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Reflex Testing

 Reflex Testing

Deep tendon reflex testing (DTRs), myotatic reflexes, provide information about the integrity of the cervical and lumbar nerve roots and their afferent (from the periphery to the CNS) and efferent (from the CNS to the periphery) pathways.

Reflex testing is limited because not all nerve roots have an associated Deep tendon reflex.

The impact of the reflex hammer on the muscle tendon stretches the tendon, stimulating Golgi tendon organs and muscle spindles. These receptors send a signal to the spinal cord indicating that the muscle is being stretched. In turn, the spinal cord sends a motor impulse to the muscle instructing it to fire and therefore take the stretch off of the muscle.

See Also: Hoffman Sign
Deep Tendon Reflex

Deep Tendon Reflex Grading

A standard scale for grading DTRs is used. Differences in reflexes on the left and right sides are more significant than hyper- or hyporeflexia occurring on both sides (if a spinal cord or brain pathology is not suspected). Because of natural variability, the results of reflex testing should be interpreted in light of other examination findings. Increased response to a reflex testing indicates an upper motor neuron lesion, while decreased responses could signify a lower motor neuron lesion.

Upper motor neuron lesion: A lesion proximal to the anterior horn of the spinal cord that results in paralysis and loss of voluntary movement, spasticity, sensory loss, and pathological reflexes.
Lower motor neuron lesion: A lesion of the anterior horn of the spinal cord, nerve roots, or peripheral nerves resulting in decreased reflexes, flaccid paralysis, and atrophy.

GradeResponse
0No reflex elicited
+1Hyporeflexia: Reflex elicited with reinforcement (precontracting the muscle)
+2Normal response
+3Hyperreflexia (brisk)
+4Hyperactive with clonus
Deep Tendon Reflex Grading

Clonus: Neuromuscular activity in the skeletal muscle marked by rapidly alternating involuntary contraction followed by relaxation.

How do you perform the Deep tendon reflex?

DTRs are assessed with the target muscle/ tendon on slight stretch and relaxed. The patient should be instructed to look away from the target site. The tendon should be struck briskly by the reflex hammer and the reaction noted.

The reflex should be elicited multiple times, with any change in response noted. In some patients, eliciting a reflexive response is difficult. For these individuals, the technique of having the patient contract a muscle away from the target area, the Jendrassik maneuver, may be helpful. All of the reflexes in the extremity being tested should be assessed and compared with the same reflex in the opposite extremity.

For example, in a patient who exhibits poor muscle tone, a reflex that is elicited with reinforcement might be assessed as abnormal. However, further assessment would reveal that all of the remaining reflexes are also grade 1. Therefore, this is the baseline assessment naturally found in this individual.

Jendrassik maneuver
Jendrassik maneuver

Nerve Root Specific Reflex Testing

C5 Nerve Root Reflex:

Reflex NameBiceps Reflex
MuscleBiceps brachii
Patient PositionSeated looking away from the tested side
Position of ExaminerStanding to the side of the patient, cradling the forearm with the thumb placed over the tendon
Evaluative ProcedureThe thumb is tapped with the reflex hammer.
InnervationMusculocutaneous nerve
Nerve RootC5, C6
Biceps Reflex
Biceps Reflex

C6 Nerve Root Reflex

Reflex NameBrachioradialis Reflex
MuscleBrachioradialis
Patient PositionSeated looking away from the tested side, The elbow is passively flexed to between 60° and 90°.
Position of ExaminerCradling the patient’s arm
Evaluative ProcedureThe distal portion of the brachioradialis tendon is tapped with the reflex hammer. The proximal tendon may also be used.
InnervationRadial nerve
Nerve RootC5, C6
Brachioradialis Reflex
Brachioradialis Reflex

C7 Nerve Root Reflex

Reflex NameTriceps Reflex
MuscleTriceps brachii
Patient PositionSeated looking away from the tested side
Position of ExaminerSupporting the patient’s shoulder abducted to 90° and the elbow flexed to 90°
Evaluative ProcedureThe distal triceps brachii tendon is tapped with the reflex hammer.
InnervationRadial nerve
Nerve Root(C6), C7, C8
Triceps Reflex
Triceps Reflex

L4 Nerve Root Reflex

Reflex NamePatellar reflex
MusclePatellar tendon (quadriceps femoris)
Patient PositionSitting with the knees flexed over the end of the table looking away from the tested side
Position of ExaminerStanding or seated to the side of the patient
Evaluative ProcedureThe patellar tendon is tapped with the reflex hammer.
InnervationFemoral nerve
Nerve Root(L2), L3, L4
Patellar reflex
Patellar reflex

L5 Nerve Root Reflex (Tibialis Posterior)

Reflex NameTibialis Posterior Reflex
MuscleTibialis posterior
Patient PositionSide-lying on test side, The test foot is off the edge of the table
Position of ExaminerStanding or seated to the side of the patient
Evaluative ProcedureThe tibialis posterior tendon is tapped with the reflex hammer posteriorly and just proximal to the medial malleolus.
InnervationTibial nerve
Nerve RootL5, (L4, S1)
Tibialis Posterior Reflex
Tibialis Posterior Reflex

L5 Nerve Root Reflex (Medial hamstrings)

Reflex NameHamstrings Reflex
MuscleMedial hamstrings
Patient PositionProne with the knee slightly flexed looking away from the tested side
Position of ExaminerStanding or seated to the side of the patient. The thumb or finger is placed over the semitendinosus tendon immediately superior to the medial joint line.
Evaluative ProcedureThe finger is tapped with the reflex hammer.
InnervationTibial nerve
Nerve RootL5, S1, (S2)
See Also: Lumbar Spine Nerve Roots
Hamstrings Reflex
Hamstrings Reflex

S1 Nerve Root Reflex

Reflex NameAchilles Tendon Reflex
MuscleAchilles tendon (triceps surae muscle group)
Patient PositionProne with the feet off the edge of the table
Position of ExaminerSeated or standing next to the patient, supporting the foot in its neutral position
Evaluative ProcedureThe Achilles tendon is tapped with a reflex hammer.
InnervationTibial
Nerve RootS1, S2
See Also: S1 Nerve Root
Achilles Tendon Reflex
Achilles Tendon Reflex

S2 Nerve Root Reflex

Reflex NameBiceps Femoris Reflex
MuscleBiceps femoris
Patient PositionProne with the knee flexed to approximately 20°
Position of ExaminerStanding next to the patient. The thumb is placed over the biceps femoris tendon just proximal to the joint line.
Evaluative ProcedureThe thumb is tapped with a reflex hammer.
InnervationTibial, common peroneal
Nerve RootL5, S1, S2, (S3)
Biceps Femoris Reflex
Biceps Femoris Reflex

References

  1. Dick JP. The deep tendon and the abdominal reflexes. J Neurol Neurosurg Psychiatry. 2003 Feb;74(2):150-3. doi: 10.1136/jnnp.74.2.150. PMID: 12531937; PMCID: PMC1738294.
  2. Reese, NB: Techniques of the sensory examination. In Muscle and Sensory Testing, ed 2. St. Louis, MO: Elsevier Saunders, 2005, p 522.

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