Photopalpebral Reflex Research Articles

Reponses aux stimulations visuelles dans les etats de coma aigu et de coma chronique

The visual evoked responses (VER) recorded from the midline in bipolar derivations (frontovertex and vertex-occiput) have been averaged in the Mnemotron CAT 400 C in patients in coma dépassé (irreversible coma), in deep acute coma and in chronic coma (41 subjects in all) during EEG investigations. These studies consisted of sequences of 40 flashes repeated every 5 min and for 1–1.5 h in each patient. 1. 1. In coma dépassé (Stage IV in Fischgold and Mathis) the only response which can be averaged is the electroretinogram (ERG). 2. 2. In acute coma (Stage III of Fischgold and Mathis) with a rapidly fatal outcome we find: (a) stereotyping and areactivity of the occipital responses during the same examination; (b) earlier deterioration of the cortical VER than of the spontaneous activity and, in the terminal phase, its extinction always preceding that of the EEG; (c) contamination of the scalp derivations by the ERG, clearly increasing during electro-clinical worsering. 3. 3. In comas which have become chronic: (a) the VER, extremely reduced in the initial stages, can show later recovery, to become fixed, during the third period, with an unchanging stereotyped appearance; (b) during this third period the differentiation between the responses during waking and sleeping become more and more clear. With the eyes open the VER and ERG are either non-existant or considerably reduced, contrasting with the exaggerated photopalpebral reflex. During sleep the photopalpebral reflex is abolished, the ERG increased and the VER facilitated, possibly with a rhythmic after-discharge; (c) stereotyping of the VER is thus maintained in chronic coma but with two modes of expression, one belonging to the state of waking, the other seen during sleep. This differentiation between waking and sleeping is one of the characteristics of passing into the chronic state; (d) there is an over-all agreement between the appearance of the spontaneous EEG and the cortical evoked responses but disagreement appears when the various elements are examined in detail.

Study of the averaged photopalpebral reflex in man.

Study of the averaged photopalpebral reflex in man.

The averaged photopalpebral reflex in man : K. Inanaga and E. Yamaguchi (Kurume City, Japan)

The averaged photopalpebral reflex in man : K. Inanaga and E. Yamaguchi (Kurume City, Japan)