Strange Reflexes: What They Say About Your Health

What's Normal and What Might Signal Disease

Testing the Babinski relfex on a baby
What are some of the strange reflexes we may have and when are they normal?. Velkoi/iStock Photo

Some reflexes, such as the knee-jerk, are normal. But others are abnormal and may signal a medical condition. Sometimes, the absence of a reflex can be an indication that something might be wrong. Learn more about some of the body's strangest reflexes and what they indicate about your health. 

What Is a Reflex?

A reflex is one way that the body manages critical functions like standing upright without relying on the conscious part of the brain.

Many reflexes don't need to go into the brain at all but can be managed entirely in the spinal cord.

The most familiar reflex is the knee-jerk: when a doctor taps on the tendon below your knee with a reflex hammer and that leg kicks out. The stimulus (the hammer) results in a signal being sent via a sensory nerve to the spinal cord. From the spinal cord, a response is immediately sent back via a motor nerve, which results in the kick. This communication—from a sensory nerve to the spinal cord and on to a motor (movement) nerve (without going to the brain)—is known as a reflex arc.

Normal vs. Pathological (Abnormal) Reflexes

Many reflexes are normal. For example, the knee-jerk is a normal reflex and the absence of this reflex would be considered abnormal. Many reflexes are normal in a newborn or young child but would be abnormal if found in an adult. Some reflexes can be a sign of disease but also occur fairly often in healthy people without any neurological condition.

In that case, the presence of the reflex has to be weighed with other findings to determine whether there is a problem. 

Strange Reflexes

The body is capable of a plethora of reflexes. Take a closer look at some of the lesser known, weirder—but totally normal—reflexes of the body, below. 

  • The Babinski reflex: One of the more common reflexes that a neurologist may test is the Babinski reflex. In this exam, a neurologist scratches the bottom of your foot with something irritating. In an adult, the toes then normally curl down. Yet in children, until around the age of two, and in adults with a brain or spinal cord injury, the toes instead go up and fan out. In adults, this may signal a problem such as a stroke, a brain tumor, meningitis, or a spinal cord injury.

  • The snout reflex: The snout reflex is a normal childhood reflex that usually vanishes with age, but may come back if the frontal lobes of the brain are damaged. A physician taps lightly on your upper lip with your lips held together and watches for a response. A response that's abnormal in adults (but normal in babies) is to have the lips purse, giving the appearance of a pig's snout. It can be unilateral (on one side) or bilateral (on both sides.) The reflex is probably designed to help a baby suck. In an adult, this response often indicates a frontal lobe problem such as frontal lobe head trauma or a frontal lobe stroke.

  • The glabellar reflex (Myerson's sign): The area above the nose on the forehead and between the eyes is called the glabella. When tapped on the glabella, most people blink. Normally people stop blinking after a few taps, but if the blinking persists, it's called Myerson's sign, which often means that there's some brain abnormality. This reflex is most commonly seen in people with Parkinson's disease.

  • The palomental reflex: The palomental reflux is tested by scratching the palm of the hand and watching to see if the chin quivers. This is an abnormal reflex that may signify damage to the brain. It may be present from birth (congenital) in children with Down syndrome but is also seen in adults with Alzheimer's disease. Along with the snout reflex, the palomental reflex indicates that there may be damage to the frontal lobes of the brain. This reflex, however, is often present in people without any pathology (who are healthy.)

  • The anal reflex: The anal reflex may also be called the anal wink, the perineal reflex, or the anocutaneous reflex. It's a normal reflex in which the anal sphincter tightens in response to a local, irritating stimulus such as stroking the skin around the anus. The absence of this reflex may signify disease. If this reflex is absent, it can be a sign of spinal cord damage that affects the pudendal nerve (an efferent nerve at S2 to S4.)

  • The cremasteric reflex: The cremasteric reflex is stimulated by lightly stroking the inside of the thigh. In men, this causes the cremaster muscle to contract and the testes to elevate. This reflex can disappear for many reasons, such as damage to the brain or spinal cord (upper and lower motor neuron problems) or non-nervous system related problems like testicular torsion.

  • Clonus: Clonus is a hyperactive reflex. It can be a condition, itself, or it can be caused by another condition. Physicians test this reflex by moving the foot in a certain way. If the patient responds by having a type of repetitive muscle spasm, in which he or she keeps flexing that foot over and over quickly for several seconds, that can be a sign of damage to the brain or spinal cord. One twitch or a few can be normal, but if it goes on for a while, that may be concerning. This spasticity is often a sign of an upper motor neuron disorder such as Huntington's chorea, a brain tumor, meningitis, or a spinal cord injury. Clonus may also be seen in patients with serotonin syndrome, a condition that's characterized by an excess dose of serotonin and is sometimes seen in people who are using anti-depressant medications.

  • Hoffman's reflex: Hoffman's reflex is tested by flicking the middle or ring finger and watching to see if the thumb twitches. This reflex is often present in healthy people, but if the reflex is stronger on one side of the body than the other, it may be a sign of a neurological disorder. The reflex is also known as the finger flexor reflex. A Hoffman's reflex that is stronger on one side of the body often signifies an injury or abnormality above the level of C5 to C6 in the spinal cord. It could be due to multiple sclerosis (MS)amyotrophic lateral sclerosis (ALS) (also known as Lou Gehrig's disease), cervical spine arthritis, myelitis, or a tumor (damage anywhere along the corticospinal or pyramidal tract). The reflex may also be seen in people with anxiety or hyperthyroidism. Doctors tend to think of scans as being more accurate than a physical exam, but this may be one exception. In one study it was found that the Hoffman's reflex was even more accurate than an MRI in finding early spinal cord dysfunction. 

Reflexes Are Abundant

Any muscle can be tested for a reflex so long as there's an accessible tendon. In addition to the ones listed above, there are lots more reflexes in the body—in fact, more than can be easily counted. These reflexes can give valuable clues to neurologists who are trying to determine whether there is a problem with someone's nervous system. Make an appointment with your doctor for an evaluation if you notice any concerning reflex. 

Sources:

Ropper. Adams and Victor's Principles of Neurology, 10e. N.p.: McGraw-Hill, 2014. Print.

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