Disorders of motor function

Disorders of motor function include disorders of the skeletal muscle, the neuromuscular junction, and the peripheral nerves.

  Muscular dystrophy is a number of disorders that produce progressive degradation of skeletal muscle. Muscle necrosis is followed by fat and connective tissue replacement. Duchenne muscular dystrophy, is inherited as a X-linked trait and transmitted by the mother to her male offspring.

Myasthenia gravis is a disorder of the neuromuscular junction resulting from a deficiency of functional acetylcholine receptors, which causes weakness of the skeletal muscles. Because the disease affects the neuromuscular junction, there is no loss of sensory function. The most common manifestations are weakness of the eye muscles, with ptosis and diplopia; the jaw muscles, which make chewing and swallowing difficult; and proximal muscles and extremities, which make climbing stairs and lifting objects difficult.

Disorders of peripheral nerves

 include mononeuropathies and polyneuropathies.

 Mononeuropathies involve a single spinal nerve, plexus, or peripheral nerve trunk. Carpal tunnel syndrome, a mononeuropathy, is caused by compression of the medial nerve that passes through the carpal tunnel in the wrist.

Polyneuropathies involve multiple peripheral nerves and produce symmetric sensory, motor, and mixed sensorimotor deficits.

 Guillain-Barre syndrome is a subacute polyneuropathy of uncertain origin. It causes progressive ascending motor, sensory, and ANS manifestations. Respiratory involvement may occur and necessitate mechanical ventilation.

Alterations in coordination of muscle movements

Alterations in coordination of muscle movements and abnormal muscle movements result from disorders of the basal ganglia and cerebellum. The basal ganglia organize basic movement patterns into more complex patterns and release them when commanded by the motor cortex, contributing gracefulness to cortically initiated and controlled skilled movements. Disorders of the basal ganglia are characterized by involuntary movements, alterations in muscle tone, and disturbances in posture. These disorders include tremor, tics, chorea, athetosis, dystonias, and dyskinesias.

Parkinsonism, a disorder of the basal ganglia, is characterized by destruction of the nigrostriatal pathway, with a subsequent reduction in striatal concentrations of dopamine.

This results in an imbalance between the inhibitory effects of dopaminergic basal ganglia functions and an increase in the excitatory cholinergic functions. The disorder is manifested by of slowness of movement (i.e., bradykinesia), increased muscle tonus and rigidity, rest tremor, gait disturbances, and impaired autonomic postural responses.

The cerebellum is responsible for smoothing of rapid movement in the body. The cerebellum also to have a role in learning both motor and cognitive tasks in which skilled responses are developed through repeated practice. Cerebellar disorders include vestibulocerebellar dysfunction, cerebellar ataxia, and cerebellar tremor.

Spinal cord injury

Spinal cord injury is a neurologic condition most commonly caused by motor vehicle accidents, falls, and sports injuries. Dysfunctions of the nervous system after SCI comprise various degrees of sensorimotor loss and altered reflex activity. Depending on the level of injury, the physical problems of SCI include spinal shock; ventilation and communication problems; next, autonomic nervous system dysfunction, that predisposes to the vasovagal response, autonomic hyperreflexia, impaired body temperature regulation, and postural hypotension; impaired muscle pump and venous innervation leading to edema of dependent areas of the body and risk of deep vein thrombosis; altered sensorimotor integrity that contributes to uncontrolled muscle spasms, altered pain responses, and threat to skin integrity; alterations in bowel and bladder elimination; and impaired sexual function.

 

Demyelinating Diseases

Demyelinating diseases are an important group of neurological disorders which have the pathologic features of focal or patchy destruction of myelin sheaths in the CNS and peripheral nervous system. The true cause of demyelination is not known. There are suggestions the demyelination may be caused by some viral infection or by autoimmune processes.

Multiple or disseminated sclerosis is the most widespread demyelinating disease of CNS. The first symptoms, as a rule, appear at age of 20 to 40 years. The disease is characterized by recurrent attacks with focal neurologic disorders and with lesions of the spinal cord, optic nerve and brain.