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The three main signs of hyperekplexia are generalized stiffness, excessive startle response beginning at birth, and nocturnal myoclonus. [5] Affected individuals are fully conscious during episodes of stiffness, which consist of forced closure of the eyes and an extension of the extremities followed by a period of generalised stiffness and uncontrolled falling at times. [6]
The startle reflex is a brainstem reflectory reaction (reflex) that serves to protect vulnerable parts, such as the back of the neck (whole-body startle) and the eyes (eyeblink) and facilitates escape from sudden stimuli. It is found across many different species, throughout all stages of life.
People suffering from hypervigilance may become preoccupied with scanning their environment for possible threats. They might overreact to loud and unexpected noises, exhibit an overactive startle response or become agitated in highly crowded or noisy environments. They will often have a difficult time getting to sleep or staying asleep. [7]
Knee jerk or patellar reflex — a kick caused by striking the patellar tendon with a tendon hammer just below the patella, stimulating the L4 and L3 reflex arcs. Moro reflex , a primitive reflex — only in all infants up to 4 or 5 months of age: a sudden symmetric spreading of the arms, then unspreading and crying, caused by an unexpected ...
Prepulse inhibition: preceding stimulus attenuates the startle response.. Prepulse inhibition (PPI) is a neurological phenomenon in which a weaker prestimulus (prepulse) inhibits the reaction of an organism to a subsequent strong reflex-eliciting stimulus (pulse), often using the startle reflex.
Fear-potentiated startle (FPS) is a reflexive physiological reaction to a presented stimulus, and is an indicator of the fear reaction in an organism. The FPS response can be elicited in the face of any threatening stimulus (e.g., any object, person or situation that would cause someone to experience feelings of fear), but it can also be elicited by a neutral stimulus as a result of fear ...
Symptoms associated with central nervous systems disorders are classified into positive and negative categories. Positive symptoms include those that increase muscle activity through hyper-excitability of the stretch reflex (i.e., rigidity and spasticity) where negative symptoms include those of insufficient muscle activity (i.e. weakness) and reduced motor function. [5]
In many people with hyperacusis, an increased activity develops in the tensor tympani muscle in the middle ear as part of the startle response to some sounds. This lowered reflex threshold for tensor tympani contraction is activated by the perception/anticipation of loud sound, and is called tonic tensor tympani syndrome (TTTS). In some people ...