What is loss function

what is loss function

Key terms

Myelography — An x-ray process that uses a dye or contrast medium injected into the space around the spine.

Nerve conduction velocity test — A test that measures the time it takes a nerve impulse to travel a specific distance over the nerve after electronic stimulation.

paralysis

[ pah-ral´ĭ-sis ] (pl. paral´yses .)

Loss or impairment of motor function in a part due to a lesion of the neural or muscular mechanism; also, by analogy, impairment of sensory function (sensory paralysis ). Paralysis is a symptom of a wide variety of physical and emotional disorders rather than a disease in itself. Called also palsy .

Types of Paralysis. Paralysis results from damage to parts of the nervous system. The kind of paralysis resulting, and the degree, depend on whether the damage is to the central nervous system or the peripheral nervous system.

pa·ral·y·sis

paralysis

loss of muscle function, due to damage at any level in the pathway for neural activation, or to muscle disease or relaxant drugs. See also spinal injury.

paralysis

; palsy loss of voluntary movement due to muscle injury, neuromuscular pathology, loss of blood supply to subserving motor nerve, or motor nerve dysfunction

paralysis 

Loss of action of a muscle due to injury or disease of that muscle or its nerve supply. See palsy .

abducens paralysis See paralysis of the sixth nerve.

paralysis of convergence A condition characterized by an inability of the eyes to converge while all other monocular eye movements are unaffected. The patient notices diplopia in near vision, which usually occurs suddenly. It is presumably due to some lesion in the nuclei responsible for convergence, as may happen in tabes dorsalis or Parkinson's disease.

divergence paralysis A condition characterized by an inability of the eyes to diverge while all other monocular eye movements are unaffected. It is characterized by a sudden development of diplopia with marked esotropia at distance and sometimes headaches. The key difference with divergence insufficiency is the sudden onset of symptoms. Its association includes encephalitis, multiple sclerosis, head trauma, cerebral haemorrhage, brain tumour and vascular lesions of the brainstem.

paralysis of the fourth nerve A condition characterized by a hypertropia

of the eye with the affected superior oblique muscle. It may be due to a lesion of the fourth cranial nerve or its nucleus as a result of injury (the most common cause), vascular lesions, aneurysm or tumour. The patient usually presents with an abnormal head posture to avoid diplopia. If the condition does not recover by itself following therapy of the underlying cause, surgery is usually the only alternative treatment. Syn. trochlear paralysis. See abnormal head posture ; trochlear nerve ; paralytic strabismus.

oculomotor paralysis See paralysis of the third nerve.

paralysis of the sixth nerve A condition characterized by an esotropia of the eye with the affected lateral rectus muscle. It may be due to a lesion of the sixth cranial nerve or its nucleus as a result of a vascular disease (e.g. diabetes, hypertension), injury, or tumour. The patient presents with an abnormal head turn to avoid diplopia. If the condition does not recover by itself following therapy of the underlying cause, surgery is usually the only alternative treatment. Syn. abducens paralysis; lateral rectus palsy. See abnormal head posture ; abducens nerve ; paralytic strabismus; Gradenigo's syndrome ; transposition .

paralysis of the third nerve A condition that leads to a wide impairment of motor function, as this nerve innervates most of the muscles of the eye. It may be due to a vascular disease (e.g. diabetes, hypertension), aneurysm (especially of the internal carotid artery), injury or tumour. In total paralysis only the lateral rectus and the superior oblique muscles will be spared and the eye will be in a position of abduction, slight depression and intorsion. Ptosis will also be present and the pupil will be dilated and non-reactive, and there will also be paralysis of accommodation. If the condition does not recover by itself following therapy of the underlying cause, surgery is usually the only alternative. Syn. oculomotor paralysis. See circle of Willis ; oculomotor nerve ; ophthalmoplegia ; paralytic strabismus; Benedikt's syndrome; Weber's syndrome ; forced duction test; transposition .

trochlear paralysis See paralysis of the fourth nerve.

pa·ral·y·sis

pl. paralyses ( păr-al'i-sis, -sēz )

1. Loss of power of voluntary movement in a muscle through injury or disease of it or its nerve supply.

Source: medical-dictionary.thefreedictionary.com

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