Neurology - Eliciting Deep Tendon and Brainstem Reflexes


LSU Physician Champion - Dr. Jesus Lovera


Deep Tendon Reflexes

A good hammer is essential.
Queen square hammer just needs to be held at the tip of the reed. The flexible reed will do most of the work for you if you let it. NOT TO BE USED IN BABIES
Laska hammer. Hold with two fingers from the tip of the hammer. This is why it has then indentations on both sides.
Tromler hammer hold loosely close to the tip of the hammer.

Practice


This part of the exam requires the most practice. Practice with a healthy volunteer. During your rotation compare your results with attending or resident’s results.
Tap the tendon with a fast tap. Holding your hammer at its full strength and relaxing your wrist will help with this. Do not put your index finger near the head of the hammer.
Tap the tendon not the muscle. The patient must be relaxed and the muscle for the reflex you are testing must be relaxed.

Key reflexes (biceps,triceps, brachioradialis, patellar achillean)

 
Jaw jerk: Have the patient relax their jaw about ⅓ open. Hold the chin between thumb and index with your thumb on the chin. Tap your thumb.
Biceps: Have the patient flex their elbow, palpate the tendon, hit the tendon with your hammer.Leaving your finger on the tendon may help elicit this reflex especially in obese persons.
Triceps: Hold the patients arm at 90degrees with the forearm dangling. Find the tendon proximal to the olecranon. Tap the tendon. Alternative, hold the patient’s hand with your hand. Position the elbow at 90 degrees tap the tendon.
Brachioradialis: Hold the patients arm flexed 90degrees at the elbow. The tendon will be one inch proximal to the radial eminence.
Quadriceps: Feel for the tendon between the rotula and the tibial eminence. With the knee flexed 90 degrees tap the tendon. Tap the tendon gently.
Achillean: Dorsiflex the patients foot 90 degrees at the ankle. Tap the tendon.
Compare the biceps reflex on each side to assess for symmetry; do this for all reflexes. Asymmetric reflexes are always abnormal.

Grading


4+ pathologically brisk or clonus, 3+brisk, 2+normal, 1+ trace but elicitable with maneuvers, 0 Absent. Some people add 5+ for sustained clonus. 1-3 grades are normal if symmetric and all muscles are consistently brisk or decreased.

Maneuvers to increase reflexes

 
Jendrassik maneuver: Have the patient hook both hands and pull as hard as they can while clenching their jaw (useful for lower extremities).
For upper extremities clench the fist of the extremity not being tested.

Spreading

 
Under pathological conditions, eliciting one deep tendon reflex will trigger the reflex in neighboring muscles (finger flexors when stimulating biceps, adductor when stimulating the quadriceps or cross-adductor when eliciting adductor)

Additional reflexesa

 
In principle, a deep tendon reflex could be elicited from any muscle. However, the following reflexes are less reliable or may only be present when hyperreflexia is present.
Finger flexion: Have the patient place their fingers flexed at the MCP joint over your flexed fingers. Tap on your flexed fingers.

Hoffman’s sign: hold the distal falanx of the middle finger between you thumb on the fingernail and index finger below the patient’s finger. Flick the the tip of the finger. This is a sign of hyperreflexia of the upper extremity.

Adductor response (L2-L4):
With the patient sitting and thighs abducted approximately 30 degrees palpate the adductor tendon at its insertion on the adductor tubercle. A brisk response in the adductor of the opposite side (crossed-adductor) is also a sign of hyperreflexia and is usually pathological.




Complex Reflexes: Plantar response Babinski Sign

 
Using moderate firm pressure stroke starting on the lateral aspect of the sole at the heal stroke the lateral aspect of the sole; continue stroking following the edge of the sole until just behind the big toe. Use the wooden side of a cotton tip or break a tongue blade in half. For hygiene it is not recommended to use the tip of your hammer although that is its purpose. Don’t use your car keys either. Babinski sign: Big toe will go up and the other toes will fan out.

Cutaneous abdominal reflex

 
Gently stroke the abdomen near the belly button. The umbilicus will move towards the side being stroked. This is a normal reflex.

Bulbocavernosus

 
The anal sphincter will contract when the head of the penis or clitoris is compressed.

Frontal release signs (abnormal reflexes)

 
Suck reflex: stroke the lips gently with a cotton applicator. Sucking movements will occur in pathological situations.
Snout reflex: gently tap the lips with your hammer. The lips will puck.
Glabellar: gently tap on the patient’s forehead when abnormal blinking should stop after two to three taps.