HEMlPLEGlC ATROPHY:
ELECTROPHYSIOLOGICALAND
MORPHOLOGICAL STUDIES
Roberto P. Segura, MD, and Vinod Sahgal, MD

Abstract: A patient with hemiplegic atrophy following

stroke is described. Electrophysiological studies
confirmed the absence of root or peripheral nerve
involvement. Findings of severe muscle membrane
dysfunction and the morphological evidence of
lower motor neuron pathology point to a central
nervous system process as the origin of the observed changes.
MUSCLE 8 NERVE 4:24&248
lS8l

The pathogenesis of hemiplegic muscle atrophy
has been widely speculated. Electrophysiological
data suggest muscle membrane dysfunction.
We report here a detailed electrophysiological
study of hemiparetic limbs following stroke, along
with morphological substantiation of lower motor
neuron involvement.
CASE REPORT

The patient, a 30-year-old right-handed woman,
had a 13-year history of intermittent nausea, vom-

From the Department of Neurology, Northwestern University Medical
School, Chicago. IL.
Acknowledgments: Or. Marshall Sparberg kindly allowed us to perform
sequential electrodiagnostic testing on his patient.
Address reprint requests to Dr. Segura at the Department of Neurology,
Northwestern University Medical School, 320 East Superior, Chicago, IL
6061 1.
Received for publication January 24, 1980; revised manuscript accepted
for publication July 16, 1980
0148639X/0403/0246 $01.25/0
1981 John Wiley B Sons. Inc.

246

Hemiplegic Atrophy

iting, diarrhea, and anorexia. A diagnosis t)f
Crohn's disease was entertained but never confirmed by either repeated x-ray examinations or
exploratory laparotomy. During a recent episode
of nausea and vomiting, she entered the hospital
to undergo a course of hyperalimentation via
the right subclavian vein. Following the insertion of the subclavian line and during the subsequent days, she experienced occasional discomfort in the substernal area related to activity and
lasting for periods ranging from 5 to 30 minutes.
On her fifth day of hospitalization, she noted
greater substernal distress along with severe
pain, lightheadedness, perspiration, and dyspnea.
Shortly thereafter, she developed severe pain in
her left arm followed by transient confusion and
tonic clonic movements of the left arm and leg.
Neurological examination immediately after this
episode disclosed a left spastic hemiparesis, in
which the arm was affected more than the leg, mild
left facial weakness of upper motoneuron type, left
anosagnosia with neglect of the entire left side of
her body, and a left visual field cut. Deep tendon
reflexes were increased in that side, and a left extensor plantar response was present. Diagnostic
studies revealed bilateral temporal slowing on
electroencephalogram; a technetium brain scan
showed a right frontoparietal uptake. The results
of C T scan, 4-vessel cerebral angiography, blood
analyses, and cerebrospinal fluid analysis were unremarkable. A diagnosis was made of embolic infarction in the distribution of the right middle cerebral artery. Tests for collagen vascular disease,
lupus, or porphyria, among other possible underlying causes, were negative.
ELECTRODIAGNOSTIC STUDIES AND
MUSCLE BIOPSY

Electrophysiological studies were performed at 1,

2, 5, and 24 months following onset of the ictal
episode.

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May/Jun 1981

Figure 1 . Biopsy of the left vastus lateralis muscle (myosin ATfase) showing small angular fibers, fiber-type grouping, and grouped
atrophy (pH 9.4). Magnification x250. Bar = 40 ~ y n .

Motor conduction velocities of the left median
and ulnar nerves (including conductions of distal
segments and across the axilla, as well as F-wave
latencies) and the peroneal and posterior tibia1
nerves, and sensory conduction velocities of the
left sural, median, and ulnar nerves were normal
on repeated testing. Distal and proximal muscles in
the right arm and leg, as well as cervical and lumbar paraspinal muscles, revealed no electromyographic alterations.
Electromyography revealed the following alterations in several representative muscles.
(I) At 1 month, there was mild to moderate
spontaneous activity at rest (positive sharp waves
and fibrillations) and a slight increase of small
polyphasic voluntary motor unit potentials (MUPs)
in the left extensor digitorum brevis muscle; moderate to marked spontaneous activity and no voluntary MUPs in the left first dorsal interosseous
muscle; and mild spontaneous activity with an increase in small polyphasic voluntary MUPs in the
left biceps and vastus medialis muscles.
(2) At 2 months, there was marked spontaneous
activity at rest and no voluntary MUPs in the extensor digitorum brevis muscle; marked spontaneous activity and no voluntary MUPs in the first
dorsal interosseous muscle; and moderate spontaneous activity with an increase in small polyphasic voluntary MUPs along with a reduction in

Hemiplegic Atrophy

number of motor units in the biceps and vastus
medialis muscles.
( 3 ) At 5 months, there was no spontaneous activity at rest in any muscle sampled. There was an
increase in large and polyphasic voluntary MUPs,
with reduced number in the extensor digitorum
brevis and first dorsal interosseous muscles, and a
slight increase in large polyphasic voluntary MUPs,
with slight reduction in number in the biceps and
vastus medialis muscles.
(4) At 24 months, there was no spontaneous activity at rest and an increase in large or slightly
large voluntary MUPs, greater in distal muscles.
Recruitment was normal or borderline. At this
time, strength was back to normal in all muscles,
except for mild weakness in the extensor muscles
of the left hand and foot.
Although no measurements of the limbs were
carried out, there was visual evidence of atrophy in
distal muscles, more noticeable by the 5th month.
A return of bulk was noted at the time of our last
examination. Deep tendon reflexes remained
slightly increased in the left arm and leg.
A biopsy of the left vastus lateralis muscle was
obtained 4% months following onset of the illness
(Fig. 1). Care was taken not to biopsy a previously
needled area. N o injections had been given
previously in that muscle. The specimen revealed extreme variation in fiber size. There were

MUSCLE B NERVE

May/Jun 1981

247

groups of very small atrophic fibers (less than
20pm in diameter), a moderate increase in internal
nuclei, as well as some fiber splitting. Histochemical stains showed scattered angular fibers, fibertype grouping, grouped atrophy, and target fibers.
These changes were compatible with a significant
degree of neurogenic atrophy.
DISCUSSION

The patient described here showed unique electrophysiological alterations detected through serial
studies performed after a stroke. These were more
prominent during the first 2 months and slowly
disappeared by the 24th month. The muscle biopsy
at 4% months showed grouped atrophy, angular
fibers, and target fibers, all considered to be
pathognomonic of denervation. Fiber-type grouping suggested ongoing reinnervation.
Clinical observations of atrophy in hemiplegic
limbs in association with cerebral lesions have been
reported .RJ6Morphological changes in the muscle
have also been described following ~ e r e b r a l and
~.~
spinal cordlSlesions. Electrodiagnostic studies have
revealed the presence of positive sharp waves and
fibrillations in hemiplegic limbs 1 to 3 weeks following ~ t r o k e , ~ * ~although
J ~ J ~ J ~no serial testing
has been performed. These reports provided no
data on motor unit alterations. Other observers
have failed to detect such spontaneous discharges'
or, if they did find such discharges, they considered them to be secondary to subclinical neuropathy or brachial plexopathy in the involved
limbs.3
The absence of nerve conduction alterations in
our patient speaks against brachial plexus or peripheral nerve dysfunction. Furthermore, the reduction in the neuropathic pattern and return to
near normalcy in 24 months with normal nerve
conduction velocities and F-wave latencies is unusual for a neuropathy. The muscle biopsy
findings of grouped atrophy, angular fibers, and
fiber-type groupings are again suggestive of a
neurogenic process. In disuse atrophy, fiber-type
grouping is not a feature, even though nonspecific
variable degrees of atrophy have been reported
e~perimentally.~
Hemiplegic patients who use
neither their paretic nor their uninvolved limbs
have been noted to have significantly more profound atrophy on the paretic side.13
Our electromyographic and pathologic findings suggest a neurogenic process. The question

248

Herniplegic Atrophy

of the source of this neurogenic influence now
arises. Normal nerve conduction velocities and
F-wave latencies negate the role of anterior root
and peripheral nerve. On the other hand, the alterations noted in the involved limbs suggest a
neurotrophic influence being exerted directly
from cerebral structures, thought to be precentra16
or ~arieta1.I~
More recent studies have suggested a
transneuronal degeneration of spinal motoneurons following destructive lesions of descending
motor pathways.12

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