Journial of Neurology, Neurosurgery, and Psychiatry, 1972, 35, 365-372 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.35.3.365 on 1 June 1972. Downloaded from Clinical manifestations of essential tremor EDMUND CRITCHLEY From the Royal Infirmary, Preston SUMMARY A clinical study of 42 patients with essential tremor is presented. In the case of 12 patients the family history strongly suggested an autosomal dominant mode of transmission, in four the mode of inheritance was indeterminate, and the remaining 26 patients were sporadic cases without an established genetic basis. The tremor involved the upper extremities in 41 patients, the head in 25, lower limbs in 15, and trunk in two. Seven patients showed involvement of speech. Variations were found in the speed and regularity of the tremor. Leg involvement took a variety of forms: (1) direct involvement by tremor; (2) a painful limp associated with forearm tremor; (3) associated dyskinetic movements; (4) ataxia; (5) foot clubbing; and (6) evidence of peroneal muscular atrophy. Several minor symptoms hyperhidrosis, cramps, dyskinetic movements, and ataxia-were associated with essential tremor. Other features were linked phenotypically to the ataxias and system degenerations. Apart from minor alterations in tone, expression, and arm swing, features of Parkinsonism were notably absent. Protected by copyright. Essential tremor has been recognized as an or- much variation. It is occasionally present at rest ganic peculiarity of the nervous system, mimick- and inhibited by action, but is more usually de- ing neurotic and neural disorders with equal creased or absent at rest and present on volun- facility. Many synonyms-for example, benign, tary increase in muscle tonus, as in holding a limb hereditary, and senile tremor-describe its varied in a definite position (static, sustained-postural presentation. Dana (1887) regarded 'hereditary' or attitude tremor) and in active movement tremor as a hitherto undescribed form of motor (kinetic or intention tremor). It may be accentu- neurosis, and observed that it resembles to some ated on approaching a goal in point-to-point extent the tremor of paralysis agitans, still more movement (terminal tremor) (Davis and Kunkle, a simple neurasthenic tremor, and was not ac- 1951). In its mildest form the tremor diathesis companied by paralysis or any other disturbance may be no more than a kind of exaggeration of of nervous function. Others commented on its physiological tremor (Kreiss, 1912) properly resemblance to hysteria (Antony and Rouvillois, managed by explanation and reassurance (Davis 1899) and to multiple sclerosis (Bergamesco, and Kunkle, 1951), or it may be so severe as to http://jnnp.bmj.com/ 1907; Dromard, 1908), but many disorders- require stereotactic thalamotomy (Bertrand, notably, anxiety neuroses, inebriety, drug- Hardy, Molina-Negro, and Martinez, 1969). induced tremors, diabetic tremors, chorea, and With the discovery of biogenic transmitter path- thyrotoxicosis may be simulated by essential ways for pathological tremors the need for a tremor. fuller review of the clinical manifestations of Parkinson (1817) and Charcot (1876) dis- essential tremor has become more interesting and tinguished between the tremors of paralysis agi- more urgent. on September 30, 2021 by guest. tans and the senile variant of essential tremor. Both types of tremor characteristically affect the PRESENT STUDY upper limbs. The Parkinsonian tremor involves alternating activation of opposing groups of The present study is based upon a personal series of the axis of the is at 42 patients in North Lancashire. Originally a group muscles along limb, present of 16 patients was selected with sufficient disability rest and disappears with activity. That ofessential to justify a crossover trial of amantadine hydro- tremor, regardless of age of onset, is seen pre- chloride in the treatment of tremor (Cox, Critchley, dominantly in the distal parts of the upper limb Schnieden, and Williams, 1971). This study was (Poirier, 1970), is more or less rhythmical, either carried out in parallel with a clinical assessment of fine or coarse, with a rate of 4 to 12 Hz. There is tremor in a group of Parkinsonism patients receiving 365 366 Edmund Critchley J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.35.3.365 on 1 June 1972. Downloaded from Levodopa. Both groups were repeatedly examined TABLE 2 and monitored by a battery of standardized per- CLINICAL SIGNS formance tests and by serial tremor recordings using a Grass Parkinsonism transducer. The remaining 26 Family history Group I Group I1 Group III Total patients include three originally excluded from the Signs (parent +) (others) (lone) nos. therapeutic trial because their symptoms were so No associated 2 1 13 16 mild that therapy was considered unnecessary. Associated 2 0 4 6 from the Minimal Where possible, other affected members Parkinsonism 5 1 8 14 families of these unrelated propositi were examined Associated and and the findings used to substantiate the manifesta- Parkinsonism 3 2 1 6 tions of the propositus; but owing to the diversity of background and origin of the patients-two were Totals 12 4 26 42 Pakistani, two Jewish, two Irish, and one of Polish extraction-no attempt was made to examine all family members. There were 30 males and 12 females with an age- with maintenance of the typical Parkinsonism range from 16 to 72 years (average 49 years). These posture, with the arms extended and with finger- propositi were divided into three genetic groups: nose movement. Particular attention was also given to the presence of associated neuropathic GROUP I. FAMILIES WITH SECONDARY CASES AND ONE traits. The findings were then classified to assess PARENT AFFECTED 12 cases; four of these involved three generations. The parents of one proband were the presence of minimal signs of Parkinsonism first cousins and her father, two children, sister, and and of associated traits (Table 2). sister's daughter were affected. CHARACTERISTICS OF TREMOR Marshall (1962)Protected by copyright. GROUP II. FAMILIES WITH NO AFFECTED PARENT BUT established two different patterns of upper limb SIBLINGS, PARENT'S SIBLINGS OR GRANDPARENTS tremor for essential tremor. The majority of AFFECTED Four cases: (1) half-sister with Parkin- patients had tremors which described a smooth, sonism; (2) uncle with Parkinsonism; (3) sibling wave form, indistinguishable from that with essential tremor; and (4) grandmother with regular Parkinsonism. seen in Parkinsonism. The frequency of tremor followed the age pattern for physiological tremor GROUP III. SOLITARY CASES 26 cases; including one when the duration was held constant. The other adopted child. With two patients there was evidence patients showed small irregularities in the pat- of other genetically determined traits-namely, tern and Bertrand et al. (1969a) demonstrated premature whitening of hair and clubbed feet. with photokinetic and electromyographic tech- Combining these three groups, the mean age of niques that these incoordinated movements onset of symptoms was 35 years (Table 1). lacked many of the characteristics of tremor. The present series contains many examples of CLINICAL FINDINGS and the tremor forms both the smooth irregular http://jnnp.bmj.com/ but within each of these groups there are broad The clinical examination resembled that used for distal in- the examination of Parkinsonism patients. Tone variations. Those with predominantly movement of the neck volvement, with striking digital tremor, were was examined by passive usually the more irregular, often with a terminal and by passive movement about the wrists and When a elbows simultaneously, with and without re- increment or a sustained-postural flap. from movement of the gross and seemingly isolated irregular movement inforcement synkinetic was made it took the form of a speedily executed observed at rest, on September 30, 2021 by guest. opposite arm. The tremor was rapid but faulty adjustment. In one individual it was possible to observe continuous sideways jerking of the right forearm and a rhythmic TABLE 1 movement of the left forearm. Involvement of AGE OF ONSET OF SYMPTOMS the whole limb was most common in those with a smoother more regular tremor of the Parkin- Onset ofsymptoms (by decade) sonism type. The speed of tremor was indepen- 0-9 10-19 20-29 20-39 40-49 50-59 60 + (no.) (no.) (no.) (no.) (no.) (no.) (no.) dent of the wave form and both smooth and were in some instances fast 7 7 7 8 5 6 irregular tremors 2 (between 8 to 10 Hz) and in others slow (though Clinical manifestations of essential tremor 367 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.35.3.365 on 1 June 1972. Downloaded from not usually below 5 Hz). Fast tremors were more others did not. The men usually found spirits common than slow tremors in the ratio 3:2. most helpful but it was not uncommon for a lady Much variation was observed in the response to say that two pints of beer or a glass of stout to cold, nervousness, stress, fatigue, and emotion. helped best of all. A fine task might result in an exaggeration of the Handwriting was often affected by the tremor tremor or, contrariwise, there might be an and influenced by emotional factors. One amplification of disability when lifting or carry- patient showed micrographia, but typically the ing heavy objects. The tremor often varied writing was large, untidy, and indecipherable. according to the time of day thus, I.B. found Some patients were able to write neatly provided her tremor most incapacitating in the morning, they pressed harder so as to limit the size of the not immediately on rising but when she came to script and prevent sudden, jerky movements of wash and dress, and E.F. had no trouble during the pen. Commonly they would avoid writing in the day but stopped evening visits to his office to public, putting things aside for signature until prepare ahead as fatigue made him dithery and feeling particularly well.