Biomedical subjects

K Hitouji

Publications and source records attributed to K Hitouji.

6 recordsLinked to original sources

PubMed2001

Vertical semicircular canal function: a study in patients with benign paroxysmal positional vertigo.

A pendular rotation test in a head-tilted position (60 degrees backwards and rotated 45 degrees to either the right or left) was performed in 7 patients with benign paroxysmal positional vertigo (BPPV). Patients were rotated 360 degrees at a frequency of 0.1 Hz (maximum speed 114 degrees/s). The excitability of vertical semicircular canals was evaluated using this test procedure. Using an infrared CCD camera and a PC, evoked nystagmus was analyzed in order to determine the morbidity of BPPV. A statistically significant difference (p < 0.05) was found in the maximal slow-phase eye velocity between nystagmus from the anterior semicircular canal and nystagmus from the posterior semicircular canal. The excitability of the posterior semicircular canal in the affected ear was lower than that of the anterior semicircular canal. However, when vertigo and nystagmus disappeared, the difference in excitability was improved. The present results indicate some functional deterioration of the posterior semicircular canal in BPPV cases, suggesting the participation of both mechanical (dumping by mass) and organic (peripheral end organ) factors in causing morbidity.

Adult↗

PubMed2000

Does the vertical semicircular canal influence the subjective visual vertical?

The aim of the present study is to evaluate the influence of vertical semicircular canals on the subjective visual vertical (SVV). SVV was measured on conditions with or without the rotatory stimulus in a head-tilted position, 60 deg back-ward and then rotated 45 deg either to the right or left in 7 healthy volunteers. By this procedure, it was possible to evaluate the SVV elicited by the excitability of vertical semicircular canals. SVV was normal on the condition without the rotatory stimulus. However, SVV was abnormal on the condition with the rotatory stimulus, especially, which was much deviated during the posterior canal excited. We conclude that the vertical semicircular canal influences the spatial orientation such as the SVV.

Adult↗

PubMed1999

EMG responses in lower leg muscles elicited by head-taps.

Forehead-taps elicited short-latency motor responses in the lower leg muscle which, together with vestibulocollic reflexes, might contribute to multisensory control of posture. We tested this paradigm in human subjects standing upright in order to determine if the responses differed depending on whether the taps were to the forehead or temporal bone. Forehead-taps elicited short-latency inhibitory EMG responses in both gastrocnemius muscles with a mean latency of 48 to 99 ms. The right or left temporal bone-taps elicited short-latency inhibitory EMG responses in the ipsilateral gastrocnemius muscle of 47 to 77 ms, short-latency excitatory EMG responses in the contralateral gastrocnemius muscle of 46 to 78 ms, and short-latency excitatory EMG responses in the contralateral tibialis anterior muscle of 48 to 78 ms. The temporal bone-taps elicited short-latency inhibitory EMG responses in the ipsilateral gastrocnemius muscle and excitatory EMG responses in the contralateral gastrocnemius muscle, which were thought to be generated by vestibular afferents and convergent with vestibular input for the multisensory control of posture.

Adult↗

PubMed1998

EMG potentials elicited by forehead taps in the sternocleidomastoid muscles and lower leg muscles--a study on patients with vestibular lesions.

The aim of the present study was to determine whether a tap on the forehead evokes a vestibulospinal reflex in the sternocleidomastoid muscles and the lower leg muscles in patients with vestibular lesions. Although first positive-negative short-latency EMG potentials with a mean positive potential peak of about 12.6 ms and a mean negative potential peak of about 17.3 ms were found in the bilateral sternocleidomastoid muscles in normal subjects, they were lacking in patients with vestibular lesions. The first negative short-latency EMG potentials had a mean latency of 48.3 +/- 3.1 ms (onset) to 98.3 +/- 6.3 ms (end) in both gastrocnemius muscles in normal subjects, but they were delayed in patients with vestibular lesions.

Adult↗

PubMed1998

Evaluation of vertical semicircular canal function by the caloric test--a study on patients with benign paroxysmal positional vertigo.

The morbidity of benign paroxysmal positional vertigo (BPPV) was investigated from the functional standpoint by analyzing nystagmus elicited by the caloric test. As a result of an investigation of the three (horizontal, vertical and torsional) components of the nystagmus elicited by the caloric stimulus (cold water), the vertical nystagmus differed in direction between the left and the right ear in 3 out of the 4 BPPV cases. The vertical nystagmus elicited by the caloric stimulus reflected the functions of the anterior and posterior semicircular canals, and investigation of the difference in function between the anterior and posterior semicircular canal from the direction of the vertical nystagmus appeared to be feasible.

Adult↗

PubMedDate not supplied

Can short-latency vestibulospinal reflexes in lower leg muscles be elicited by tapping the head?

A gentle tap on the forehead evoked short-latency motor responses in the sternocleidomastoid muscle, which may be vestibulocollic reflexes with characteristics similar to those elicited by clicks. We tested this paradigm in subjects standing upright, in order to determine the differential effects of taps on the forehead on the patterns and latencies of spinal stretch and vestibulospinal reflexes, which are important for postural control. Taps on the forehead elicited short-latency inhibitory electromyographic responses in both gastrocnemius muscles with a mean latency of 48.3 +/- 3.1 ms (onset) to 98.3 +/- 6.3 ms (end). Taps on the sternum elicited similar responses from the gastrocnemius muscles, indicating that vestibular stimulation is not essential for eliciting these responses. Both responses may play a role in predetermining the strategy for correcting body perturbations. The actual reflex is probably elicited by somatosensory input from the neck, which converges with vestibular input for the multisensory control of posture.

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