The subjective postural vertical in standing: reliability and normative data for healthy subjects

Area of Science:

• Neuroscience
• Human Physiology
• Biomechanics

Background:

• Impaired verticality perception, often due to lateropulsion or retropulsion, can lead to falls and affect standing ability.
• The subjective postural vertical (SPV) assesses the internal estimate of verticality but is typically measured in a seated position.
• Body orientation representations may differ between sitting and standing due to variations in somatosensory input.

Purpose of the Study:

• To establish a reliable method for assessing the subjective postural vertical (SPV) in a standing position.
• To determine the test-retest and interrater reliability of SPV measurements in standing individuals.
• To provide normative SPV values for healthy adults aged 20-79 years.

Main Methods:

• A novel paradigm using a 3D-moving device (Spacecurl) was employed to measure SPV in standing subjects.
• Test-retest and interrater reliability were assessed in a group of 25 participants.
• Normative data were collected from 60 healthy individuals (10 per decade, ages 20-79).

Main Results:

• SPV measurements in the standing position demonstrated good test-retest and interrater reliability.
• Normative values for SPV were established: -1.7° to 2.3° (sagittal plane) and -1.6° to 1.2° (frontal plane).
• Aging was associated with a backward shift in SPV and increased variability in verticality estimates.

Conclusions:

• Assessing the subjective postural vertical (SPV) while standing is a reliable method.
• The findings support the use of standing SPV assessment for diagnosing patients with impaired verticality perception.
• Further research should explore the diagnostic value of standing SPV compared to existing tools.