Differentiation of balance deficits through examination of selected components of static stabilometry.

Stabilometry, which measures the body's center of pressure (COP) movements, during relaxed standing, has been used to distinguish individuals with vestibular and neurologic dysfunctions from normal subjects. The purpose of this study was to determine whether mathematical differences in the magnitudes of the COP obtained from six somatosensory testing conditions could be used to discriminate between different types of balance deficits. Stabilometry measures, using a fixed force platform, were obtained from normal (N = 52) and dizzy (N = 149), peripheral vestibular dysfunction (PVD), post-concussion syndrome (PCS), psychogenic (PSG), and unknown/undetermined etiology (UNK). The data significantly differentiated CVD, PVD and PSG patients from normals and between some of the dizzy groups: CVD versus PVD, PCS; and PSG versus CVD, PVD, PCS and UNK. The measures of anterior-posterior COP movements provided the greatest discrimination.

Stabilometry in balance assessment of dizzy and normal subjects.

Normal adults and patients referred to the Dizzy Clinic at the Medical College of Ohio had their standing balance assessed during combinations of normal and altered visual and somatosensory orientation conditions using a fixed-force platform to measure center-of-pressure translations. Significant differences were identified between normal subjects and dizzy patients, depending on the particular diagnostic category, the sensory condition tested, and the particular sway component being measured. Patients with central and peripheral vestibular dysfunctions had significantly greater sway than all other categories in most test conditions, especially with eyes closed and with a visual conflict dome while standing on a foam surface. The central vestibular dysfunction and peripheral vestibular dysfunction groups could be differentiated statistically under eyes-closed and visual conflict-foam conditions. The normal and psychogenic groups could not be differentiated statistically for any test conditions except one: there was significantly greater mean anterior/posterior sway displacement in the psychogenic group compared with all other diagnostic categories for the eyes-open foam test condition. Our results indicate that static stabilometry recordings of postural sway can be used to evaluate and quantify a dizzy patient's ability to receive and process vestibular, visual, and somatosensory-proprioceptive cues for postural stability. It can also be used to monitor patients with vestibular disorders and to document their responses to rehabilitation programs.

Closed versus open kinematic chain measurements of subtalar joint eversion: implications for clinical practice.

Subtalar joint (STJ) range of motion is most critical during the support phase of the gait cycle. The purpose of this study was to determine what differences exist between measures of maximal STJ eversion in open chain and closed chain positions. STJ eversion as a component of STJ pronation was measured in nonweightbearing (NWB) and full weightbearing (WB) positions on 17 subjects who had no significant biomechanical or orthopaedic abnormality. STJ WB eversion was significantly greater than NWB passive ROM. These results indicate that accurate assessment of STJ eversion as a component of pronation requires measurement in a functional WB position as well as in a NWB position. Rehabilitation of persons with lower quarter injuries or disabilities require assessment of ROM in WB positions so that a more accurate and complete evaluation can be done allowing the clinician to make an appropriate diagnosis and treatment.J Orthop Sports Phys Ther 1988;9(9):310-314.

Regulatory mechanisms for substance P in the dorsal horn during a nociceptive stimulus: axoplasmic transport vs electrical activity.

Substance P (SP) is believed to be a neuromediator of nociception in the dorsal horn of the spinal cord. SP precursor is synthesized in the dorsal root ganglia (DRG) and transported via axoplasmic transport to the nerve terminal where it is stored and released as SP. The chemical nociceptive stimulus, formalin, when injected into the hindpaw causes an increase in the level of SP in the dorsal horn. This increase in SP may be the result of increased electrical activity due to activation of free nerve endings or the transport of some chemical or trophic signal to the DRG or to the central terminal. This study investigates the mechanism of the SP increase during the formalin stimulus. Rats were anesthetized and a laminectomy performed. In some experiments the sciatic nerve was exposed. Agar gel pads containing either colchicine or tetrodotoxin (TTX) were applied to the dorsal root or sciatic nerve prior to the injection of 5% formalin or saline into the hindpaw. Electrical activity across the dorsal root distal to the gel pad was monitored to determine the effects of colchicine and TTX on the nerve. Sixty min after the injection into the hindpaw, the animal was perfused and the lumbar spinal cord removed. Ten-micron frozen sections were stained for SP. It was found that the formalin-evoked increase in SP could be partially blocked by either colchicine or TTX applied to the dorsal root and completely blocked by the application of both agents together. TTX or colchicine applied to the sciatic nerve completely blocked the formalin-evoked increase in SP.(ABSTRACT TRUNCATED AT 250 WORDS)

Increase in substance P in the dorsal horn during a chemogenic nociceptive stimulus.

Substance P has been implicated as a neuromediator of nociception in the dorsal horn of the spinal cord. This is the first report of quantitative increases in substance P following an acute nociceptive stimulus. Female Wistar rats were injected subcutaneously in the plantar aspect of the right hindpaw with 5% formalin. Substance P levels were determined by quantitative immunohistochemistry 1 h after the injection. The present results show that substance P levels in the upper two laminae of the ipsi-and contralateral dorsal horn were significantly increased 1 h after the formalin injection. These results suggest a direct functional relationship between substance P levels in the upper dorsal horn and an acute chemogenic nociceptive stimulus.

Morphine blocks the increase in acid phosphatase in the substantia gelatinosa during pain.

Acid phosphatase activity in the rat substantia gelatinosa has been shown to increase in response to a formalin-induced painful stimulus. In the rat the substantia gelatinosa is the location of the first synapse in the pain pathway. One site of morphine's analgesic effect is at this first synapse. The present study shows that morphine blocks the previously observed increase in acid phosphatase activity during a painful stimulus. Naloxone antagonizes the morphine effect. These results point to a possible functional role of acid phosphatase in the afferent transmission of pain signals.

Changes in acid phosphatase activity in the substantia gelatinosa in response to pain.

Two-day and 15-day-old offspring of capsaicin-pretreated Wistar rats were given subcutaneous injections of a 5% formalin solution to the dorsal aspect of the right forepaw. One hour after injection, acid phosphatase activity of the substantia gelatinosa of formalin/capsaicin cervical sections was significantly greater bilaterally than in saline/capsaicin 15-day-old animals. In 2-day-old animals the formalin/control right cervical sections had significantly higher acid phosphatase activity than saline/control. These results are further support for a direct functional relation between activity in the substantia gelatinosa and chemogenic pain stimulus.

Effects of vestibular stimulation in seizure-prone children. An EEG study.

Concern that vestibular stimulation may induce seizures in seizure-prone children has been based on hearsay and unconfirmed clinical impressions of practicing therapists. To clarify this issue, we took electroencephalographic recordings of seizure-prone children before, during, and after specific vestibular stimulation. Ten children with seizure histories, 5, to 15 years of age, were exposed to warm and cold caloric vestibular stimuli. Electroencephalographic activity was recorded before, during, and after each vestibular stimulus; recordings were rated and compared prevestibular and postvestibular stimulation. Electronystagmographic recordings were also taken. Results show that vestibular stimulation does not accentuate the abnormal brain wave pattern in seizure-prone children. Six of 10 subjects had a significant reduction in paroxysmal activity (p less than .02). Possible explanations for clinical reports of vestibular induced seizures are given, with suggestions for precautions when applying vestibular stimulation to seizure-prone children.

Effects of vestibular stimulation on nystagmus response and motor performance in the developmentally delayed infant.

The effects were studied of 10 days' exposure to daily repetitive, specific vestibular stimulation on motor performance of children with Down's syndrome and normal children. A quantitative assessment of vestibular function was made in these children including the habituation response of postrotatory nystagmus. Control groups were included. Both the children with Down's syndrome and the normal children who received vestibular therapy demonstrated positive effects when evaluated using a quantitative motor skills assessment test. Control and treatment children showed vestibular habituation, with treatment children evidencing the greater change. This change may reflect the acquisition of an increased level of central nervous system inhibitory control.