Reflex Exam (Deep Tendon Reflexes)

Reflexes are useful for the general internist to perform, but you can’t evaluate them if…

1. You don’t have a hammer.
2. You don’t use proper technique, in which case the reflex will appear to be absent when it is present.
3. If you don’t know what abnormalities to expect and what they mean.

Deep Tendon Reflexes

Root Level 

1. Biceps and Brachioradialis C5/C6
2. Triceps C7 (Note: Some references include C6 OR C8, however C7 is predominantly involved.)
3. Patellar L2-L4
4. Ankle S1

Superficial Reflexes

Corneal reflex (blink reflex)

1. Involuntary blinking in response to corneal stimulation
2. Afferent: nasociliary branch of ophthalmic branch (V1) of trigeminal nerve (5th nerve)
3. Efferent: facial nerve (7th nerve)

Abdominal reflex

1. Contraction of superficial abdominal muscles when stroking abdomen lightly
2. Significant if asymmetric–usually signifies a UMN lesion on the absent side.

Cremaster reflex

1. Contraction of cremaster muscle (that will pull up the scrotum/testis) after stroking the same side of superior/inner thigh
2. Absent with:
3. testicular torsion
4. upper/lower motor neuron lesions
5. L1/L2 spinal cord injury
6. ilioinguinal nerve injury (during hernia repair)

Plantar reflex

1. The plantar reflex can be:
2. Normal (Toes down-going)
3. Absent
4. Abnormal or "Babinski Present"
5. Note: It is incorrect to say ‘negative Babinski'

Visceral Reflexes

Anal reflex (anal wink)

1. Reflexive contraction of the external anal sphincter upon stroking the skin around the anus (afferent: pudendal nerve; efferent: S2-S4)

Bulbocavernosus reflex

1. Anal sphincter contraction in response to squeezing the glans penis or tugging on an indwelling Foley catheter
2. Reflex mediated by S2-4 and used in patients with spinal cord injury

Deep Tendon Reflex Scale

We are not big believers in grading reflexes (grading muscle power is much more useful). Nevertheless, if you need something beyond “absent,” “present,” “brisk,” or “hyperactive” then use below. If you have a hyperactive reflex don’t forget to look for clonus.

1. 0: absent reflex
2. 1+: trace, or seen only with reinforcement
3. 2+: normal
4. 3+: brisk
5. 4+: non-sustained clonus
6. 5+: sustained clonus

Two articles on the history of the reflex hammer:

History of Reflex Hammers by Douglas J. Lanska, 1989

The Short History of the Reflex Hammer by Francisco Pinto, 2003