Biomedical subjects

P Lycett

Publications and source records attributed to P Lycett.

3 recordsLinked to original sources

PubMed1978

Recovery nystagmus.

Secondary nystagmus is frequently seen following cessation of prolonged unidirectional vestibular stimulation. It is explained on the basis of an adaptation during the application of the stimulus which leads to an apparent stimulus in the opposite direction when the stimulus is removed. The same phenomenon would be expected with vestibular disease when after a period of adaptation to the vestibular asymmetry, the affected ear recovers some or all of its function. The seondary nystagmus in this instance beats toward the affected ear and has been termed recovery nystagmus because it is generated by recovery of function. Two cases with recovery nystagmus following acute attacks of vertigo are presented.

Adaptation, Physiological↗

PubMed1977

Vestibular dysfunction associated with benign paroxysmal vertigo.

Benign paroxysmal vertigo (BPV) is a clinical syndrome of vestibular origin although generally no evidence of vestibular dysfunction can be demonstrated with conventional tests. In a review of 1350 consecutive dizzy patients, there were 125 with BPV and of these, 33 underwent a quantitative rotational test of vestibular function. The rotational results showed reduces vestibular system gain for these BPV patients. In addition, they could be subdivided on the basis of a normal or shorter cupular time constant (Tc). Separation of patients into diagnostic categories revealed that those categorized as cupulolithiasis and viral labyrinthitis had a normal Tc range and those categorized as trauma and idiopathic had a short Tc. The reduced gain and short Tc in the latter group suggest hair cell and/or nerve damage since these same changes occur in patients with destructive peripheral vestibular disease.

Adult↗

PubMed1976

A quantitative rotational test of vestibular function.

This paper describes a quantitative vestibular test in which the stimulus is a constant angular acceleration of 3 degrees/sec2 for 80 sec. The nystagmus output is plotted as cumulative slow phase eye displacement against time and is displayed on an oscilloscope screen along with the output from a mathematical model describing vestibulo-oculomotor function. External dials allow one to change the equation constants thereby altering the shape of the model output. Values for equation constants which match the model output to the patient can be read directly from the dials, thus providing a description of the vestibular system under test. Results indicate that vestibular asymmetry (manifest by spontaneous nystagmus is not uncommon in normals, and only when spontaneous nystagmus is coupled with vestibular gain does one get a measure of abnormality. The significance of altered vestibular parameters in certain pathological states is discussed.

Acceleration↗