International Journal of Research and Scientific Innovation (IJRSI) |Volume IX, Issue IX, September 2022|ISSN 2321-2705
M-Mode ultrasonography in ocular emergencies
Hadi Khazaei. M.D., M.S., M.C.R.*, G. Seethapathy, MS, MRCS, FRCS Ed, FRCOphth (London), Alireza Mobaseri. M.D., Danesh Khazaei, John D Ng. M.D, M.S
Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA
*Corresponding author
Abstract: M-Mode, or time-motion display, allows a single beam to emit from the ultrasound transducer along a defined track in conjunction with a recorder that captures all motions that occurs along the path. This mode allows high temporal resolution, thus affording the examiner an excellent view of subtle motions. Clinically, this mode is ideal for capturing vessel diameter changes, movement of cardiac valves, and detecting fetal heartbeats.
The use of the M-mode or time-dependent intensity modulated ultrasound technique for ophthalmologic investigations are described here. This technique provides the investigator with a means for monitoring structural changes in the eye during physiologic or pharmacologic experimental conditions, or a combination of both, and is particularly useful in studying optically inaccessible structures. The technique has been used to study accommodation changes in axial length and lens thickness as well as the rate of such changes and to study vascular pulsations and choroidal thickness changes at the rear wall of the eye.
Keywords: Orbital Ultrasonography (USG), Electromyogram (EMG), Visual Evoked Response (VER), Ocular Ultrasonography, M- Mode ultrasonography, Ocular emergencies
I. INTRODUCTION
M-Mode ultrasonography is a diagnostic tool that evaluates the health of the muscles and the nerves that control them by measuring muscle electrical activity. This test is most commonly performed to determine the cause of muscle weakness and identify cases that are caused by neurologic disorders such as carpal tunnel syndrome, peripheral neuropathy and other primary muscle disorders. (1-9)
During the test, transducer is placed on the skin over the targeted muscle, where it detects electrical activity while the muscle is at rest and when it is contracting. This test is usually performed in conjunction with a nerve conduction velocity test, Electromyography (EMG) and Evoked Response tests.
Normal results of an M -Mode ultrasonography test indicate muscles that do not produce any electrical activity while at rest and progressively increases with contraction. After the test, patients may experience feelings of numbness on the affected muscle.
An evoked response study is a diagnostic procedure that measures electrical activity in the brain as it responds to signals from the sight, sound and touch senses. This allows doctors to assess hearing or sight (especially useful when