the medical term opisthotonos (backward bending tone) means
Opisthotonus Opisthotonus or opisthotonos, from Greek roots, ὄπισθεν, opisthen meaning "behind" and τόνος tonos meaning "tension", is a state of severe hyperextension and spasticity in which an individual's head, neck and spinal column enter into a complete "bridging" or "arching" position.[1][2] This abnormal posturing is an extrapyramidal effect and is caused by spasm of the axial muscles along the spinal column.
Doppler ultrasonography Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to generate imaging of the movement of tissues and body fluids (usually blood)[1], and their relative velocity to the probe. By calculating the frequency shift of a particular sample volume, for example flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized. Color Doppler or color flow Doppler is the presentation of the velocity by color scale. Color Doppler images are generally combined with grayscale (B-mode) images to display duplex ultrasonography images, allowing for simultaneous visualization of the anatomy of the area.