A 'yes' head tremor also may accompany midline cerebellar lesions. In human beings, a nodding of the head can occur with lesions of the thalamus and one of the authors has seen this in a dog with a thalamic lesion. The pathogenesis of this disease is not known. This is almost the opposite of an intention tremor, as the tremor can be stopped when the dog is focused on a goal-orientated task such as eating. Also, dogs seem to be able to stop this movement if they desire, are conscious, can walk and can respond to verbal commands. Head tremors are usually more prominent when the dog is less active. Sometimes this is referred to as a head bob. Head tremors may be either in an up down or in a side-to-side plane. These dogs have no other clinical abnormalities and are usually young. This head tremor syndrome appears to occur without definable cause in some breeds such as the Doberman pinschers (especially dogs less than 1 year of age), boxers and bulldogs however, a variety of breeds can be affected. In general, movement disorders may have origins in the cerebrocortical neurons, basal nuclei or peripheral nervous system. The localization of the purported functional neurotransmitter based abnormalities responsible for these disorders may be central or peripheral nervous system. The movements can be triggered by excitement or exercise. The descriptions of these conditions indicate that the most common clinical sign is that of dystonia causing increased muscle tone in one or several limbs, possibly leading to collapse. Muscle cramps have also been described secondary to systemic diseases such as hypoadrenocorticism.ĭyskinesias are movement disorders that occur spontaneously during activity or at rest causing involuntary contractions of groups of muscles in a conscious animal. Examples of diseases associated with cramps which may be dyskinesias include Scotty Cramp, episodic falling of Cavalier King Charles spaniels, 'epileptoid cramping' of border terriers, and extreme generalized muscular stiffness in male Labrador retrievers. The impaired movement can appear as and have been termed muscle 'cramps' which are defined as paroxysmal, prolonged and severe contraction of muscles that may be painful and can be either focal or generalized.
The pathophysiologic mechanisms underlying these movements are poorly understood, but may represent a central neurotransmitter or pathway abnormality, or possibly a local muscular abnormality. Dogs reported with these abnormalities may exhibit abnormal postures such as holding up a limb in an attempt to move or adopting a kyphotic posture of the spine without being able to initiate movement. In a patient with a neuromuscular disorder, observation and gait analysis may detect ventroflexion of neck, shortstrided gait with overflexion of joints (often more evident in the pelvic limbs), a plantigrade and/or palmigrade stance at rest, and generalised decreased muscle tone.ĭyskinesia is defined as impairment of the power of voluntary movements resulting in fragmented or incomplete movements. At the time of examination, they may appear normal or only mildly affected additionally, if weakness is exhibited, it is rarely specifically indicative of nerve, neuromuscular junction or muscle disease. The interpretation of the neurological examination may be challenging in these patients.
Absolute confirmation of the epileptic nature can only be obtained by observing simultaneously the characteristic EEG changes and physical manifestation of the seizures.Īctivity associated weakness is the most typical clinical sign of neuromuscular disease. These disorders will be discussed in terms of the classical presenting signs and how they may be considered differently from epileptic disorders. Obsessive compulsive disorders will also be mentioned based on their stereotypical presentations and similarities to the focal sensory seizures described in veterinary medicine. sleep disorder and narcolepsy/cataplexy as well a new defined group of disorders of involuntary movement that are predominantly breed related. These include neuromuscular disorders leading to collapse (e.g., myasthenia gravis), cardiovascular disease causing syncope, sleep related events such as R.E.M. There are several broad categories of disease or abnormality that should be considered when determining whether a paroxysmal event is a manifestation of a seizure disorder or not. Books & VINcyclopedia of Diseases (Formerly Associate).VINcyclopedia of Diseases (Formerly Associate).
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