The Journal of the Arkansas Medical Society Med Journal Dec 2019 | Page 15

tient’s cavernoma demonstrated no involvement of
the subthalamic nucleus. While lesions of the sub-
thalamic nucleus have classically been associated
with hemiballismus, several reports in the literature
have demonstrated that damage to several areas
of the basal ganglia can produce this unique clini-
cal disease. 8
Image 1: MRI brain shows cavernous malformation involving the right sub insular region, external
capsule, and right putamen A. T2 weighted sagittal, B. GRE C. T1 post-contrast images.
was started with goal of increasing to 25mg TID.
Blood sugar was also controlled during hospital-
ization with sliding scale insulin regimen. With the
addition of olanzapine and tetrabenazine, patient
reported moderate improvement in her symptoms
and was discharged home. Patient followed up in
neurology clinic one month later with significant
improvement in her symptoms and only mild cho-
reiform movements of her left extremities. She was
advised to continue symptomatic management
with olanzapine and tetrabenazine.
Discussion
The most common cause of hemiballismus
is cerebrovascular disease such as stroke involv-
ing the subthalamic nucleus and other differential
including metabolic disturbances, neoplasms,
or infectious causes. Indeed, given the initial CT
findings, hemorrhagic stroke was one of our first
suspicions for this patient. Less common vascular
causes of hemiballismus include vascular mal-
formations such as arteriovenous malformations
(AVMs), venous angiomas, capillary telangiectasias,
and cavernomas.
Cavernomas, also known as cavernous hem-
angiomas, are benign blood vessel malformations
composed of dilated, thin-walled endothelium
without associated smooth muscle or elastin. They
are estimated to comprise 8-15% of all cerebral
vascular malformations and are most commonly
located in the cerebrum with predominance for
the subcortical temporal and rolandic regions. 3
Cavernomas are often asymptomatic and may be
discovered incidentally or post-mortem. However,
symptomatic cavernomas usually manifest in the
third or fourth decade of life. 4 There is a wide ar-
ray of symptomatology due to variable localization
of the cavernoma. Common manifestations include
hemorrhage, seizure, and progressive neurological
deficits. These manifestations are believed to be
NUMBER 6
due to hemorrhage, mass effect, and irritation of
brain tissue from hemosiderin deposits. Although
cavernomas occur with equal frequency in males
and females, it is important to note that women
are more likely to present with hemorrhage and/or
neurologic deficits. 5
Diagnosis of cavernomas requires adequate
and appropriate neuroimaging. As symptoms may
present abruptly and mimic stroke, brain CT is
often the initial imaging modality utilized. CT will
usually reveal an area of non-specific hyperdensity
with or without areas of calcification. Since blood
flow through cavernomas is minimal, angiogra-
phy usually reveals no abnormalities and is rarely
helpful in diagnosis. MRI is the imaging modality
of choice and usually establishes the diagnosis of
cavernoma. 6 MRI findings include T1W and T2W
variable hyperintensities that may be surrounded
by a hypointense “ring” representing previous
hemorrhage. The cavernoma in our case was ini-
tially evaluated by CT and thought to represent
either hemorrhage or neoplasm. It was not until
MRI imaging was obtained that the diagnosis of
cavernoma became evident. Therefore, timely MRI
evaluation is essential to early diagnosis and man-
agement.
In our case, we believe the symptomatic
transformation was likely due to bleeding in the
cavernoma, as there was evidence of previous
hemorrhage on imaging. However, metabolic dis-
turbances from hyperglycemia may also have con-
tributed to our patient’s presentation. Nonketotic
hyperglycemia is the second-most-common cause
of hemiballismus and is often seen in patients with
very poorly controlled diabetes. 7 Given our patient’s
HbA1c of 14.9% and hyperglycemia at presenta-
tion, it is possible that hyperglycemia resulted in
additional cumulative insult to the basal ganglia
that ultimately led to her symptomatic transforma-
tion. Additionally, it is important to note that our pa-
In conclusion, cavernomas may rarely cause
symptoms of chorea or hemiballismus. In such
cases, MRI is the imaging modality of choice and
will usually demonstrate a lesion localized to the
basal ganglia.
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