Now that we have an understanding of the different reflexes, let’s review how to test them in the upper and lower extremities. For deep tendon reflexes, one should know how to properly use the reflex hammer. The instrument should be held loosely and guided by the thumb and the index finger. The swing should be carried out in an arc-like fashion making use of the angular momentum, while keeping the wrist loose.

Begin the exam at the biceps muscle. Ask the patient to relax and pronate their forearm halfway between flexion and extension. It is important to pay close attention to the position of the limbs before all the reflex tests. This helps in ensuring that the muscle is in a relaxed state. Then, palpate for biceps tendon in the antecubital fossa and place one finger on the tendon.

Next, tap the finger with the reflex hammer and observe for biceps muscle contraction. The elbow may flex slightly or the muscle may simply contract without other observable movement. Next, test the brachioradialis reflex. Have the patient place their forearm in a semiflexion, semipronation position. Place your finger on the brachioradialis tendon about 1- 2 inches above the wrist crease. Then using the broad end of the hammer, tap your finger, and observe for flexion at the elbow and supination of the wrist.

After that, test the triceps reflex. Instruct the patient to bend their elbow same way as for the biceps reflex and pull the arm toward their chest. Then tap the triceps tendon two inches above the elbow, and observe for contraction of the triceps muscle and extension at the elbow. Another method to evaluate triceps reflex is to have the patient hang their arm over your arm. Make sure that the patient is placing their arm’s full weight on yours. Then, in this position, tap the triceps tendon, and observe for triceps muscle contraction and elbow extension.

Subsequently, move on to testing the lower extremity reflexes. Begin with the patellar reflex. Ensure that the patient’s legs are dangling off the table. Place your hand on the quadriceps, and strike the patellar tendon firmly with the pointed edge of the hammer. Feel for contraction of the quadriceps and observe for extension at the knee. If the patient is lying supine, place the arm under the knee such that the knee is flexed to slightly less than 90°. Then strike with the hammer below the patella and look for quadriceps contraction and knee extension.

Next, test the Achilles Reflex. In seated position, place your hand under the patient’s foot and partially dorsiflex the ankle. Then with the hammer’s wide end, tap the Achilles tendon just above the insertion on the posterior aspect of the calcaneus, and observe for calf muscles contraction and plantar flexion at the ankle. If the patient is lying down, hold the foot in a partially dorsiflexed position with the medial malleolus facing the ceiling. The knee should be flexed and lying to the side. Then, strike the Achilles tendon directly and watch the muscles of the calf contract and feel for plantar flexion at the foot. If the Achilles reflex is brisk, assess for ankle clonus. Ask the patient to dorsiflex the ankle actively, and hold the foot in that position. Observe for clonus, which is a rhythmic muscle contraction. More than 3 beats of clonus or any asymmetry between feet is abnormal.

Lastly, examine the superficial plantar reflex. With the stem of the hammer gently stroke the bottom of the foot starting laterally, near the heel, and moving up and across the ball of the foot. A normal response would be the big toe moving downward. If no response from the patient, then increase the pressure. As mentioned before, if there is a disorder of the pyramidal tract or upper motor neuron, the big toe will extend and the other toes will fan out. This is referred to as the Babinski sign.

Now let’s review coordination testing, which includes evaluation of rapid alternating movements and point-to-point coordination, both of which can be altered as a result of cerebellar dysfunction. Begin with rapid alternating movements, ask the patient to slap the palm of the hand on their thigh, then turn it over and strike the back of the hand. Instruct them to repeat the same sequence several times. Encourage doing it faster, while you assess for rhythmicity. Then, ask the patient to repeat it on the other side and compare.

Next, ask the patient to tap the tip of their index finger against the distal joint of their thumb and demonstrate the repeated motion you would like them to achieve. Have the patient perform movement with one hand, then the other. Compare how smoothly the task is done with each hand, assessing for speed and rhythm. Patients are often a bit slower performing both these tasks on their non-dominant side. Inability to perform smooth rapid alternating movements due to a cerebellar disease is called dysdiadochokinesia.

For the last alternating movements test, instruct the patient to tap the ball of their foot against the floor in a rhythmic fashion, as if to music. Have the patient repeat the movement with the opposite foot and compare sides. Normally, the movement should be rhythmic and performed without any difficulty.

Moving to point-to-point coordination testing. First test is called the finger to nose test. Have the patient use their index finger to touch your finger and then their own nose. Have them repeat the task and encourage doing it faster. In addition, move your finger as the patient performs the movement, making the patient search for the target, while you assess the accuracy, rapidity, and smoothness of the actions. Ask the patient to repeat the exercise with their opposite hand. Observe for signs of cerebellar disease, such as side-to-side movements when approaching the target known as dysmetria, or an intention tremor.

The last coordination test is called the “heel-to-knee-to-shin test”. Have the patient lie down, and ask them to tap the right heel in the region under the left knee, and then run the heel up and down the shin. Have the patient repeat the movement on the opposite side. Assess for signs of dysmetria and weakness.

The final few tests in motor assessment involve careful examination of the patient’s gait. This can help a clinician screen for problems including weakness, movement disorders, spasticity, and cerebellar disease. One should remember that at times, the only sign of a serious neurologic disorder is an impaired gait.

To assess gait, instruct the patient to sit down and then stand up. Note the ability to maintain a balanced and upright posture. Next, ask the patient to walk up and down the examination room. Observe as they walk. Look for the symmetrical swing of the arms; the rhythm of the gait including equal transit time of each leg; signs of spasticity, such as circumduction; and any abnormalities like a tremor or choreiform movements. Note if the patient turns in a smooth motion or in multiple small steps, which may be a sign of a Parkinson’s disease.

Specific gait patterns can reflect certain conditions. For example, patients with unilateral weakness and spasticity may hold the affected lower limb stiffly to keep it extended, and drag the limb around the body in a circumducting pattern when they walk. This is know as the hemiparetic gait. Another type is diplegic gait, where both sides are affected and a “scissoring” adductor pattern is observed in both legs. A patient with foot drop, that is with an inability to dorsiflex of foot or toes due to muscle or nerve damage, will tend to lift the affected foot high; this is termed as steppage gait. A parkinsonian gait is characterized by small shuffling steps and a general slowness of movement. Patients with this disease may have difficulty starting, but also have difficulty stopping after starting, and may feel propelled forward.

Other than these general observations, there are a few specific tests to assess a patient’s gait. For example, heel and toe walking. Walking on the toes tests plantar flexion and, walking on the heels assesses the strength of dorsiflexion at the ankles, which helps screen for weakness as may be seen in patients with a foot drop. Next, instruct the patient to tandem walk in a straight line, touching the heel of one foot to the toe of the other foot like they are walking on a tightrope. Inability to walk this way with balance and coordination may be a sign of cerebellar dysfunction.

Lastly, conduct the Romberg test. Ask the patient to place their feet together, stand straight and maintain their balance. Inability to maintain a stable position with eyes open may indicate cerebellar dysfunction. If the patient can maintain their balance, then ask them to close their eyes. Be prepared to steady the patient if necessary. Note the ability to maintain balance with eyes closed. Romberg sign is considered positive when the patient can maintain a stable, straight position with their eyes open, but exhibits instability – that is excessive sway or falling to on one side – with their eyes closed. It is a sign of a proprioception disorder.

You have just watched a JoVE’s Clinical Skill’s video on reflex, coordination and gait testing. In this presentation, we revisited the types of reflexes that can be tested during a clinical encounter, and then reviewed the maneuvers involved in coordination and gait testing. You should now have a better understanding of the purpose behind these tests, and how to interpret the findings from this portion of the exam, to reach a differential diagnoses in cases of neurological disorders. As always, thanks for watching!