Medial Medullary Syndrome: Report of 18 New Patients and a Review of the Literature. ,, . Stroke. 1995;26:1548-1552
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Abstract
Background and Purpose With advanced imaging
techniques, infarctions occurring in the medulla are now more easily
identified. To date, however, only
approximately 30 cases of medial medullary
infarction syndrome (MMS) have been reported, and the clinical and
radiological
characteristics of MMS remain to be studied.
Methods We studied 18 patients (15 men, 3 women; mean age, 62 years) who had compatible clinical and MRI findings of MMS and reviewed
the previously reported cases.
Results Seventeen patients had
a unilateral lesion usually involving the upper medulla, and 1 had
bilateral lesions. Fifteen patients
had unilateral sensorimotor stroke, while 2
presented with pure motor stroke. The face was usually but not always
spared.
The degree of hemiparesis varied, and a tingling
sensation with decreased vibration and position sense was the most
common
sensory manifestation. Two patients had lingual
paresis, and none suffered respiratory difficulties. One patient
presented
with bilateral gait ataxia without sensorimotor
dysfunction. Angiography or MR angiography performed in 9 patients
showed
vertebral artery disease in 6. Three patients
had concurrent lateral medullary infarction, and 1 had a previous
history of
lateral medullary syndrome. The prognosis was
generally good, although residual hemiparesis remained in patients with
initially
severe hemiparesis. Review of 26 previously
reported cases showed that they frequently had bilateral lesions, often
presenting
with quadriplegia, lingual paresis, respiratory
symptoms, and a grave prognosis.
Conclusions Our data
illustrate that MMS is most often manifested as benign hemisensorimotor
stroke frequently associated with tingling
sensation and impaired deep sensation. This
benign form of MMS should be much more common than MMS with poor
prognosis and
may have been frequently misdiagnosed as
capsular or pontine stroke before the era of MRI.
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A few clinical details
Hemiparesis was the most common clinical manifestation of
MMS; 15 had contralateral hemiparesis, and 2 (patients 15 and 13)
had ipsilateral hemiparesis and crural
monoparesis, respectively. One (patient 12) did not have motor weakness
but had transient
bilateral gait ataxia. In 2 (patients 5 and
14), motor weakness was the only clinical manifestation (pure motor
stroke), although
patient 5 had slight residual sensory
symptoms due to previous LMS. At the peak of the weakness, the degree of
the hemiparesis
(motor power of the proximal limbs) was
severe (0 to 2 on a scale of 5) in 3, moderate (3 on a scale of 5) in 5,
and mild
(4 or clumsiness on a scale of 5) in 9.
Generally, the distal part of the limb (hand and foot) was more severely
affected
compared with the proximal part. In patients
with significant motor deficit, the progression of weakness usually
evolved for
several hours or days. During this
progression, muscle tone was generally flaccid but became spastic during
the recovery phase.
Hemisensory symptoms were the
second most common clinical manifestation, occurring in 15 patients
(including 3 with LMS).
Initially, 12 patients felt tingling or a
numb sensation. The face was usually spared, but the area of paresthesia
occasionally
ascended to the periotic area (patients 3 and
11) or even to the midface (patients 9, 16, 17, and 18). Vibration
sense was
impaired in 14 patients, and decreased
position sense was noted in 10. However, only 1 (patient 16) had
severely decreased
position sense, and none described the
vibration sense as reduced more than 50% of the intact side. Seven
patients without
LMS stated that the pinprick sense was also
mildly impaired.
Headache (3 cases) and
nausea/vomiting (3 cases) were uncommon, and dizziness/ vertigo was noted
in 9 patients. One (patient
18) had transient ipsilateral lingual
paresis, and patient 3 showed clumsy tongue movements bilaterally.
Including these 2
patients, 4 without LMS had dysarthria, while
2 (patients 2 and 18) had dysphagia. Mild facial paresis was noted in 4
patients.
None had respiratory disturbances. One had
horizontal nystagmus, 1 had upbeat nystagmus, and 1 had both. Patient 16
had transient
gaze paresis and long-lasting sixth nerve
palsy.
The patients were followed up for
14 days to 41 months (mean, 11 months). None died during the follow-up
period. All were
able to walk unassisted, although mild
residual paresis remained in patients with initially moderate to severe
motor weakness.
Uncomfortable paresthesia over the palm or
foot became the most distressing symptom in some patients (patients 9,
11, 16,
and 17).
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Lingual paresis
Unexpectedly, lingual paresis, described in 12 of 26 cases reported in
the literature, was observed in only 2 of our patients,
with the lesions extending dorsally. Lingual
paresis is caused by lesions extending into the lateral part of the
medulla,
affecting the fibers of the hypoglossal nerves
or fascicles, or lesions extending deep into the hypoglossal nucleus.
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Differences from previous reports
The paucity of lingual paresis
and respiratory symptoms along with the
patients’ benign outcome was strikingly different from previously
described subjects
in whom prognosis was generally poor.
These differences may be explained in
several ways. First and most importantly, the diagnosis of MMS was made
by MRI in our
patients, whereas that of most of the previously
reported cases was based on autopsy. Second, since hypertension seems
to
be more prevalent and large-vessel
atherosclerosis less common in oriental than Western countries,
relatively small vessels
might have been more often affected in our
Korean patients than in previously reported cases. Finally, it may also
be possible
that the recent progress on risk factor
management has led us to encounter more benign cerebrovascular diseases
today than
before.
