medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

, pronator drift (also known as pyramidal drift) refers to a pathologic

sign A sign is an object, quality, event, or entity whose presence or occurrence indicates the probable presence or occurrence of something else. A natural sign bears a causal relation to its object—for instance, thunder is a sign of storm, or me ...

seen during a

neurological examination A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired. This typically includes a physical examination and a review of the patient's medical his ...

Jean Alexandre Barré Jean Alexandre Barré (25 May 1880, Nantes – 26 April 1967, Strasbourg) was a French neurologist who in 1916 worked on the identification of Guillain–Barré syndrome, Guillain-Barré-Strohl syndrome, as well as Barré–Liéou syndrome. Biog ...

is credited with having first described it; thus it is sometimes known as the Barré test or sign. A positive result indicates

palsy Palsy is a medical term which refers to various types of paralysisDan Agin, ''More Than Genes: What Science Can Tell Us About Toxic Chemicals, Development, and the Risk to Our Children'' (2009), p. 172. or paresis, often accompanied by weakness and ...

. This sign can appear due to an

upper motor neuron lesion An upper motor neuron lesion (also known as pyramidal insufficiency) Is an injury or abnormality that occurs in the neural pathway above the anterior horn cell of the spinal cord or motor nuclei of the cranial nerves. Conversely, a lower motor ...

Pronator drift. gpnoebook.co.uk. URL
http://www.gpnotebook.co.uk/simplepage.cfm?ID=503709725
Accessed On: October 23, 2008. or various other conditions (including

inborn errors of metabolism Inborn errors of metabolism form a large class of genetic diseases involving congenital disorders of enzyme activities. The majority are due to defects of single genes that code for enzymes that facilitate conversion of various substances ( substr ...

) which include palsy as a symptom.

Description

Assessing for pronator drift helps to detect mild upper limb weakness in a patient who's awake and able to follow directions. Ask the patient to close the eyes, then to stretch out both arms in the appropriate position: Flex the shoulder joint to 90 degrees (45 degrees, if supine) and fully extend the elbow joint. The palms should be facing up (supinated). The patient should maintain this position for 20 to 30 seconds. Observe both arms. If the motor pathway is intact, the arms should remain in this position equally. Patients with a slight weakness in one arm won't be able to keep the affected arm raised, and ultimately the palm may begin to pronate (palm facing down). Pronator drift indicates abnormal function of the corticospinal tract in the contralateral hemisphere. In some patients, the arm may remain supinated but drop lower than the unaffected arm, and the fingers and elbow might flex. The patient is asked to hold both arms at 90 degree flexion and elbows fully extended at shoulder level in front of them, with the palms upwards, and hold the position. If they are unable to maintain the position the result is positive. Closing the eyes accentuates the effect, because the brain is deprived of visual information about the position of the body and must rely on

proprioception Proprioception ( ) is the sense of self-movement, force, and body position. Proprioception is mediated by proprioceptors, a type of sensory receptor, located within muscles, tendons, and joints. Most animals possess multiple subtypes of propri ...

. Tapping on the palm of the outstretched hands can accentuate the effect.

Interpretation

This is a test of upper motor neuron disease. If a forearm

pronate Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

s, with or without downward motion, then the person is said to have pronator drift on that side reflecting a contralateral

pyramidal tract The pyramidal tracts include both the corticobulbar tract and the corticospinal tract. These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (''cort ...

lesion. In the presence of an upper motor neuron lesion, the supinator muscles in the upper limb are weaker than the pronator muscles, and as a result, the arm drifts downward and the palm turns toward the floor. A lesion in the ipsilateral

cerebellum The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or eve ...

or ipsilateral dorsal column usually produces a drift upward, along with slow pronation of the wrist and elbow.

References

External links

Picture of pronator drift test position
- pediatricneurology.com. {{Nervous and musculoskeletal system symptoms and signs Symptoms and signs: Nervous system