217

Involuntary Tonic Spasms of a Limb Due to a
Brain Stem Lacunar Infarction
David K. Kaufman, MD; Robert D. Brown, Jr, MD; William E. Karnes, MD

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Background and Purpose Although repetitive involuntary
movements are a well-recognized manifestation of carotid
occlusive disease, similar movements have not been reported
with a lacunar infarction outside of the basal ganglia or
subthalamic nucleus. We describe a man with tonic spasms
associated with a lacunar infarction in the right ventral pons.
Case Description Involuntary tonic spasms of a paretic limb
developed acutely in a 69-year-old hypertensive man with a
clinical presentation of pure motor hemiparesis. Magnetic
resonance imaging demonstrated a lacunar infarction of the

ventral pons. There was no evidence for carotid occlusive
disease. An electroencephalogram recorded during the movements showed no abnormality. The abnormal movements
responded well to treatment with oral diazepam.
Conclusions A brain stem lacunar infarction may be associated with involuntary tonic limb spasms clinically similar to those
reported as paroxysmal symptoms of multiple sclerosis. (Stroke.

I

Examination revealed an alert, overweight man with
a resting blood pressure of 172/88, no cardiac murmurs,
and no carotid bruits. There was a mild to moderate left
hemiparesis of the arm and face, with the leg only mildly
affected. Mild hyperreflexia, pronator drift, and a Babinski sign were present on the left. The speech was
mildly dysarthric, and tandem gait was impaired. The
remainder of the neurological examination was normal.
Laboratory studies on admission, including complete
blood count, electrolytes, glucose, prothrombin time,
and partial thromboplastin time, were normal. A computed tomographic scan of the head was normal. The
patient was started on intravenous heparin. During the
hospitalization, several periods of abnormal movement
of the left leg were observed. These were 2- to 3-second
episodes of sudden-onset, stereotyped, tonic contractions of the agonist and antagonist muscles of the
proximal and distal left lower extremity. While supine,
the muscles of the limb would suddenly contract synchronously with the hip and knee remaining extended
and the ankle becoming plantar extended. The movement repeated every 30 seconds regardless of position
and was present when the patient attempted to ambulate. During the movements, there was no change in the
patient's level of consciousness or mental status, and the
left upper extremity was unaffected. Between the
spasms the leg returned to baseline. This activity was
temporarily abolished with a 5-mg dose of oral diazepam but returned a few hours later.

nvoluntary movements due to cerebral ischemia
have been documented in previous reports. 15
These phenomena have been attributed to intermittent cerebral ischemia due to carotid occlusive disease. To our knowledge, there have been no prior
reports of involuntary movements due to a lacunar
infarct that does not involve the basal ganglia or subthalamic nucleus. We report a case of involuntary tonic
spasms of a mildly paretic limb due to a pontine lacunar
infarction.

Case Report
The patient was a 69-year-old right-handed man with
treated hypertension, coronary artery disease, and a
25-pack-year history of smoking. His symptoms began
when he awoke with a dull occipital headache 4 days
before admission. During that and subsequent days he
was aware of gait difficulty and intermittent weakness of
the left upper extremity. Family members noticed that
the left side of his mouth drooped and his speech was
different. During the 2 nights before admission, he was
unable to sleep because of brief, painless, intermittent
"jerks" of his left leg that recurred every 30 seconds.
This symptom continued regardless of leg position and
was present when he attempted to ambulate in an effort
to "walk it off." He recalled a brief period when there
was a simultaneous "jerking" of the left shoulder as
well. The right leg was never involved. This activity
resolved almost entirely during the day, only to resume
again at night. He had never experienced similar symptoms previously. He denied loss of consciousness, diplopia, dysphagia, and sensory abnormalities. His only
medication on admission was nifedipine 30 mg daily.
Received July 30, 1993; final revision received September 13,
1993; accepted September 13, 1993.
From the Department of Neurology, Mayo Clinic and Mayo
Foundation, Rochester, Minn.
Reprint requests to Robert D. Brown, Jr, MD, Department of
Neurology, Mayo Clinic, Rochester, MN 55905.

1994;25:217-219.)

Key Words • brain stem • lacunar infarction • motor
activity

An electroencephalogram (EEG) while awake and
asleep was performed with a surface accelerometer
attached to the left tibialis anterior muscle (Fig 1). The
recorded movements were not associated with any
change in the EEG. Carotid ultrasound and Doppler
examinations of the vertebral arteries were normal. A
transthoracic echocardiogram was normal. A magnetic
resonance imaging (MRI) examination of the head with
gadolinium (Fig 2) revealed a discrete focus of increased T2 signal within the ventral right pons consistent with a lacunar infarction. There were several other

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Stroke Vol 25, No 1 January 1994

PERIODIC LEFT LEG MOVEMENTS
M Age: 75

3-25-93

The intravenous heparin was stopped, and the patient
was dismissed on one aspirin daily. The tonic spasms
became less frequent during 3 days of hospitalization
and ceased altogether after the first night at home.

Discussion

5O|JV

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1 sec
FIG 1. An electroencephalogram (EEG) while awake and
asleep was normal. The EEG was performed with a surface
accelerometer placed on the left tibialis anterior muscle. Tonic
spasms as reflected on the accelerometer were unassociated
with any electrographic discharge on the EEG.

much smaller areas of increased T2 signal within the
white matter of both cerebral hemispheres that were of
uncertain significance. No other areas of infarction were
noted.

Repetitive involuntary movements (RIMs) are a
well-established manifestation of carotid artery disease. Fisher1 first described involuntary motor manifestations of transient ischemic attack (TIA) such as
"trembling, shaking and twisting" of an affected body
part, emphasizing that such movements were not
convulsive in nature. Others have reported the clinical
characteristics and surgical outcomes of patients with
RIMs associated with severe carotid artery disease.3-4
Clinical features include brief, irregular, or rhythmic
jerking or shaking of extremities contralateral to a
severely stenotic or occluded carotid artery. Postural
dependence, being precipitated by abrupt standing or
walking and relieved by laying supine, has been variably reported. EEGs performed during the symptoms
in two patients revealed focal slowing in an appropriate area but no epileptiform activity. Resolution was
common after surgical correction of the carotid stenosis. The mechanism of the movement disorder was
presumed to be cerebral ischemia. Using cerebral
blood flow studies, Tatemichi et al5 supported this
concept by demonstrating perfusion insufficiency in a
patient at rest with limb-shaking TIAs. The focal
perfusion deficit improved and the patient's symptoms
resolved after carotid endarterectomy.
Clonic limb movements have been described in patients with basilar artery occlusive disease.6 Ropper
described eight patients with convulsive limb movements, some of which were associated with incontinence, unresponsiveness, and confusion; at least one
patient maintained alertness. Four patients were autopsied; three had extensive pontine infarctions, and

FIG 2. Magnetic resonance image scanning of the head revealed a discrete focus of increased T2 signal within the ventral right pons
consistent with lacunar infarction. Multiple tiny areas of increased T2 signal were noted within the deep white matter bilaterally.

Kaufman et al Tonic Spasms in Lacunar Infarction

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one had an infarct of the midbrain tegmentum. The
other four had radiological imaging with nonlacunar
thalamic or brain stem infarctions. No patients had an
EEG at the time of the movements. The movements
tended to be more prominent on the side contralateral
to the hemiparesis, allowing a hypothesis of ischemia in
the spared corticospinal tract.
Our patient presented clinically with a pure motor
hemiparesis according to the classification of Fisher.7
Chimowitz et al8 demonstrated that such a presentation
is highly predictive of a lesion involving the internal
capsule, corona radiata, or pons. Boiten and Lodder9
also showed the high predictive value of the major
lacunar syndromes as a clinical test for the diagnosis of
lacunar infarcts. These authors distinguished four lacunar syndromes on clinical grounds, which included pure
motor stroke, sensorimotor stroke, pure sensory stroke,
and ataxic hemiparesis including dysarthria-clumsy
hand cases. The MRI of our patient demonstrated an
appropriate lesion of the basis pontis contralateral to
his hemiparesis. The subsequent development of involuntary tonic spasms in the patient's paretic limb might
be attributed to the pontine lacunar infarction that is
both anatomically and temporally correlated. Furthermore, the temporary presence of symptoms that occurred in the patient's paretic arm simultaneously with
the leg spasms further supports this correlation.
The involuntary limb spasms in this patient are in
many ways reminiscent of the tonic seizures experienced
by multiple sclerosis (MS) patients as a paroxysmal
symptom.1016 According to Matthews,10 tonic seizures
are "brief, frequent, often intensely painful episodes in
which the limbs on one side adopted the tetanic posture." The symptoms are often triggered by movement,
sensory stimulation, or hyperventilation and resolve
after a few weeks. The spells are generally stereotyped,
brief (30 seconds or less), and recurrent (up to hundreds
of times per day).11 Osterman and Westerberg13 have
suggested transversely spreading ephaptic activation of
axons within a partially demyelinated lesion of the
central nervous system as a possible mechanism for the
tonic seizures as well as for other paroxysmal disorders
in MS. The symptoms typically respond well to
carbamazepine.14
It is unclear what mechanism caused involuntary
tonic spasms in the paretic limb of this patient with a
pontine lacunar infarction. The absence of any change
on the EEG during a typical spell argues against an
epileptic phenomenon. The involuntary tonic spasms in
this patient are not typical of the rhythmic jerking and
shaking episodes that characterize the RIMs and limbshaking TIAs of carotid occlusive disease.34 Furthermore, the symptoms were not precipitated by assuming
an upright posture, and no evidence was found for
significant carotid artery disease. These features make it
unlikely that this movement disorder was a manifesta-

219

tion of transient cortical or subcortical ischemia. The
involuntary movements in our patient are most similar
to the tonic seizures of MS, although key features of
associated sensory symptoms and triggering factors are
not present. One might envision the lacunar infarct in
this patient causing a disturbance of corticospinal tract
function in the same way an MS plaque would cause an
abnormality in the same location. It unclear whether it
is electrophysiologically possible for an area of infarction (or the surrounding ischemic penumbra) to induce
local ephaptic transmission of otherwise normal axonal
impulses. Alternatively, the lesion may interfere with
descending inhibitory fibers affecting the anterior horn
cells of the involved limb. The therapeutic effectiveness
of the -y-aminobutyric acid-facilitating drug diazepam
would support the theory that the lesion is interfering
with inhibitory control.
Lacunar infarcts are rarely associated with movement
disorders.6 Hemiballismus is classically due to an infarct
of the subthalamic semilunar nucleus of Luys. Acute
dystonia may result from a thalamic lacunar infarction.
To the best of our knowledge, involuntary movements
have not been previously described in association with a
lacunar infarction occurring outside of the basal ganglia.

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