The Unipedal Stance Test or the Single Leg Stance Test is an assessment used to evaluate static postural and balance control.
If an individual experiences difficulty in balancing with open eyes, it often indicates a problem with the vestibular function, linking the brain and the ear. (Shutterstock)
Balancing on one foot might seem like child’s play, but sometimes when adults engage in it, it may prove to be difficult.
If a person is unable to balance their body while standing on one foot, it takes on a new significance: It becomes a reflection of one’s physical well-being.
Medical professionals have designed a test based on this to gather more information about a person’s health.
The Unipedal Stance Test (UPST) — also known as the Single Leg Stance Test — is an assessment used to evaluate static postural and balance control.
During the test, the patient needs to stand on one leg, unassisted, with hands on the hips. The time frame starting from the moment one foot leaves the ground and till it touches the ground again will be recorded.
“There is a significant age-dependent decrease in the ability to stand on one leg with both the eyes open and closed. UPST times are not gender specific (they are similar in men and women), with the eyes open condition always resulting in significantly longer UPST times than eyes closed,” Hyderabad-based neurologist Dr Sudhir Kumar told South First.
He said maintaining balance with open eyes appears deceptively simple, as it allows for a clear visual understanding of one’s surroundings.
In essence, achieving stability while standing requires essential components, assuming the patient possesses a standard level of strength in comparison to an individual with paralysis.
Firstly, grounding oneself involves obtaining sensory feedback from the ground. The sensory nerves in our feet play a crucial role in providing this fortunate ability to perceive ground sensations.
Secondly, the alignment of our feet and joints, in relation to joint movements, contributes significantly to our ability to stand effectively.
Additionally, there is a crucial element of perception, such as the awareness that occurs when one runs a finger over a surface or moves their toes. However, in individuals with damaged sensory nerve fibres, this perceptual ability may be compromised, a condition known technically as proprioception.
Proprioception, or the ability to sense the ground through joint and foot movements, becomes impaired in instances like diabetic neuropathy, where numbness is present.
The third component involves the nerve fibres related to balance, commonly referred to as the vestibular system. The vestibular nerve, originating from the brain and connecting to the ear, is integral for maintaining balance, especially during actions like opening and closing the eyes.
Dr Kumar said that if an individual experiences difficulty in balancing with open eyes, it often indicates a problem with the vestibular function, linking the brain and the ear.
On the other hand, if a person can stand steadily with eyes open but struggles upon closing them, the issue likely stems from proprioception and compromised sensory nerve fibres.
The initial step in evaluating balance is to consistently begin with an assessment conducted with the eyes open. The purpose is to ascertain whether the individual’s balance falls within the normal range. If the performance is deemed satisfactory under these conditions, the subsequent instruction is to have the person close their eyes.
“To discern the specific pathway implicated, observe the person’s ability to stand with closed eyes. If standing becomes problematic under these circumstances, it indicates a sensory pathway issue. Conversely, if the issue arises only when eyes are open, it suggests a physical problem, potentially associated with vitamin B12 deficiency. Moreover, if the problem surfaces solely when eyes are closed, it points toward a sensory pathway concern related to the sensory nerves in the feet, with vitamin B12 deficiency and diabetes being the most common culprits,” said Dr Kumar.
In the case of an individual who was previously stable and able to maintain normal balance but encounters difficulty when eyes are closed, the issue is likely rooted in proprioception.
Proprioception, a sensory facet of balance, initiates its pathway from the skin, involving the detection of sensation, joint position, and the transmission of signals through nerve fibres to the spinal cord.
Even in cases where there is a spinal cord ailment, as often observed in individuals with vitamin B12 deficiency leading to subacute combined degeneration, the impact extends beyond sensory nerves to affect the spinal cord’s posterior columns. The telltale signs often encompass challenges related to joint position and sensation.
Considering other potential causes, such as syphilis — a once injective sexually transmitted disease — and HIV, which may lead to HIV-related myelopathy, the three primary conditions to focus on for practical purposes are vitamin B12 deficiency affecting the spinal cord and posterior columns, and diabetic neuropathy as the prevalent cause for impaired sensory fibres in the feet.
Research has shown that if a person cannot stand on one leg, it may indicate several health issues related to balance and postural control. The Unipedal Stance Test is a valuable tool to assess static postural control and balance, and its inability can suggest the following:
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