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Bilateral asterixis in frontal tumor.

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NOTES AND LETTERS
Bilateral Asterixis
in Frontal Tumor
Shosaku Noda, MD,
and Hirotoshi Umezaki, M D
Bilateral asterixis is commonly regarded as a reliable sign of
metabolic encephalopathy [2]. W e describe a patient with
bilateral asterixis resulting from a large frontal tumor. Our
case emphasizes that the presence of bilateral asterixis does
not always rule out a mass lesion.
A 42-year-old woman was admitted to our clinic because
of headache and drowsiness. A computed tomographic (CT)
scan showed a ring-enchancing cystic mass in the left frontal
lobe, and a diagnosis of brain abscess was made. Penicillin,
glycerol, and betamethasone were administered. Two weeks
later she became alert and her headache disappeared. However, five weeks later the headache recurred. She was
oriented but obtunded. H e r blood pressure, pulse, respiration, and body temperature were unremarkable. H e r pupils
were 2 mm in diameter and reacted to light. Ocular movements were intact. No muscle weakness was noted. Hyperreflexia was present in her four limbs. A striking finding was
the presence of asterixis involving both hands and feet. The
asterixis was asynchronous but symmetrical. Serum hepatic
enzymes, blood ammonia, serum creatinine, blood urea nitrogen, serum electrolytes, and blood gas levels were normal,
as was serum osmotic pressure. She was not taking any anticonvulsant agents. A C T scan showed a large cystic tumor in
the left frontal lobe and marked midline shift with compression of the left ventricle. A left frontotemporal craniotomy
was performed. An olfactory neuroblastoma with a large cyst
in the left frontal lobe was confirmed. The cyst was filled
with a yellowish transparent fluid and was totally removed.
The next day she became alert but the asterixis in her right
limbs persisted. Two days after operation the asterixis
cleared.
Our patient developed bilateral asterixis when the clinical
signs and C T scan suggested bilateral hemispheral dysfunction or impaired function of the diencephalon. Metabolic and
toxic factors were excluded. The asterixis resolved after the
operation. These observations indicate that the bilateral asterixis was caused by the frontal tumor.
Only three cases with bilateral asterixis and structural lesions have been reported previously 12-41, Weinreb and
colleagues [4] reported a case of bilateral asterixis and hydrocephalus caused by midline frontal hemorrhage but the patient had received phenytoin, which accentuates asterixis.
Bril and co-workers f l } described it in a patient with midbrain infarction. The ocular signs in their patient suggested
bilateral perinuclear lesions in the rostral midbrain. Santamaria and colleagues [ 3 ] presented a patient with bilateral
asterixis caused by a large left subdural hematoma. The C T
scan of their patient showed marked midline shift as in our
patient.
Unilateral asterixis has been described with structural lesions involving the parietal lobe, thalamus, or midbrain [2].
Although the pathophysiological nature of asterivis is not
clear, dysfunction of these structures may be responsible. In
our patient the bilateral asterixis seems to result from bilat-
366
eral hemispheral or diencephalic impairment caused by the
large frontal tumor.
Department of Neurology
Kyushu-Kosei-Nenkin Hospital
2-1-1 Kishinoura, Yahata-Nishiku
Kitakyushu, 806
Japan
Rejereences
1. Bril V, Sharpe JA, Ashby P: Midbrain asterixis. Ann Neurol
6:362-364, 1979
2. Plum F, Posner JB: The Diagnosis of Stupor and Coma. Philadelphia, Davis, 1980, pp 191-192
3. Santamaria J, Graus F, Genis D: Bilateral asterixis in unilateral
subdural hematoma. J Neurol 229:87-89, 1983
4. Weinreb WH, Perry RJ, Jenkyn LR:Rhythmic alternating asterixis. J Neurol Neurosurg Psychiatry 45:857-858, 1982
The Effects of TRH
on F Waves Recorded
from Antagonistic Muscles
in Human Subjects
Paul J. Delwaide, MD, and J. Schoenen, M D
Thyrotropin releasing hormone (TRH) has been demonstrated in the ventral horn of the cervical and lumbar enlargement of the spinal cord by radioimmunoassay and immunohistochemical methods [ 5 ] . It can also be detected in
the cerebrospinal fluid. Its functional role remains a matter
of speculation. It has been claimed that TRH facilitates
noradrenergic and serotoninergic transmission, but few
neurophysiological studies have explored its mode of action
at the spinal level. In animal experiments [l], TRH depolarizes motoneurons slightly but it is not yet known if this
effect is direct (on motoneuronal membranes) or indirect
(e.g., through interneurons or by facilitation of neurotransmitter activity).
Motor effects of TRH are of great interest to neurologists
because of its potential therapeutic benefit to patients with
amyotrophic lateral sclerosis [ 3 ] and spinocerebellar degenerations [6]. In an attempt to understand more about the
possible functional role of this peptide, we were interested to
see if TRH modifies the F wave in normal human subjects.
The F wave is a muscle response produced by antidromic
activation of motoneurons following peripheral nerve stimulation; F waves are thought to reflect excitability of the motoneuron pool [4]. We have previously shown that TRH enhances the F wave in the musculus flexor hallucis brevis
(FHB) and that 200 pg is the optimal dosage to modify it 121.
The present study was conducted in parallel on two antagonistic muscles, the FHB and the extensor digitorum brevis
(EDB) in order te explore mechanisms that underlie TRHinduced modifications of motoneuronal excitability. If T R H
acts directly on motoneuronal membranes, one would expect
similar effects on antagonistic motoneurons.
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frontal, asterixis, bilateral, tumors
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