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Convulsive-like Movements in Brainstem Stroke
Gustavo Saposnik, MD;
Louis R. Caplan, MD
Arch Neurol. 2001;58:654-657.
ABSTRACT
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Background Involuntary convulsive-like movements sometimes occur in patients with
brainstem strokes. These movements vary in nature, frequency, and trigger,
including fasciculation-like, shivering, jerky, tonic-clonic, and intermittent
shaking movements. Some are interpreted as decerebrate postures or seizures.
It is important to recognize this type of motor phenomenon since it may be
a diagnostic clue for early diagnosis and treatment of brainstem strokes.
Design Case report and review of the literature.
Observation A 72-year-old-man presented with impaired consciousness and jerks of
the upper limbs mimicking seizures. These episodes consisted of brief clonic
contractions of the proximal and distal upper extremities. They were observed
in paroxysms lasting for 3 to 5 seconds. Magnetic resonance imaging showed
large midpontine infarction. Magnetic resonance angiography revealed the absence
of basilar artery blood flow. No seizure discharges were observed in the electroencephalogram.
Anticoagulation with intravenous heparin was started. Two days after admission,
the patient had a cardiac arrest and died. We review the frequency and nature
of convulsive-like movements in brainstem stroke in the literature.
Conclusions Movements associated with brainstem lesions are not easily differentiated
from convulsions. Unexpected onset and inexperience of the observers limit
the characterization of this phenomenon. Convulsive-like movements in brainstem
stroke may occur more frequently than reported. Early detection of this motor
phenomenon may have practical implications.
INTRODUCTION
SINCE 1868, spontaneous movements have been described in patients with
brainstem lesions.1, 2, 3, 4
Tonic postures and jerks or twitching of the limbs in stroke patients are
variously reported as seizures or abnormal movements.2, 3
They were originally described in association with decerebration. The movements
often are of sudden onset and may persist for a variable time.
We describe a patient with brainstem ischemia and convulsive-like movements
and review the literature.
REPORT OF A CASE
A 72-year-old man presented with impaired consciousness and "seizures."
He was eating when he suddenly developed weakness on his left side and fell
down. His wife observed tonic postures in the 4 limbs while the patient was
on the floor. Two days before admission, he reported dizziness and the persistence
of visual images even when his eyes were closed. He had a history of arterial
hypertension and hypercholesterolemia. He had no history of migraine, seizures,
or stroke.
In the emergency department, he was immediately connected to a respirator.
On neurological examination, he was quadriparetic and unresponsive. Pupils
were 3 mm and reactive to light. He had rightward gaze conjugate palsy. Lower
brainstem reflexes were present. He had spontaneous jerking of the upper limbs
lasting for 3 to 5 seconds. These episodes consisted of sudden, stereotypical,
brief clonic contractions of the proximal and distal upper extremities. These
movements repeated in paroxysms at irregular intervals regardless of the position
of his arms. They were different from the classic decerebrate posture or myoclonus.
During the movements, there was no change in the level of consciousness. No
movements were detected in the face or lower limbs.
Results of laboratory studies, including complete blood cell count,
electrolyte levels, glucose level, partial thromboplastin time, and prothrombin
time, were normal. An electroencephalogram (EEG) showed no cortical discharges.
A diffusion-weighted magnetic resonance image (MRI) on admission showed a
pontine infarction involving the right basis and the tegmentum (Figure 1 and Figure 2). A magnetic resonance angiogram showed absence of basilar artery blood flow.
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Figure 1. Magnetic resonance image at presentation
showing T2-weighted hyperintense signal affecting the right pons in the base
and tegmentum.
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Figure 2. Diffusion-weighted image sequence
demonstrating marked signal changes in the basis pontis and tegmentum.
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Anticoagulation with intravenous heparin was started. The next day,
the patient was in a coma with no motor response. His pupils were fixed and
nonreactive to light. At that time, a new diffusion-weighted MRI showed a
large midpontine hyperdense lesion involving the bilateral base and tegmentum.
No cerebral lesions were detected. The vertebral arteries in the neck were
normal, suggesting a proximal basilar artery occlusion. He had a cardiac arrest
and died 48 hours later.
COMMENT
We report brief clonic jerking movements that resemble those occurring
in convulsions in a patient with pontine infarction due to basilar artery
occlusion. The MRI and the EEG showed no cerebral abnormalities or discharges.
Curiously, our patient exhibited bilateral arm movements at the time of the
first MRI (when the stroke was asymmetric). We hypothesize that corticospinal
tracts were ischemic bilaterally, although only the right side of the pons
was infarcted. However, it is difficult to understand why the movements were
initially observed in the arms and not in the lower limbs.
Involuntary movements of the limbs are occasionally seen in patients
with acute strokes.5 These movements vary in
nature, amplitude, frequency, and triggers. They include fasciculation-like,
shivering, jerky, tonic-clonic, and intermittent shaking movements. Some movements
are not easily differentiated from convulsions. Witnesses present during the
episodes often report them as "seizures." The spared consciousness and variability
may be evidence against an epileptogenic mechanism. The upper and lower extremities
have been equally involved, and the movements can be unilateral or multifocal.
The rapid and unexpected onset, low incidence, and inexperience of the observers
limit the characterization of this phenomenon.
In 1868, Nothnagel4 described the presence
of a "convulsive pontine center." Later, Jasper and Droogleever6
and Penfield7 postulated a "centrencephalic
system" to characterize a group of neurons located in the midbrain reticular
formation that functioned as a pacemaker for seizures. The role of the brainstem
in the generation of tonic convulsions was studied more than 4 decades ago;
however, the subject is still controversial.8
Experimental evidence in rat and cat models showed that stimulation of the
reticular formation of the midbrain, pons, or medulla results in tonic seizures
with absence of discharges in the cortex or at the site of the stimulus.9, 10 Kreindler et al,9
Bergman et al,11 and others12, 13
showed that brainstem stimulation induced tonic or clonic movements depending
on the magnitude of the stimulating current.
Recently, Kohsaka et al12 studied sequential
changes of brainstem function before and during 3-Hz spike and wave complex
discharges in patients with typical absence seizures using simultaneous auditory
evoked potentials and EEG. They found changes in the wave III component of
the auditory evoked potentials preceding the onset of cortical paroxysmal
discharges. This evidence reintroduced the classic concept of a centrencephalic
system as a seizure-generating mechanism. Similar findings have been obtained
in animals and humans with decreased basilar artery blood flow.13
Table 1 and Table 2 show previous reports of abnormal involuntary movements
in patients with hemorrhagic and ischemic pontine strokes. In 1903, Charles
Dana2 studied 46 patients with pontobulbar
hemorrhages. Three of them had "twitching of the face, or of the limbs or
both." He also noted forced laughter-crying episodes associated with this
motor phenomenon when the contralateral thalamus was involved. Dana and other
authors believed that the abnormal movements observed in pontine lesions were
not convulsive in nature. In 1967, Silverstein14
reported on 50 patients with pontine hemorrhages. Eleven patients (22%) had
"convulsive seizures," 3 of them unilateral. These motor movements were the
initial symptom in 7 patients (63%). Two of 11 patients with unilateral pontine
hemorrhages mainly involving the basis pontis and tegmentum had convulsive
seizures, while 7 of 28 patients with bilateral basis pontis lesions and 2
of 11 patients with tegmental hemorrhages had convulsive seizures. These are
the 2 largest series reporting convulsive-like movements in pontine hemorrhages.
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Table 1. Convulsive-like Movements in Patients With Pontine Hemorrhage
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Table 2. Convulsive-like Movements in Patients With Pontine Infarction*
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In 1951, Cannon3 reported convulsion-like
episodes in 32 (26%) of 122 patients with acute brainstem lesions, most of
them secondary to tumors. Convulsive movements ranged from isolated twitching
of the extremities to generalized seizures. However, only 17 patients (14%)
in that series had basilar artery occlusions, and the frequency of convulsions
was not reported.
Other authors observed similar movements in patients with basilar artery
occlusive disease (Table 2). Kubik
and Adams,18 in their pathological study of
basilar artery occlusions, found 1 patient (case 3) (6%) with convulsive seizures
among 18 individuals studied. Fang and Palmer15
reported clonic movements in 5 of 7 patients, and Siekert and Millikan20 described "twitching of the extremities" in 3 patients
(11%) and generalized convulsions in 1 (4%) of 28 patients with basilar artery
occlusions.
Halsey and Downie16 described 3 patients
with "decerebration rigidity" with spared consciousness. One of these patients
was a 34-year-old woman who presented with occipital headache and vertigo.
Her family observed 3 "severe shaking episodes" with urinary incontinence.
Angiography showed proximal basilar artery stenosis. Silverstein21
analyzed 83 autopsies of patients with pontine infarcts. Eleven (13%) had
basilar artery occlusions. He found 8 individuals who had "convulsive-seizures"
(2 focal, 6 generalized), all of whom had "tremors and clonic jerks of the
muscles of the extremities." The infarct was located in the paramedian area
in 3 patients, in the central tegmentum in 2, and in the tegmentum and basis
pontis in the remaining 3. Miller Fisher17
analyzed transient symptoms in patients with vertebral artery occlusion. In
1 patient, jerkings of the left arm with spared consciousness were observed.
In 1988, Ropper22 reported convulsive-like
movements in 8 patients with basilar occlusions. Autopsy results were available
for 4 patients and showed that the tegmentum was the most commonly affected
area. Magnetic resonance imaging or computed tomographic scans of the head
were performed for the remaining patients. Thalamic, occipital, and pontine
lesions were found in these individuals (Table 2).
Considering all reports that analyzed convulsive-like movements, 66
(23%) of 287 patients with pontine strokes had abnormal movements. The presence
of convulsions was more frequent in patients with pontine infarction (23/91
[25%]) than in those with pontine hemorrhage (14/96 [15%]). However, we cannot
exclude a selection bias, since we only considered those studies reporting
movements in brainstem strokes. Therefore, caution must be taken when interpreting
the real frequency of convulsive-like movements in this condition.
In summary, we believe that the movements in our patient may be related
to ischemia of the corticospinal tracts rather than to true convulsions with
a brainstem nuclear origin. Convulsive-like movements may be seen in patients
with either hemorrhagic or ischemic pontine lesions. Recognition of these
movements may allow earlier diagnosis of pontine stroke. The pathophysiological
mechanisms remain uncertain. Further functional studies are necessary to clarify
the nature of this phenomenon.
AUTHOR INFORMATION
Accepted for publication July 5, 2000.
We thank Jose A. Bueri, MD, for his kind collaboration.
From the Stroke Unit, Department of Neurology, Ramos Mejía Hospital,
Buenos Aires University, Buenos Aires, Argentina (Dr Saposnik); and the Stroke
Unit, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard
Medical School, Boston, Mass (Dr Caplan).
Corresponding author and reprints: Gustavo Saposnik, MD, Charcas
4431 4 "10," Buenos Aires C1425BMN, Argentina (e-mail: gsaposnik{at}intramed.net.ar).
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