Unilateral motor epileptic seizures

Unilateral motor epileptic seizures

Unilateral motor epileptic seizures M. J. Eadie MD Department of Medicine, University of Queensland. Unilateral m o t o r epileptic seizures occurr...

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Unilateral motor epileptic seizures M. J. Eadie

MD

Department of Medicine, University of Queensland.

Unilateral m o t o r epileptic seizures occurred in 118 o f 1902 persons with seizure disorders referred to a consultant neurological practice over a 30 year period. The unilateral m o t o r seizures were nearly always manifestations o f partial (focal, localisation related) epilepsy but, particularly if they occurred on different sides o n different occasions, could be due to generalised onset epilepsy (10.2% o f cases). T h e risk o f cerebral tumour in those with unilateral m o t o r seizures (10.2%) was greater than that for those with all other f o r m s o f seizure disorder (relative risk 3.56 times; 95% C.I. = 1.95 to 6.49 times). Unlike the situation in younger persons, if unilateral m o t o r seizures began after the age o f 20 years the chance o f an underlying cerebral turnout (23.4%) was significantly higher than in other persons with adult onset partial seizures (relative risk 2.62 times; 95% C.I. = 1.44 to 4.77 times) and was m u c h greater than that in all other seizure sufferers (relative risk 8.35 times; 95% C.I. = 4.66 to 14.9 times).

© Longman Group UK Ltd

Journal of Clinical Neuroscience 1995, 2 (1) :36-39

Keywords: Tumour, Partial seizure, Focal epilepsy, Unilateral seizure

Introduction At the present time a patient's type of epileptic seizure or seizures is usually categorised on the basis of the ILAE Classification of Epileptic Seizures, 1 and the epileptic syndrome that is present is then determined. The initial categorisation of seizure type is fairly heavily d e p e n d e n t on EEG evidence. However, even before this evidence is available, at the time of the initial clinical contact, the description of the features of the patient's seizure or seizures may p e r m i t provisional interpretation of the seizure type and its implications. One of the more distinctive ways in which epileptic seizures may present is as episodes which begin with involuntary motor activity involving part or all of one side of the body, w h e t h e r or not this activity subsequently becomes bilateral a n d / o r consciousness is impaired. The following p a p e r analyses a series of 118 patients who presented with such unilateral m o t o r epileptic seizures. The study attempts to determine if, and in what ways, these persons differed from persons with o t h e r patterns o f epileptic seizure.

Materials and methods Over the period 1961-1991, all patients with at least one epileptic event who were referred to the writer's consultant neurological practice had their relevant clinical data entered on a standardised p r o f o r m a and subsequently i n c o r p o r a t e d in a database r u n n i n g u n d e r the microc o m p u t e r p r o g r a m DBASE III. Data from subsequent consultations were also entered on to the database. The University o f Q u e e n s l a n d H u m a n R e s e a r c h Ethics Committee approved the analysis of the accumulated data.

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At the time of analysis, the database included details of 1902 patients. These subjects included 118 persons who had presented with one-sided m o t o r epileptic seizures described by themselves a n d / o r by eyewitnesses. These 118 persons comprised the patient group studied, while the remaining 1784 members of the full series, or for some purposes a defined subset of them, provided a comparator group. As far as possible, all subjects had routine surface l e a d EEGs r e c o r d e d at, or s o o n after, the initial consultation, with subsequent EEGs being r e c o r d e d as i n d i c a t e d clinically. Advice was given c o n c e r n i n g t r e a t m e n t , b u t m a n a g e m e n t a n d any d e c i s i o n f o r subsequent referral always remained in the hands of the treating practitioner, in accord with the conventions of Australian consultant neurological practice. These latter circumstances were likely to have influenced the subject follow-up rates and the outcomes of therapy.

Results The 118 patients with unilateral motor seizures comprised 47 m a l e s a n d 71 f e m a l e s , a 6 0 . 2 % : 3 9 . 8 % f e m a l e p r e p o n d e r a n c e that was almost statistically significantly greater than in the comparator 1784 subjects (females 51.5%; difference 8.66%: 95% C.I. = -0.48% to 17.8%). At presentation, the subjects with unilateral m o t o r seizures had a mean age of 25.67 + SD 20.90 years (range 0 to 73 years) while the comparator group had a mean age of 25.96 + SD 17.98 years (range 0 to 85 years: difference = 0.29 years: 95% C.I. = -3.10 to 3.68 years). The seizure disorder onset ages were n o t statistically significantly different in the two groups (21.75 + SD 21.21 years--range

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Unilateral motor epilepsy

Clinical studies

0 to 69 years versus 19.64 + SD 17.45 y e a r s - - r a n g e 0 to 80 years: difference = 2.11 years; 95% C.I. = -1.19 to 5.41 years). However, at presentation the seizure disorder was of shorter m e a n duration in the unilateral m o t o r seizure g r o u p (3.92 + SD 6.60 y e a r s - - r a n g e 0 to 36 years) than in the c o m p a r a t o r g r o u p (6.34 + SD 8.95 y e a r s - - r a n g e 0 to 63 years: difference = 2.42 years; 95% C.I. = 0.78 to 4.06 years). Sixteen of the 118 subjects with u n i l a t e r a l m o t o r seizures were r e f e r r e d after their first known epileptic event, as were 249 of the 1784 c o m p a r a t o r subjects (13.6% versus 14.0%: difference = 0.4%: 95% C.I. = -5.99% to 6.78%). T h e unilateral m o t o r seizures were at times associated with generalised tonic-clonic seizures in 42 subjects (35.6%), while such bilateral convulsive seizures occurred at times in 1170 of the 1784 c o m p a r a t o r subjects (65.6%), the difference (30.6%) having a 95% C.I. of 21.1% to 38.9%. In 7 of the 118 subjects the unilateral m o t o r seizures o c c u r r e d on different sides of the body on different occasions. It m i g h t have b e e n e x p e c t e d that u n i l a t e r a l m o t o r seizures w o u l d n e a r l y always b e a m a n i f e s t a t i o n o f p a r t i a l o n s e t (localisation r e l a t e d ) epilepsy. However, the EEG evidence suggested that 12 of the 118 subjects (10.2%) h a d generalised onset epilepsy; this was a lower incidence of generalised onset epilepsy than in the c o m p a r a t o r group (34.8%: difference = 24.6%; 95% C.I. = 18.8% to 30.5%): conversely, the incidence of partial epilepsy was higher in the unilateral m o t o r seizure g r o u p (89.8% versus 51.7%). T h e 12 subjects with unilateral m o t o r seizures a n d generalised onset epilepsy Table 1

i n c l u d e d 6 o f the 7 p e r s o n s m e n t i o n e d above whose seizures o c c u r r e d on different sides in different attacks. At t i m e o f p r e s e n t a t i o n , the m e a n seizure d i s o r d e r duration was 5.38 + SD 5.11 years in those with generalised onset epilepsy and unilateral m o t o r seizures whose side of o c c u r r e n c e varied, but 0.97 + SD 0.82 years in those whose seizures r e m a i n e d consistently on the same side (difference = 4.41 years: 95% C.I. = -0.29 to 9.12 years). T h e outcomes of a n u m b e r of comparisons between the 118 unilateral m o t o r seizure patients and the 1784 remaining seizure disorder sufferers are set out in Table 1. Brain tumours, a b n o r m a l findings on neurological e x a m i n a t i o n , a n d focal a b n o r m a l i t i e s in the r o u t i n e surface lead EEG were m o r e f r e q u e n t in the unilateral m o t o r seizure subjects, whereas past histories of infantile convulsions and family histories of seizure disorders were less frequent. T h e prospects of o b t a i n i n g full seizure control for at least one year were less, t h o u g h reasonably similar percentages of b o t h groups ultimately went long e n o u g h (3 to 5 years) with full seizure control to warrant a trial withdrawal of anticonvulsant therapy. Many of the differences between the two groups s e e m e d likely to be due to the p r e d o m i n a n c e of partial seizure sufferers in the unilateral m o t o r seizure group, partial seizures being well k n o w n to have an a s s o c i a t i o n with local b r a i n pathology. However, this association raised the question of whether the differences in the p r o p o r t i o n s of partial seizure sufferers in the two groups explained the higher incidence o f cerebral t u m o u r in the unilateral m o t o r seizure sufferers.

Comparison of a number of features in the unilateral m o t o r seizure group and the remaining patients with seizures

Feature

Unilateral motor seizures N=118

Comparator group N=1784

History of: • birth difficulty • prematurity • head injury • brain tumour • infantile convulsions

1.69 5.08 8.47 10.2 3.39

1.85 4.48 6.00 2.86 10.6

0.16 0.60 2.48 7.31 7.2

Family history of seizure disorders: • total • 1st° relatives • 2nd ° relatives • more distant relatives • infantile convulsions Abnormal neurological findings

20.3 9.32 2.54 5.08 3.39 37.3

31.0 12.4 7.74 6.61 4.26 14.9

10.7 3.07 5.19 1.53 0.87 22.4

3.09to 18.2 -2,40 to 8.53 2.09 to 8.29 -2.60 to 5.56 -2.53 to 4.27 13.5 to 31.3

1692 cases 31.4 6.74 19.1 10.4 26.4

13.0 2.85 15.8 0.28 5.68

5.19 to -1.06 to 6.41 to -5.86 to -3.57 to

10.8 15.2 9.73 1.81 0.11

3.20 to 18.3 4.77 to 25.6 0.48 to 19.0 -4.42 to 8.03 -0.53 to 0.75

EEG appearance in-• diagnostic • paroxysmal • focally abnormal • non-specific • normal Seizure control • full (% of all cases) • full (% of known outcomes) • incomplete (% of known outcomes) • ceased therapy Mean (+_ SD) times seen Note:

103 cases 18.4 3.88 35.0 10.7 32.0

20.3 30.0 47.5 12.7 2.91 (3,70)

Difference

31.1 45.2 37.7 14.5 3.02 (3.40)

9 5 % C.I.

-2.26 to -3.48 to -2.67 to 1.80 to 3.64 to

2.57 4.68 7.62 12.8 10.8

20.0 6.77 25.2 6.42 14.9

All valuesare percentagesexceptfor the mean numbers of times seen.

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Unilateral motor epilepsy

Cerebral tumou r and unilateral motor seizures T h e incidence of cerebral tumours was c o m p a r e d in the unilateral m o t o r seizure sufferers with partial epilepsy (a subset which c o n t a i n e d all the instances o f c e r e b r a l t u m o u r in the unilateral m o t o r seizure group) a n d in all o t h e r persons with partial seizures f r o m the whole series. T h e t u m o u r incidences were 12 in 103 subjects and 49 in 922 subjects respectively (11.7% versus 5.31%: difference = 6.34%; 95% C.I. = -0.027% to 12.7%). T h e relative risk of t u m o u r in those with unilateral m o t o r seizures due to partial epilepsy was 2.19 times that for all other persons with partial epilepsy (95% C.I. = 1.21 to 3.98 times) and 3.56 times that for all other persons with seizures, whatever the seizure type (95% C.I. = 1.95 to 6.49 times). T h e t u m o u r s in the unilateral m o t o r seizure g r o u p were gliomas in 7 subjects, a m e n i n g i o m a in one, and metastases in 4. Nine of the 12 t u m o u r sufferers had a degree of hemiparesis (one plus hemianopia) at presentation, and a f u r t h e r subject b e c a m e h e m i p a r e t i c later, o n e was dysphasic and o n e h a d no clinically detectable neurological deficit at any stage till transferred for neurosurgical care. T h e t u m o u r sufferers were older than the r e m a i n d e r of the unilateral m o t o r seizure g r o u p when their seizures b e g a n (mean age 45 versus 19 years) a n d they presented sooner after their first attack (mean 1.30 versus 4.21 years). T h e r e l a t i o n s h i p b e t w e e n age of o n s e t of seizure disorder and risk of t u m o u r was examined. Considering only those whose attacks had c o m m e n c e d at or before the age of 20 years, the t u m o u r risk was 1.41% in unilateral m o t o r seizure sufferers, and 2.21% in all others with partial seizures (risk ratio = 0.64; 95% C.I. = 0.0834 to 4.85). In contrast, considering only seizures which began after 20 years of age, the t u m o u r risks in the unilateral m o t o r seizure sufferers and in all others with partial seizures were 23.4% and 8.94% respectively. T h e relative risk was 2.62 times greater in the f o r m e r g r o u p (95% C.I. = 1.44 to 4.77 times). If the risks were c o m p a r e d for all persons with unilateral m o t o r seizures beginning after 20 years of age and for all other persons f r o m the original series of 1902 patients, the relative risk of t u m o u r was 8.35 times greater (95% C.I. = 4.68 to 14.6 times) in the f o r m e r group. In the unilateral m o t o r seizure sufferers the t u m o u r risk, by decade, was: 0 to 10 years, 1.92%: 11 to 20 years, 0%: 21 to 30 years, 25%: 31 to 40 years, 0%: 41 to 50 years, 28.6%: 51 to 60 years, 33.3%: over 60 years, 30%.

Discussion At a time when the ILAE Classification of epileptic seizures has come into widespread, if not universal, use it may seem r a t h e r anachronistic to analyse a set of patients with epileptic seizures which have b e e n categorised on what are essentially old fashioned clinical p h e n o m e n o l o g i c a l grounds. Yet the g r o u p so defined is one that is easily recognised clinically and its analysis has yielded some useful insights. O n first principles it m i g h t have b e e n expected that unilateral m o t o r seizures would almost always prove to be manifestations of partial (localisation related or focal)

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epilepsy. However in practice this was not invariably the case, though it proved to be so in the great majority of instances. In a minority of the unilateral m o t o r seizure sufferers the underlying seizure disorder a p p e a r e d to be a generalised onset epilepsy rather than the anticipated partial epilepsy. In this small subgroup with generalised o n s e t epilepsy, u n i l a t e r a l m o t o r seizures s o m e t i m e s o c c u r r e d o n d i f f e r e n t sides on d i f f e r e n t occasions. Further, those with unilateral m o t o r seizures d u e to generalised onset epilepsy whose seizures always occurred on the same side had seizure disorder durations when they p r e s e n t e d which were almost statistically significantly shorter than those whose seizures occurred on different sides. Possibly over a longer period of observation, some of the first s u b g r o u p may have also showed c h a n g i n g lateralisations o f their seizures. T h e p h e n o m e n o n o f unilateral m o t o r seizures occurring as a manifestation of generalised epilepsy has b e e n recognised previously. 2 M a n y o f the d i f f e r e n c e s b e t w e e n t h e g r o u p o f unilateral m o t o r seizure sufferers a n d the c o m p a r a t o r g r o u p s e e m e d explicable on the basis of the excess of partial seizure sufferers in the f o r m e r group (89.8% versus 51.7%). T h e differences b e t w e e n the partial a n d the generalised onset seizure sufferers in the whole seizure disorder population which forms the basis of the present p a p e r have b e e n described elsewhere, s T h e excess of partial seizure sufferers in the unilateral m o t o r seizure g r o u p correlated with the known higher incidence of cerebral tumours in this group. 4'5 If unilateral m o t o r seizures affected different sides in different attacks, or if there was EEG evidence of generalised onset epilepsy in a patient with unilateral m o t o r seizures, there a p p e a r e d to be little risk of an underlying cerebral tumour. O n the o t h e r h a n d , if unilateral m o t o r seizures consistently affected the same side and b e g a n after the age of 20 years there was a considerably increased risk of an underlying cerebral turnout. This risk was appreciably greater (8.35 times) than that for all other persons with seizures and also than that for all o t h e r patients with partial onset seizures which b e g a n in adult life (2.62 times). Because the case series was drawn f r o m a specialist consultant practice the possibility arises of bias due to selective referral o f patients, inflating the t u m o u r i n c i d e n c e figures. However, in the p r e s e n t series in m o r e r e c e n t years practitioners o f first contact h a d increasing access to c o m p u t e d t o m o g r a p h y services. This should have led to m o r e t u m o u r cases being recognised and referred direct to neurosurgeons. Therefore the m m o u r incidence figures may be, if anything, underestimates of the true situation in the general community. An association between focal seizures ( p r e s u m a b l y c o n t r a l a t e r a l m o t o r ones) a n d ' m o r b i d growths' n e a r the m o t o r cortex was known to Gowers in 1893. 6 However, his c o n c e p t of focal epilepsy was m o r e restricted than the present day one, since he did n o t recognise that an a u r a to an epileptic seizure necessarily indicated that the seizure in question was a partial (focal) one. Subsequent authors have often not r e m a r k e d on any particular association between focal m o t o r seizures a n d c e r e b r a l t u m o u r s , (e.g. 7) t h o u g h Mathieson s stated that tumour proximity to the m o t o r strip

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Clinical studies

or the frontal lobe increased the c h a n c e of epileptic seizures occurring. N o n e of these authors quantified the degree of increased risk. T h e risk of an underlying cerebral t u m o u r makes adult onset unilateral m o t o r seizures a particularly hazardous variety of epileptic p h e n o m e n o n . It is one which can be identified with reasonable probability on the basis of the clinical history alone. Its recognition probably provides sufficient grounds for carrying out nenroimaging immediately, and for being p r e p a r e d to consider repeating the p r o c e d u r e later if the initial investigation proves negative. Received9 August 1994 Accepted for publication 1 September 1994

Correspondence and offprint requests: Professor MJ. Eadie, Department of Medicine, The University,of Queensland, Royal Brisbane Hospital, Brisbane 4029, Australia. Tel: 61 7 365 5729 Fax: 61 7 365 5581

References 1. Commission on Classification and Terminology of the International League Against Epilepsy. Proposal for classification of epilepsies and epileptic syndromes. Epilepsia 1985;26:268-78. 2. Gastaut H, Broughton R, Tassinari CA, RogerJ. Unilateral epileptic seizures. In: Vinken PJ, Bruyn GW (eds) Handbook of Clinical Neurology 1974;15:235-45. 3. Eadie MJ. Epileptic seizures in 1902 patients: a perspective from a consultant neurological practice (1961-1991). Epilepsy Research 1994;17:55-79. 4. Raynor RB, Paine RS, Carmichael EA. Epilepsy of late onset. Neurology 1959;9:111q7. 5. Sumi SM, Teasdale RD. Focal seizures. A review of 150 cases. Neurology 1963;13:582-86. 6. Gowers WR. Epilepsy and other chronic convulsive diseases: their cause, symptoms and treatment. London, J & A Churchill, 1881. 7. Rasmussen T. Seizures with local onset and elementary symptomatology. In: Vinken PJ, Bruyn GW (eds) Handbook of Clinical Neurology 1974; 15:74-86. 8. Mathieson G. Pathology. In: Laidlaw J, Richens A, Chadwick D (eds) A textbook of epilepsy. 4th edn. Edinburgh, Churchill Livingstone, 1993;221-40.

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