| TNR | tonic neck reflex; true negative rate |
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| TVR | tonic vibratory reflex; total vascular resistance; tricuspid valve replacement |
| tonic contraction | Sustained contraction of a muscle, as employed in the maintenance of posture. (05 Mar 2000) |
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| tonic control | Nerve impulses that maintain a normal tonus or level of activity in muscle or other effector organs. (05 Mar 2000) |
| tonic convulsion | A convulsion in which muscle contraction is sustained. Synonym: tetanic convulsion, tonic seizure. (05 Mar 2000) |
| tonic epilepsy | An attack in which the body is rigid. (05 Mar 2000) |
| tonic pupil | Usually a unilateral abnormality of the eye characterised by slow pupillary constriction to light and in which there is a delayed reaction to changes in accommodation and convergence. The affected pupil is usually larger. (12 Dec 1998) |
| tonic reflex | The occurrence of an appreciable interval after the production of a reflex before relaxation, e.g., the leg remains up for a time after a knee jerk. Synonym: Gordon's symptom. (05 Mar 2000) |
| tonic seizure | Sustained contractures of skeletal muscle as occur during convulsions. Synonym: tonic convulsion. (05 Mar 2000) |
| tonic spasm | A continuous involuntary muscular contraction. (05 Mar 2000) |
| epilepsy, tonic-clonic | Primary generalised epileptic seizures, starting without warning, characterised by loss of consciousness, tonic contraction of muscles, loss of postural control, and production of a cry by the forced expiration of air due to contraction of the respiratory muscles. The individual then falls to the floor and remains rigid for a few seconds, after which a series of rhythmic contractions occur in all four limbs. This clonic phase can last for a variable period, ending only upon muscle relaxation. Upon recovery, there is a gradual return to consciousness, disorientation, amnesia for the seizure, sometimes retrograde amnesia as well, headache, and drowsiness. The individual may not return to baseline functioning for days. (12 Dec 1998) |