Arq. NeuroPsiquiatr. vol.50 número4

SEGMENTAL MYOCLONUS AND BASILAR ARTERY

GIANT ANEURYSM

C A S E R E P O R T

J. PITÁGORAS DE MATTOS * — ANA L. ZUMA DE ROSSO ** EDUARDO ZAYEN ** — SÉRGIO A. P. NOVIS ***

S U M M A R Y — A 7 0 y e a r s - o l d m a n w a s a d m i t t e d a t o u r h o s p i t a l b e c a u s e o f u n s t a b l e a n g i n a p e c t o r i s . H e h a d e s s e n t i a l h y p e r t e n s i o n a n d r i g h t h e m i p l e g i a f r o m a i s c h e m i c s t r o k e t w o y e a r s b e f o r e a d m i s s i o n . O n n e u r o l o g i c e x a m i n a t i o n , i t w a s f o u n d m e n t a l d i s o r i e n t a t i o n , u n s t a b l e e m o t i o n a l i t y , r i g h t s p a s t i c h e m i p a r e s i s w i t h r i g h t B a b i n s k i s i g n , a n d s e g m e n t a l m y o -c l o n u s a f f e -c t i n g t h e s u p e r i o r l i p a n d t h e p a l a t e ( p a l a t a l n y s t a g m u s ) o n t h e r i g h t s i d e . O n t h e C T scan, a g i a n t a n e u r y s m o f t h e b a s i l a r a r t e r y w a s d e t e c t e d . W e c o n c l u d e t h a t t h e s e g m e n t a l m y o c l o n u s c o u l d b e e x p l a i n e d b y i s c h e m i c l e s i o n s i n t h e G u i l l a i n - M o l l a r e t t r i a n g l e .

K E Y W O R D S : s e g m e n t a l m y o c l o n u s , p a l a t a l n y s t a g m u s , b a s i l a r a r t e r y a n e u r y s m .

Mioclonia segmentar e aneurisma gigante da arteria basilar.

R E S U M O — O s a u t o r e s s e r e f e r e m a o c a s o d e u m h o m e m d e 7 0 a n o s , h i p e r t e n s o e c o r o n a -r i o p a t a , q u e a p -r e s e n t a -r a , d o i s a n o s a n t e s , h e m i p l e g i a d i -r e i t a c o m o c o n s e q u ê n c i a d e a c i d e n t e v a s c u l a r e n c e f á l i c o i s q u é m i c o . O e x a m e n e u r o l ó g i c o , n a v i g ê n c i a d a i n t e r n a ç ã o h o s p i t a l a r , m o s t r o u d e s o r i e n t a ç ã o e s p a c i a l , i n s t a b i l i d a d e e m o c i o n a l ( c h o r o i m o t i v a d o ) , h e m i p l e g i a c o m sinal de Babinski à d i r e i t a e m i o c l o n i a s e g m e n t a r c o m p r o m e t e n d o o l á b i o s u p e r i o r e o p a l a -t o ( n i s -t a g m o p a l a -t a l ) à d i r e i -t a . A -t o m o g r a f i a c o m p u -t a d o r i z a d a d o c r â n i o r e v e l o u a n e u r i s m a g i g a n t e d a a r t é r i a b a s i l a r . C o n c l u i m o s q u e a m i o c l o n i a s e g m e n t a r p o d e r i a e s t a r r e l a c i o n a d a à s l e s õ e s i s q u é m i c a s n o t r i â n g u l o d e G u i l l a i n - M o l l a r e t .

P A L A V R A S - C H A V E : m i o c l o n i a s e g m e n t a r , n i s t a g m o palatal, a n e u r i s m a dia a r t é r i a b a s i l a r .

The first reference in the literature about myoclonic jerk was made by

Friedreich, in 1878, naming the abnormal movement as «paramyoklonus

multi-plex)^. Presently, the myoclonus is classified according to its distribution as

focal, segmental, multifocal and generalized 5.

We report on a case of segmental myoclonus (soft palate and lips). During

the investigation it was found to be associated to a basilar artery aneurysm.

A discussion about probable mechanisms of the palatal myoclonus is provided.

C A S E R E P O R T

J R ( R e g 223619-7, H U C F F - U F R J ) , a 7 0 y e a r s - o l d n e g r o m a n , w a s a d m i t t e d a t o u r h o s p i t a l b e c a u s e o f u n s t a b l e a n g i n a p e c t o r i s . H e h a d e s s e n t i a l h y p e r t e n s i o n a n d r i g h t h e m i -p l e g i a f r o m a i s c h e m i c s t r o k e t w o y e a r s b e f o r e a d m i s s i o n . O n n e u r o l o g i c e x a m i n a t i o n , i t w a s f o u n d m e n t a l d i s o r i e n t a t i o n , e m o t i o n a l u n s t a b i l i t y , r i g h t s p a s t i c h e m i p a r e s i s w i t h r i g h t B a -b i n s k i ' s s i g n , a n d s e g m e n t a l m y o c l o n u s a f f e c t i n g t h e s u p e r i o r a n d i n f e r i o r l i p s a n d t h e p a l a t e

(palatal n y s t a g m u s ) o n t h e r i g h t side.. O n t h e C T s c a n , a g i a n t a n e u r y s m o f t h e b a s i l a r a r t e r y w a s d e t e c t e d a s w e l l a s i s c h e m i c l e s i o n s a n d c e r e b r a l a t r o p h y ( F i g s . 1 a n d 2 ) . B e c a u s e o f h i s s e v e r e c a r d i o v a s c u l a r d i s e a s e t h e a n g i o g r a p h i c s t u d y w a s n o t p e r f o r m e d .

D e p a r t m m e n t o f N e u r o l o g y , C l e m e n t i n o F r a g a F i l h o U n i v e r s i t y H o s p i t a l ( H U C F F - U F R J ) , R i o d e J a n e i r o : * A s s o c i a t e d P r o f e s s o r ; * * N e u r o l o g i s t ; *** H e a d o f t h e S e r v i c e o f N e u r o l o g y .

COMMENTS

Segmental myoclonus is characterized by myoclonic jerks affecting two or

more contiguous or adjacent muscles

. Aetiologically, it can be divided in

essen-tial and symptomatic f o r m s

. Regarding to palatal myoclonus the symptomatic

form is more frequent, according to the extensive review of the literature made

by Deuschl et al.

in 1990. They reviewed 287 cases of palatal nystagmus of

which only 27% were essential. In the symptomatic group (73%), 40% were

due to cerebrovascular disease, 8% to trauma, 7% to neoplasia, 3% to multiple

sclerosis, 2% to degenerative disease and 2% to encephalitis. According to

Jankovic and Pardo

, infarction and hemorrhage of the brainstem were the

main pathological cause of palatal myoclonus. It is admitted that palatal

myo-clonus is secondary to a disruption of the dentato-rubro-olivary pathway, known

as the Guillain-Mollaret triangle

"

. The unilateral palatal nystagmus arises from

a lesion in the ipsilateral dentate nucleus or in the contralateral central

tegmen-tal tract and may be associated with a hypertrophic degeneration of the

contra-lateral inferior olive

.

. Furthermore, the only abnormal movement associated

with lesion of the inferior olive is palatal nystagmus

.

The challenge of this case is to know whether the aneurysm is responsible

direct or indirectly for the myoclonus or it is merely a radiological finding.

It seems reasonable that they are related to each other once the cerebrovascular

disease is the most frequent cause of the palatal nystagmus and the

Guillain-Mollaret triangle is closely related with this involuntary movement. What should

be the mechanism by which the aneurysm has induced the involuntary

move-ment: ischemia or mass effect? Teasdall^, in 1958, described a similar case on

which he demonstrated by angiography a posterior fossa arteriovenous aneurysm

in which there was thrombosis of the right vertebral artery. Three months after

the ictus, palatal nystagmus was substituted by right soft palate palsy. In that

occasion, Teasdall has related the myoclonus with the vascular thrombosis.

The direct (ischemic areas on the CT scan, angina pectoris) and indirect

signs of diffuse atherosclerosis in our patient, together with the presence of a

giant aneurysm of the vertebro-basilar system, suggest brainstem ischemic lesions

and not a compressive effect as the probable cause of segmental myoclonus.

REFERENCES

1. Deuschl G, Mischke G, Schenck E, Schult-Mônting J, Lucking CH. Symptomatic and

es-sential rhythmic palatal myoclonus. Brain 1990, 113:1645-1672.

2. Jankovic J, Pardo R. Segmental myoclonus: clinical and pharmacologic study. Arch

Neu-rol 1986, 43:1025-1031.

3. Kissel P, Schmitt J, Andre JM. Syndromes du tronc cérébral. Ehcycl Méd Chir Système

Nerveux 7-1975, 17039A10, Paris: Editions Techniques, 1975.

4. Lee RG. The pathophysiology of essential tremor. In Marsden CD, Fahn S (eds) :

Mo-vement Disorders 2. London: Butterworths, 1987, p 423-437.

5. Patel VM, Jankovic J. Myoclonus. In Appel SH (ed) : Current of Neurology. Chicago:

Years Book Med Publ, 1988, p 109-156.