![Sample our Medicine, Dentistry, Nursing & Allied Health journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5944/TOC-Subject-Sample-2021-Medicine-Dentistry-Nursing-Allied-Health.jpg"})
Abstract
Electrical impedance plethysmography has been applied to the vertebral arteries. By this method the tissue impedance which reflects volume changes, caused especially by the pulse wave, is recorded. A reduced pulsative arterial blood flow results in smaller impedance variations with each pulse wave. Special electrodes for placing against the posterior pharyngeal wall at the level of C2 have been constructed, and an attempt has been made to determine the optimal positions for skin electrodes when the head is in different positions.
In normal persons rotation of the head when in the sitting or supine position does not give rise to changes in the impedance compared with the initial positions. With the head in the hanging position, especially when it is rotated in the direction opposite to the artery being studied, a smaller impedance decrease at each pulse wave than in other positions is normally recorded. This should indicate that some compression of the vertebral artery of one side is, in a certain position of the head, a normally occurring phenomenon.
In patients with a clinical cervical syndrome, low pulse wave amplitudes simultaneous with nystagmus have been recorded. The latter can be regarded as an expression of brain-stem ischaemia, caused here by compression of the vertebral artery in association with a defective compensation via the circle of Willis.