Muscle, excitability disorders

Barchi, R.L. (1988). The pathophysiology of excitation in skeletal muscle. In Disorders of Voluntary Muscle (Walton, J.N., ed.), pp. 372-389, Churchill-Livingstone, Edinburgh. 

DISORDERS OF MUSCLE EXCITABILITY 713 MOTOR NEURON DISEASES 731... 

The disorders of muscle excitability are best classified according to their cause [9] and are listed in Table 43-1. 

TABLE 43-1 Disorders of muscle excitability Inheritable diseases... 

Muscle relaxants have some value for relief of spastic muscle disorders, that is, a state of increased muscle tone that results from an imbalance between central and spinal control of muscle tone. Spasticity is the result of a general release from supraspinal control and is characterized by heightened excitability of a- and y-motor systems and the appearance of primitive spinal cord reflexes. Treatment is difficult, since relief often can be achieved only at the price of increased muscle weakness. 

Leis AA, Kofler M, Stokic DS, et al Effect of the inhibitory phenomenon following magnetic stimulation of cortex on brainstem motor neuron excitability and on the cortical control of brainstem reflexes. Muscle Nerve 16 1351-1358, 1993 Lemke MR Effect of carbamazepine on agitation in Alzheimer s inpatients refractory to neuroleptics. J Clin Psychiatry 56 354-357, 1995 Lemus CZ, Robinson DG, Kronig M, et al Behavioral responses to a dopaminergic challenge in obsessive-compulsive disorder. J Anxiety Disord 5 369-373, 1991 Lena C, Changeux JP Allosteric modulations of the nicotinic acetylchohne receptor. Trends Neurosci 16 181-186, 1993... 

Epilepsy is a chronic neurologic disorder characterized by recurrent seizures.33 Seizures are episodes of sudden, transient disturbances in cerebral excitation that occur when a sufficient number of cerebral neurons begin to fire rapidly and in synchronized bursts.42 Depending on the type of seizure, neuronal activity may remain localized in a specific area of the brain, or it may spread to other areas of the brain. In some seizures, neurons in the motor cortex are activated, leading to skeletal muscle contraction via descending neuronal pathways. These involuntary, paroxysmal skeletal muscle contractions seen during certain seizures are referred to as convulsions. However, convulsions are not associated with all types of epilepsy, and other types of seizures are characterized by a wide variety of sensory or behavioral symptoms. 

Third, advances in biochemistry are enabling researchers to tackle some of the most exciting questions in biology and medicine. How does a fertilized egg give rise to cells as different as those in muscle, brain, and liver How do the senses work What are the molecular bases for mental disorders such as Alzheimer disease and schizophrenia How does the immune system distinguish between self and nonself What are the molecular mechanisms of short-term and long-term memory The answers to such questions, which once seemed remote, have been partly uncovered and are likely to be more thoroughly revealed in the near future. 

The German E Commission has approved St. John s wort for internal consumption for psychogenic disturbances, depressive states, sleep disorders, and anxiety and nervous excitement, particularly that associated with menopause. Oily Hypericum preparations are approved for stomach and gastrointestinal complaints, including diarrhea. Oily Hypericum preparations are also approved by the Commission E for external use for the treatment of incised and contused wounds, muscle aches, and first degree burns (96). 

Segal In the temperature-dependent febrile seizures, the seizures tend to occur typically during a rise in temperature. InvitroX have seen a similar effect in solitary neurons in microisland cultures where it is not the absolute temperature but rather the change in temperature that increases the excitability (M. Segal, unpublished results). Could this be the case for some of the muscle disorders ... 

Caffeine intoxication is the only official diagnosis associated with caffeinism in the DSM-IV-TR. Caffeine-induced anxiety may manifest as restlessness, nervousness, excitement, insomnia, diuresis, flushing, gastrointestinal disturbance, muscle twitching, irritability, and jitteriness. If caffeine-induced insomnia requires specific treatment, caffeine-induced sleep disorder (DSM-IV-TR) is an appropriate diagnosis." ... 

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