TREMORS

1. TREMORS

2. Definition It is defined as more or less involuntary and rhythmic oscillatory movement produced by, alternating or irregularly synchronous contractions of ,reciprocally innervated muscles. Its rhythmic quality helps to differ it from other involuntary movements. Involvement of agonist and antagonist muscles distinguish it from clonus.

3. Normal/Physiological Present in all contrating muscle groups,persists in waking state and even through phases of sleep. Fine movements,barely seen with naked eye,only if fingers are outstretched 8-13 Hz-childhood,old age,10 Hz in adulthood. Factors affecting the occurrence of the tremor Spindle input Unfused grouped firing rates of motor neurons. Natural resonating frequencies Inertia of muscles and other structures

4. Abnormal/Pathological Preferentially affects certain muscle groups Distal parts of limbs(fingers and hands) less than proximal Rarely head,tongue,jaw ,vocal cords ,trunk involved Present in waking state Rate-> 4-7Hz,fairly constant in affected parts

5. Distinguishing factors 1. Rhythmicity 2. Frequency 3.Relation to movement and posture 4.Pattern of activity of opposing muscles– synchronous or alternating

10. Postural and Action tremor A tremor - present when the limbs , trunk are actively maintained in certain positions (such as holding the arms outstretched) , may persist throughout active movement. Absent when the limbs are relaxed but becomes evident when the muscles are activated. Characterized by relatively rhythmic bursts of grouped motor neuron discharges that occur not quite synchronously and simultaneously in opposing muscle groups Inequalities in the strength , timing of contraction of opposing muscle groups account for the tremor.

11. Enhanced Physiologic Tremor Exaggeration of normal or physiologic tremor and can be brought out in most normal persons. Same freqeuncy(10 Hz) but more amplitude. Best elicited by holding the arms outstretched with fingers spread apart. Enhancement of physiologic tremor that occurs in metabolic and toxic states is not a function of the central nervous system but is instead a consequence of stimulation of muscular beta-adrenergic receptors by increased levels of circulating catecholamines

12. Enhanced Physiologic Tremor Intense fright and anxiety (hyperadrenergic states) Certain metabolic disturbances (hyperthyroidism, hypercortisolism, hypoglycemia) Pheochromocytoma Intense physical exertion Withdrawal from alcohol and other sedative drugs the toxic effects of several drugs—lithium, nicotinic acid, xanthines (coffee, tea, aminophylline, colas), and corticosteroids.

13.  Alcohol and Sedative Withdrawal Tremor Special type of action tremor closely related to, but more complex than, enhanced physiologic tremor. Withdrawal benzodiazepines, barbiturates Two somewhat different tremors 1) Frequency > 8 Hz , continuous activity in antagonistic muscles, greater amplitude ,responsive to propranolol 2) <8 Hz, discrete bursts of electromyelogram (EMG) activity occurring synchronously in antagonistic muscles Either of these may occur after a relatively short period of intoxication ("morning shakes").

14. Essential (Familial) Tremor Commonest type of tremor, lower frequency (4 to 8 Hz) than physiologic tremor ,is unassociated with other neurologic changes; called "essential. Typical essential tremor very occurs as only neurologic abnormality in several members of a family, in which case it is called familial or hereditary essential tremor. Inheritance is as an autosomal dominant trait with virtually complete penetrance. Action tremor- worsening of tremulousness with activity of the limb, but it is the maintenance of a posture that truly exaggerates these tremors.

15. Late in the second decade, may begin in childhood and then persist. A second peak of increased incidence occurs in adults older than 35 years of age Frequency- 4 to 8 Hz, variable amplitude The identifying feature is its appearance or marked enhancement with attempts to maintain a static limb posture Worsened by emotion, exercise, and fatigue Begins in the arms ,is usually symmetrical, it may appear first in the dominant hand(15%) Limited to upper limbs or a side-to-side or nodding movement of the head; the chin may be added or may (rarely) occur independently. advanced cases of essential tremor, there is involvement of the jaw, lips, tongue, and larynx, the latter imparting a severe quaver to the voice (voice tremor)

16. Head tremor is also postural in nature and disappears when the head is supported. The limb and head tremors tend to be muted when the patient walks. The lower limbs are usually spared or only minimally affected. Electromyographic studies reveal , tremor is generated by more or less rhythmic and almost simultaneous bursts of activity in pairs of agonist and antagonist muscles . Tremors at the lower range of frequency, the activity in agonist and antagonist muscles alternates ("alternate beat tremor"), a feature more characteristic of Parkinson disease.

17. Alternate-beat tremor tends to be of higher amplitude and is more of a handicap, is more resistant to treatment. Essential tremor may increase in severity to a point where the patient's handwriting becomes illegible and he cannot bring a spoon or glass to his lips without spilling its contents All tasks that require manual dexterity become difficult or impossible

18. Essential tremor t/t Inhibited by propranolol (between 80 and 200 mg per day in divided doses or as a sustained-release preparation) Anticonvulsant primidone (Mysoline) has also been effective in controlling essential tremor but many of patients have not tolerated the side effects of drowsiness, nausea, and slight ataxia. Gabapentin, topiramate,amantadine Clonazepam for alternate beat essential tremor Injections of botulinum toxin

19. Tremor of Polyneuropathy Prominent feature of the polyneuropathy caused by immunoglobulin (Ig) M antibodies to myelin-associated glycoprotein (MAG) Simulates coarse essential tremor or ataxic tremor , typically worsens if the patient is asked to hold his finger near a target. EMG pattern is more irregular than that in the essential (familial) tremor Vary in amplitude with side-to-side oscillation, which is induced by cocontracting muscle activity; they also have little suppression of the tremor with loading of the limb.

20. Special type of Guillain-Barré syndrome is characterized by a tremor that is indistinguishable from ataxia Inherited disease peroneal muscular atrophy (Charcot-Marie-Tooth disease) Coarse action tremor, combined with myoclonus, accompanies various types of meningoencephalitis (e.g., in the past it was quite common with syphilitic general paresis) certain intoxications (methyl bromide and bismuth).

21. Parkinsonian/Rest Tremor Coarse, rhythmic tremor , frequency of 3 to 5 Hz. EMG,it is characterized by bursts of activity that alternate between opposing muscle groups. Localized in one or both hands and forearms , less frequently in the feet, jaw, lips, or tongue Limb is in an attitude of repose and is suppressed or diminished by willed movement, at least momentarily, only to reassert itself once the limb assumes a new position If the tremulous hand is completely relaxed, as it is when the arm is fully supported at the wrist and elbow, the tremor usually disappears; however, the patient rarely achieves this state.

22. He maintains a state of slight tonic contraction of the trunk and proximal muscles of the limbs In complete rest, i.e., in all except the lightest phases of sleep, the tremor disappears. Is "alternating" in the sense that it takes the form of flexion–extension or abduction–adduction of the fingers or the hand; pronation–supination of the hand and forearm is also a common presentation. Flexion–extension of the fingers in combination with adduction–abduction of the thumb yields the classic "pill-rolling" tremor of Parkinson disease. It continues while the patient walks, unlike essential tremor; indeed, it may first become apparent or be exaggerated during walking.

23. Legs are affected, the tremor takes the form of a flexion–extension movement of the foot, sometimes the knee; in the jaw and lips, it is seen as up-and-down and pursing movements, respectively. Eyelids, if they are closed lightly, tend to flutter rhythmically (blepharoclonus) The tongue, when protruded, may move in and out of the mouth at about the same tempo as the tremor elsewhere. Cogwheel effect, which is perceived by the examiner on passive movement of the extremities (the Negro sign), is said by many authors to be no more than a palpable tremor superimposed on rigidity and as such is not specific for Parkinson disease although it is most prominent in that condition

24. Frequency is surprisingly constant over long periods, but the amplitude is variable Emotional stress augments the amplitude and may add the effects of an enhanced physiologic or essential tremor. Increasing rigidity of the limbs obscures or reduces The tremor interferes surprisingly little with voluntary movement; for example, it is possible for a tremulous patient to raise a full glass of water to his lips and drain its contents without spilling a drop Resting tremor a manifestation of paralysis agitans or drug-induced type

25. The tremor is sometimes relatively gentle and more or less limited to the distal muscles. It is asymmetrical and at the outset, it may be entirely unilateral .A parkinsonian type of tremor may also be seen in elderly persons without akinesia, rigidity, or mask-like facies Patients with the familial (wilsonian) or acquired form of hepatocerebral degeneration may also show a tremor of parkinsonian type, usually mixed with ataxic tremor and other extrapyramidal motor abnormalities.

26. Treatment Suppressed to some extent by the phenothiazine derivative ethopropazine (Parsidol), trihexyphenidyl (Artane), and other anticholinergic drugs; L-dopa and dopaminergic agonist drugs. Stereotactic lesions or electrical stimulation in the basal ventrolateral nucleus of the thalamus diminishes or abolishes tremor contralaterally Parkinsonian tremor is often associated with an additional tremor of faster frequency; the latter is of essential type , responds better to beta-blocking drugs than to anti-Parkinson medications

27. Intention (Ataxic, Cerebellar) Tremor Intention is ambiguous in this context because the tremor itself is not intentional , occurs not when the patient intends to make a movement but only during the most demanding phases of active performance. Ataxic is a suitable substitute for intention, because this tremor is always combined with cerebellar ataxia and adds to it. It requires for its full expression the performance of an exacting, precise, projected movement. The tremor is absent when the limbs are inactive and during the first part of a voluntary movement, but as the action continues and fine adjustments of the movement are demanded (e.g., in touching the tip of the nose or the examiner's finger) an irregular, more or less rhythmic (2- to 4-Hz) interruption of forward progression with side-to-side oscillation appears and may continue for several beats after the target has been reached.

28. The tremor is absent when the limbs are inactive and during the first part of a voluntary movement, but as the action continues and fine adjustments of the movement are demanded (e.g., in touching the tip of the nose or the examiner's finger) an irregular, more or less rhythmic (2- to 4-Hz) interruption of forward progression with side-to-side oscillation appears and may continue for several beats after the target has been reached. oscillations occur in more than one plane. Tremor and ataxia may seriously interfere with the patient's performance of skilled acts

29. Some patients there is a rhythmic oscillation of the head on the trunk (titubation), or of the trunk itself, at approximately the same rate Type of tremor points to cerebellar disease or its connections, particularly via the superior cerebellar peduncle, but certain peripheral nerve diseases may occasionally simulate it. More violent type of tremor associated with cerebellar ataxia, in which every movement, even lifting the arm slightly or maintaining a static posture with the arms held out to the side, results in a wide-ranging, rhythmic 2- to 5-Hz "wing-beating" movement, sometimes of sufficient force to throw the patient off balance

30. Lesion is usually in the midbrain, involving the upward projections of the dentatorubrothalamic fibers , the medial part of the ventral tegmental reticular nucleus Because of the location of the lesion in the region of the red nucleus, Holmes originally called this a rubral tremor. Experimental evidence in monkeys indicates that the tremor is produced not by a lesion of the red nucleus per se but by interruption of dentatothalamic fibers that traverse this nucleus—i.e., the cerebellar efferent fibers that form the superior cerebellar peduncle and brachium conjunctivum (Carpenter)

31. Patients with multiple sclerosis , Wilson disease, occasionally with vascular and other lesions of the tegmentum of the midbrain and subthalamus, and rarely as an effect of antipsychotic medications. Abolished by a surgical or ischemic lesion in the opposite ventrolateral nucleus of the thalamus. Beta-adrenergic blocking agents, anticholinergic drugs, and L-dopa have little therapeutic effect Thalamic stimulation may be helpful in severe cases

32. Geniospasm strongly familial episodic tremor disorder of the chin and lower lip begins in childhood and may worsen with age Psychic stress and concentration are known to precipitate the movements,described as trembling. Rarely involve facial muscles Trait is inherited in an autosomal dominant fashion from a locus on chromosome 9.

33. Primary Orthostatic Tremor Rare but striking tremor isolated to the legs Its occurrence is only during quiet standing and its cessation almost immediately on walking Difficult to classify ,more relevant to disorders of gait than it is to tremors of other types. Frequency -14 to 16 Hz Produces considerable disability as the patient attempts to stabilize himself in response to the tremulousness. Accompanying feature is the sensation of severe imbalance, which causes the patient to assume a widened stance while standing; these patients are unable to walk a straight line (tandem gait)

34. Prominent tonic contraction of the legs during standing, seemingly in an attempt to overcome imbalance Falls are surprisingly infrequent, the condition is often attributed to hysteria. Arms are affected little or not at all First step or two when the patient begins to walk are halting, but thereafter, the gait is entirely normal Tremulousness is not present when the patient is seated or reclining, but in the latter positions it can be evoked by strong contraction of the leg muscles against resistance.

35. Treatment Administration of clonazepam, gabapentin, primidone, or sodium valproate. Implanted spinal cord stimulator

36. Dystonic Tremor Tremors that are intermixed with dystonia When the underlying dystonic posturing is not overt, the tremor may be ascribed to the essential variety or to hysteria. Focal, superimposed for example on torticollis, or it may be evident in a dystonic hand Movement is not entirely rhythmic, sometimes jerky, and often intermittent

37. Psychogenic Tremor Dramatic manifestation of hysteria Simulates many types of organic tremor, causing difficulty in diagnosis. Usually restricted to a single limb; they are gross in nature, are less regular than the common static or action tremors, and diminish in amplitude or disappear if the patient is distracted. When asked to make a complex movement with the opposite hand. If the examiner restrains the affected hand and arm, the tremor may move to a more proximal part of the limb or to another part of the body ("chasing the tremor").

38. Identifying hysterical tremor are exaggeration of the tremor by loading the limb By having the patient hold a book or other heavy object—which reduces almost all other tremors with exception of those produced by polyneuropathy Persists in repose and during movement .

39. Tremors of Complex type Some parkinsonian patients, for example, the tremor is accentuated rather than dampened by active movement; in others, the tremor may be very mild or absent "at rest" and become obvious only with movement of the limbs. A patient with classic parkinsonian tremor may, in addition, show a fine essential tremor of the outstretched hands and occasionally even an element of ataxic tremor as well. Essential or familial tremor may, in its advanced stages, assume the aspects of a cerebellar tremor.

40. Pathophysiology Rhythmic burst discharges of unitary cellular activity in the nucleus intermedius ventralis of the thalamus (as well as in the medial pallidum and subthalamic nucleus) synchronous with the beat of the tremor. Neurons that exhibit the synchronous bursts are arranged somatotopically and respond to kinesthetic impulses from the muscles and joints involved in the tremor stereotaxic lesion in any of these sites abolishes the tremor.

41. Effectiveness of a thalamic lesion in particular may be a result of interruption of pallidothalamic and dentatothalamic projections, or, more likely, of projections from the ventrolateral thalamus to the premotor cortex, as the impulses responsible for tremor are ultimately mediated by the lateral corticospinal tract.

42. Palatal Tremor Rare disorder consisting of rapid, rhythmic, involuntary movements of the soft palate One is essential palatal tremor , reflects the rhythmic activation of the tensor veli palatini muscles; it has no known pathologic basis. palatal movement imparts a repetitive audible click, which ceases during sleep. The second, more common form is a symptomatic palatal tremor  caused by a diverse group of brainstem lesions that interrupt the central tegmental tract(s); these columns contain descending fibers from midbrain nuclei to the inferior olivary complex Former-26 to 420 cycles per minute Latter-107 to 164 cycles per minute

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