close

Вход

Забыли?

вход по аккаунту

?

Diffuse involvement in progressive aphasia.

код для вставкиСкачать
cases the attempt to answer this question can be therapeutically misleading. The clinical manifestations of seizures
reflect the end result of abnormal discharges through local
and widely distributed neuronal circuits and cannot be used
alone to determine precisely where discharges originate
within those circuits. Stimulation and recording through surface and depth electrodes in this and similar cases often suggest two possibilities: either there are several “independent
foci” (in this case amygdala, hippocampus, occipital cortex) or
the abnormality becomes intrinsic to the circuits, with many
anatomically different but pathophysiologically equivalent
points of entry. Recent studies in experimental epilepsy reveal intense orthodromic and antidromic interaction between
a focus and distant sites, where physiological and metabolic
changes can be as intense as in rhe focus itself { 2 , 4 , 6 , 7 ) . In
the case described by Olivier ec al, in which there is interaction between neocortex and limbic cortex, it seems impossible to determine the focus, and thus perhaps it is conceptually misleading to label different areas as primary or
secondary.
The second question is, where is the pathological focus? To
a certain degree, the therapeutic success of surgery for
epilepsy depends upon removing a pathological focus, i.e.,
tumor, AVM, “scar,” and so forth. In this case there appeared
to be no radiographic or pathological evidence for an anatomical lesion, although the authors mentioned neuron loss and
gliosis within the resected temporal lobe. It would be instructive to know the anatomical sites of this damage to learn
whether they lay within the major occipital-limbic pathways
entering hippocampus through entorhinal cortex. Intense seizures in experimental animals can cause distant lesions, or
“double pathology” within seizure pathways 11, 81, but this
has not been critically examined in human beings f3].
Finally, what can be done for the patient? A remarkable
and important aspect of this case was the decision to operate
without unequivocal evidence for a single or dominant
epileptic or pathological focus. Complicated or unclassifiable
cases of epilepsy probably include similar patients with a unilateral neocortical-limbic cortical seizure disorder. The authors have demonstrated that careful electrographic evaluation and temporal lobe resection can be beneficial.
Department of Neurology
Washington University School of Medicine
St. Louis, M O 63110
Refeerences
1. Collins RC, Olney JW: Focal Cortical seizures cause distant
thalamic lesions. Science 218:177-179, 1982
2. Collins RC, Olney JW, Lothman EW: Metabolic and pathological
consequences of focal seizures. In Ward AA Jr, Penry JK, Purpura D (eds): Epilepsy. New York, Raven, 1983, pp 87-107
3. Glaser GH: Treatment of intractable temporal lobe-limbic
epilepsy (complex partial seizures) by temporal lobectomy. Ann
Neurol 8:455-459, 1980
4. Gutnick MJ, Heinemann V, Lux HD: Stimulus induced and seizure related changes in extracellular potassium concentration in
cat thalamus (VPL). Electroencephalogr Clin Neurophysiol 47:
329-344, 1919
5. Olivier A, Gloor P, Andermann F, Ives J: Occipitotemporal
epilepsy studied with stereotaxically implanted depth electrodes
and successfully treated by temporal resection. Ann Neurol
111428-432, 1982
224
Annals of Neurology
Vol 13 No 2
February 1983
Rosen AD, Vastola EF, Hildebrand ZJM: Visual radiation activity
during a Cortical penicillin discharge. Exp Neurol 40: 1- 11, 1973
Schwartzkroin PA, Mutani R, Prince DA: Orthodromic and antidromic effects of a cortical epileptiform focus on ventrolateral
nucleus of the cat. J Neurophysiol 38:795-811, 1975
Sloviter RS, Damiano B P Sustained electrical stimulation of the
perforant path duplicates kainate-induced electrophysiological effects and hippocampal damage in rats. Neurosci Lett 24:279-284,
1981
Reply
AndrC Olivier, MD, Pierre Gloor, MD,
and Frederick Andermann, M D
W e thank Dr Collins for his comments. The questions that he
raises cannot be answered in the case presented. He emphasizes the need for constant correlations between clinical and
laboratory data in order to shed some light on the true mechanisms responsible for seizure manifestations.
Montreal Neurological Hospital
3801 University Ave
Montreal, Que, Canada H3A 284
Diffuse Involvement
in Progressive Aphasia
Norman L. Foster, MD, and Thomas N. Chase, MD
We are concerned about the extent of intellectual disturbance in the aphasic patients described by D r Mesulam 12).
Changes in praxis, calculation, and constructional abilities
were all described in some patients. While we agree that
these cases do not represent uniform involvement of the
brain, it is difficult to evaluate the extent and progression of
damage to discrete brain regions. Since aphasia presents a
major obstacle in evaluation of specific intellectual deficits,
more formal psychometric testing, especially for memory,
would have been valuable.
Recently, similar cases of progressive dementia in which
aphasia was the initial and most prominent feature have been
reported by ourselves 111 and others 13). While comprehensive testing in early stages of the disease indicated relative
sparing of other intellectual functions, positron emission tomography revealed that reductions in glucose utilization were
not limited to regions which classically subserve language. In
order to define clinical groups of patients for study before a
final pathological diagnosis can be made, it is important to
determine precisely the relative performance of as many localizable functions as possible. Quantifiable neuropsychological assessment would afford more convincing evidence that
the patients presented by Mesulam were not, in fact, subject
to a dementing process.
Experimental Therapeutics Branch
National Institute of Nezrrological and Communicative Disorders
and Stroke
National Institutes of Health
Bethesda, M D 20205
Refrencej
1. Foster NL, Patronas NJ, DeLaPaz R, et al: PET studies of Alzheimer disease. Neurology (NY) 32:A167, 1982
2. Mesulam M-M: Slowly progressive aphasia without generalized
dementia. Ann Neurol 11:592-598, 1982
3. Wechsler AF, Verity MA, Rosenschein S, Fried I, Scheibel AB:
Pick's disease: a clinical, computed tomographic, and histologic
study with Golgi impregnation observations. Arch Neurol 39:
287-290, 1982
Reply
M.-Marsel Mesulam, MD, and Sandra Weintraub, PhD
Drs Foster and Chase state concern about the specificity of
the clinical deficits described in our paper [3} and stress the
need for additional neuropsychological testing. The published information, as well as additional unreported data,
however, indicate that the pattern of impairment in our patients was selective rather than diffuse. For example, at a time
when she was profoundly aphasic, Patient 1 had a performance I Q of 123 (untimed), scored in the 95th percentile in
the Raven Standard Progressive Matrices, and in the design
subtest of the Wechsler Memory Scale (WMS) obtained a
score of 11/14, which is well above average for her age (69
years). Despite a severe anomic aphasia which allowed him to
name only 5 of the 85 items in the Boston Naming Test,
Patient 2 had a performance IQ of 125 and obtained a perfect
score in the nonverbal subtests of the WMS. These two patients illustrate the remarkable specificity found in the pattern of cognitive impairment.
Formal neuropsychological testing, although crucial for
defining the extent of mental state impairment, may occasionally lead to misinterpretations in aphasic and apraxic patients.
For example, Patient 5 could not verbally answer questions of
temporal and spatid orientation, even when presented with
multiple choices. O n the other hand, he pointed to the correct date when shown a calendar and to his precise location
when given a map. Another patient performed poorly when a
verbal subtest of the WMS was administered in its customary
oral format but showed perfect learning when allowed to
write down the answers. Substantial modification in testing is
necessary in order to assess intermediary cognitive processes
in patients who have impairments of the relevant input or
output channels. Otherwise, a tabulation of conventionally
obtained scores could lead to the erroneous impression of
more widespread deficits. Neuropsychological testing of our
patients showed that the impairment of language was great,
whereas other functions such as memory, reasoning, and
visuospatial skills remained relatively preserved for many
years during the course of this condition. In addition to cognitive impairments, disturbances in comportment, affect,
judgment, and insight underlie many of the behavioral problems so characteristic of dementia. By contrast, our patients
showed sound judgment and insight and remained independent in daily living activities for many years while the aphasia
progressed relentlessly.
Drs Foster and Chase point out that some of our patients
also showed impairment of praxis and calculations. Apraxia is
a frequent finding in aphasic patients, and praxis and language
may share a common neural substrate El]. Moreover, dyscalculia is often seen with posterior perisylvian (angular gyrus)
lesions in the left hemisphere. Thus, the presence of ideomotor apraxia and dyscalculia is quite compatible with selective involvement of the left perisylvian region, at least until
the terminal stages, when additional disturbances of cognition and comportment may also have emerged in two of
our patients.
The anatomical organization of complex behaviors can be
conceptualized in terms of overlapping cortical networks 121.
The components of each network are tightly interconnected,
and each component belongs to more than one network.
Consequently, even focal lesions are expected to yield partial
deficits of several complex functions. Furthermore, in jury to
a single component is likely to influence the neural activity of
distant areas with which it has the strongest interconnectivity.
It is therefore not surprising to see that patients with major
language involvement also have deficits of praxis and calculation. Nor is it surprising that the depression of glucose metabolism spreads beyond the area of principal tissue involvement. In fact, one of the potential uses of positron emission
tomography could be to reveal the distribution of metabolic
depression elsewhere in the brain after focal primary lesions.
It is our prediction that this distribution will reflect cortical
connectivity patterns.
Wechsler et al [5] recently reported apatient with a similar
clinical picture whose postmortem examination revealed
changes of Pick's disease. Nevertheless, aphasia as the salient
feature is rare in that disorder. In fact, primary deficits of
comportment commonly dominate the clinical picture even
in patients in whom atrophy is most pronounced in the left
temporal lobes. Thus, in 32 cases of Pick's disease, Tissot et a1
141 found that aphasia was the presenting disturbance in only
1 patient. It remains to be seen whether all patients with the
syndrome of progressive aphasia will be examples of an unusual presentation of Pick's disease or whether alternative
pathological processes will also be reported, leaving the pattern of predilection and the indolent course as the major
biological common denominators.
Behavioral Neurology Section, Harvard Neurology Department
Beth Israel Hospital
Boston, M A 02215
References
1. Kertesz A, Hooper P: Praxis and language: the extent and variety
of apraxia in aphasia. Neuropsychologia 20:275-286, 1982
2. Mesulam M-M: A cortical network for directed attention and
unilateral neglect. Ann Neurol 10:309-325, 1981
3. Mesulam M-M: Slowly progressive aphasia without generalized
dementia. Ann Neurol 11~592-598, 1982
4. Tissot R, Constantinidis J, Richard J: La maladie de Pick. Paris,
Masson, 1975
5. Wechsler AF, Verity MA, Rosenschein S, Fried I, Scheibel AB:
Pick's disease: a clinical, computed tomographic, and histologic
study with Golgi impregnation observations. Arch Neurol
39~287-290, 1982
Notes and Letters
225
Документ
Категория
Без категории
Просмотров
0
Размер файла
249 Кб
Теги
diffuse, progressive, involvement, aphasia
1/--страниц
Пожаловаться на содержимое документа