(Stroke. 1995;26:1379-1385.)
© 1995 American Heart Association, Inc.
Articles |
From the Departments of Neurology (H.N., C.B.) and Clinical Neurophysiology (H.N., T.K., G.W.), Institute of Clinical Neuroscience, and the Division of Neuroradiology (S.E., C.J.), Department of Radiology, Sahlgren Hospital, University of Göteborg, Sweden.
Correspondence to Hans Naver, Department of Clinical Neurophysiology, Institute of Clinical Neuroscience, Sahlgrenska University Hospital, 41345 Göteborg, Sweden.
| Abstract |
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Methods Temperature perception thresholds, skin temperatures, evaporation rates, and skin blood flow responses were measured bilaterally in 37 stroke patients aged 58±13 years (mean±SD) and in a control group of 15 patients aged 64±15 years with a single transient ischemic attack.
Results Of the 37 stroke patients, 43% reported a sensation of coldness in the contralesional side of the body. Basal skin blood flow and temperature were relatively lower in the contralesional side. There was an excess of evaporation in the contralesional side after brain stem lesions and in the ipsilesional side after hemispheric lesions. Vasomotor reflex asymmetries occurred in 34% of the patients and were due to weak vasodilator or vasoconstrictor reflexes in the ipsilesional side. These abnormalities correlated significantly to sensations of unilateral coldness, hypalgesia, and thermohypesthesia in the contralesional side and anatomically to lesions in spino-thalamo-cortical pathways.
Conclusions Focal central nervous system lesions due to stroke may result in symptoms and measurable evidence of unilateral disturbance of skin sympathetic function. Vasomotor asymmetries are probably due to lesions of vasomotor pathways descending uncrossed. Subjective coldness may be due to disturbed central processing.
Key Words: skin temperature stroke temperature sense vasomotor system
| Introduction |
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| Subjects and Methods |
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The control group consisted of 15 subjects, 5 women and 10 men aged 18 to 80 years (mean, 64±15 years), with a history of one transitory ischemic cerebral attack with a normal CT scan and no remaining symptoms of neurological or autonomic dysfunction. All were taking aspirin 75 mg/d, and 2 were taking ß-adrenergic blocking agents for hypertension.
The neurological evaluation was based on interviews and repeated clinical examinations. The patients were asked whether they had experienced a unilateral feeling of coldness or warmth or they had noticed asymmetry of perspiration, skin color, edema, "goose flesh," or eczema. Determination of the lesion location was based on clinical evaluation and CT scanning of the brain.
CT Scanning
The CT examination was performed with the scan plane parallel to
the canthomeatal plane, ie, a gantry tilt about -10° from Reid's
baseline using 5- to 10-mm slice thickness. Examinations were made on
day 1 or 2 in all cases and once more at least 4 weeks later in
patients with hemispheric lesions (except for five patients who refused
a second examination) to get a better delineation of the permanent
damage and its location and extent in relation to a
neuroanatomy atlas.12 The evaluation of the CT
scans was made by two experienced neuroradiologists without knowledge
of clinical data. With guidance from the atlas, 65 anatomic structures
were defined in the scans, and the lesions were related to these
structures and classified according to their vascular supply.
Laboratory Investigations
Temperature perception thresholds were recorded as the
thermoneutral zone using the Marstock thermotest method (Somedic) in
patients who experienced an asymmetrical temperature
sensation.13 Skin temperature was measured with an
electronic thermometer (Exacon) and skin evaporation with an
evaporimeter (Servomed AB). Measurements were taken bilaterally on the
plantar side of the big toes, the dorsum of the feet, pretibially,
subcostally on the belly, at the elbows between the lateral epicondyle
and the biceps tendon, in the palms, on the palmar side of the third
finger, and on the forehead, always in the same order. Skin blood flow
was monitored continuously and bilaterally on the plantar side of the
big toes with laser-Doppler flowmeters (Periflux PF1a, Perimed).
Respiratory movements were monitored by a strain gauge attached to the
patient's chest with a rubber band. Laser-Doppler and respiratory
signals were recorded on an ink-jet recorder (Mingograph 800,
Siemens-Elema) and an eight-channel FM tape recorder (Sangamo Sabre
VI, Sangamo-Weston Schlumberger) and later transferred to a computer
(PDP-11/70, sampling frequency of 25 Hz). Three types of stimuli were
used to evoke vasomotor reflexes: a single deep breath, arousal (a
sudden loud noise), and mental stress (subtraction of 6, 7, or 17 from
1000) for 60 seconds. The stimuli were given in random order, three
times each, with at least 3 minutes between stimuli. The examinations
were made in a quiet room by the same investigator (H.N.), after the
subjects had rested in bed with clothes on and covered by two woolen
blankets for 1 hour. Room temperature was 21°C to 23°C. Morning
body temperature was normal in all patients.
Analysis
Vasomotor Reflex Responses
For determination of the strength of the vasomotor response, the
computer calculated for each stimulus the mean laser-Doppler signal
from the three repetitions for a period of 30 seconds before and 150
seconds after the start of the stimulus. The mean laser-Doppler
perfusion value during the 30 seconds before stimulation was defined as
the basal perfusion. The response was defined as the deviation from the
basal perfusion (see Fig 3
). For each subject, the difference between
the responses on the left and right sides was calculated as (left
response-right response)/([left basal perfusion+right basal
perfusion]x
).
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Responses to a deep breath and arousal were determined for the first 15
seconds, whereas the response to mental stress was determined for the
period of 15 to 75 seconds after the start. These analysis
periods were chosen because the vasoconstrictor responses after arousal
or a deep breath start after a few seconds and usually reach a maximum
within 15 seconds. The responses to emotional stress start more slowly
(usual duration over 60 seconds), and to avoid contamination with the
arousal response, the first 15 seconds were excluded. To examine the
symmetry of the time course of the responses, cross-correlation was
performed for a period of 30 seconds (deep breath and arousal) or 60
seconds (mental stress) after the start of the stimulus.
Cross-correlation indexes were calculated during successive
displacements in each direction of corresponding laser-Doppler
curves from the two sides. The correlation index value at zero time
displacement was chosen as a measure of the degree of symmetry (see Fig 3
).
Skin Evaporation and Skin Temperature
For each pair of measurement points, the difference in
evaporation and skin temperature, respectively, was determined between
the ipsilesional and contralesional sides. To obtain an overall value
of the degree of symmetry, the mean difference of all eight measuring
sites was calculated.
Statistics
To evaluate whether the overall side asymmetry of skin
temperature, evaporation, and blood flow, respectively, was significant
in different groups of patients, Wilcoxon's signed rank test of
matched pairs was used. To classify the individual patient as being
symmetrical or asymmetrical compared with the control subject, 95%
confidence limits were used. Because six parameters were
used in classification of the vasomotor response (strength and time
course of the responses to mental stress, deep breath, and arousal,
respectively), confidence limits of each of these were set to
±(100%-5/6%)=±99.2%. Spearman's rank order correlation test was
used to test correlation between blood flow response and skin
temperature.
| Results |
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Other autonomic symptoms reported included one patient with a brain stem infarct who noticed goose flesh on the contralesional side, which felt cold. Objectively, there was piloerection only on that side. One patient with a pontine lesion and one patient with a middle cerebral artery (MCA) infarct reported increased sweating in the contralesional hand during the first week. One patient with brain stem bleeding had initially profuse sweating in the ipsilesional side of the face. Two patients were troubled by a bluish discoloration in the contralesional extremity. Six patients had pain on the contralesional side, and three of them had a warm sensation; in addition, two had swelling in the paretic hand.
Location of the Lesion
Among the hemispheric stroke patients (n=26), there were five
centrally located bleedings, seven lacunar infarcts, and 12 medial and
two anterior cerebral artery infarcts. No correlation was found between
the size of the lesion in the CT scan and asymmetries in autonomic
function tests. Neither was there a difference with respect to
autonomic symptoms or measurements between hemorrhagic or
ischemic strokes.
Of the brain stem lesions (n=11), two were lateral pontine bleedings visible on CT (with corresponding symptoms) and nine were ischemic lesions with normal CT scans classified by unequivocal clinical findings as lateral medullary infarcts (n=6), lateral pontine infarcts (n=2), and combined lateral and medial medullary infarct (n=1).
Temperature Perception
Nineteen patients experienced subjective symptoms of temperature
asymmetry and hypalgesia (reduced or absent pinprick sensation) on the
contralesional side. In 11 of these patients, quantitative temperature
perception tests were made; eight patients could not be reliably tested
because of sensory neglect or aphasia. All patients tested had impaired
temperature perception in the hand of the contralesional side; of the
10 patients whose feet were examined, eight had impaired temperature
perception in the foot on the contralesional side (Fig 1
). The thermoneutral zone of the contralesional side
was significantly wider than that of the ipsilesional side
(P<.05).
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The thermoneutral zone (mean±SD) of the ipsilesional side in the patients was 3.4±1.8°C in the thenar area and 9.1±3.1°C on the dorsum of the feet. Corresponding values in the control group were 1.9±0.8°C (P<.01) and 6.8±2.1°C (P<.05), respectively. All six patients with central pain had hypalgesia, and the three of them who could cooperate in the thermotest had impaired temperature perception in the contralesional side.
Skin Temperature
Skin temperature was lower in the contralesional side of the whole
patient group (P<.002, n=36). The asymmetry was
statistically significant also in the subgroup of patients with
hemispheric stroke (P<.01; n=26) but not in the subgroup
with brain stem stroke (Table 1
).
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On an individual basis, seven of 35 patients (six hemispheric and one
brain stem lesion) had an abnormal skin temperature asymmetry due to a
lower skin temperature in the contralesional side (Fig 2
). Four of these patients had a subjective sensation of
coldness. No correlation was found between skin temperature and the
degree of temperature asymmetry.
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Sweating
Clinically, hyperhidrosis was noted only in one
patient (with a left-sided brain stem hemorrhage and sweating
in the right side of the face). In patients with hemispheric lesions,
the skin evaporation was lower, ie, there was a relative hypohidrosis
in the contralesional side compared with the ipsilesional side (mean
side difference, 2.0 g H2O/m2 skin per hour,
P<.02) (Table 1
); in contrast, there was a relative
hyperhidrosis of about the same magnitude (2.2 g
H2O/m2 skin per hour, P<.01) in the
contralesional side of patients with brain stem lesions (Table 1
). The
asymmetry was similar but more pronounced when measured only in hands
and feet instead of the whole body. The two patients who noticed an
initial increased sweating in the paretic hand had no side asymmetry
(clinically or objectively) at the time of investigation. On an
individual basis, eight of 35 patients (23%) had an abnormal asymmetry
of sweating. There was no correlation between side differences in
skin temperature and evaporation or between evaporation and subjective
sensation of temperature asymmetry (Fig 2
). Neither was any correlation
found between the degree of motor impairment and evaporation
asymmetry.
Skin Blood Flow
Resting Blood Flow
Measurements of skin blood flow were made in 15 control subjects
and 32 patients. The mean skin blood flow level at rest was lower in
the contralesional than in the ipsilesional side (P=.05).
The degree of asymmetry was similar but not significant in the
subgroups with hemispheric and brain stem stroke. No side difference
was present in control subjects.
Vasomotor Responses to Stimuli
The response pattern varied both between maneuvers and between
subjects. In control subjects, both a deep breath and arousal usually
led to short-lasting flow reductions (with a minimum flow within 10
seconds) followed by transient flow increases for 10 to 20 seconds.
Occasionally, however, the response was either a monophasic reduction
(n=1) or increase of flow (n=3). The response to mental stress, on the
other hand, was most commonly a sustained increase of blood flow
(sometimes preceded by a short vasoconstriction as after arousal),
which almost always outlasted the 60-second stress period (Figs 3
and 4
). In three subjects, the stress
response was a monophasic vasoconstriction. Mean skin temperature in
the contralesional toes was 29.7°C (range, 23.5°C to 34.5°C). No
correlation was found between skin temperature and blood flow
response.
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In 11 of 32 stroke patients (34%), the vasomotor responses were asymmetrical. In five patients, there were asymmetries in both the strength of the flow response and its time course; in two cases, only the time course was abnormal, and in four only the strength. All asymmetries in the strength of vasomotor responses, whether they were vasodilatations evoked by mental stress (n=3) or vasoconstrictions after a deep breath (n=4) or arousal (n=2), had weaker or absent responses for the ipsilesional side.
Relation to Clinical Symptoms
Of the 11 patients with asymmetrical responses, six had no or only
a discrete motor paresis, and three had moderate and two severe
hemiparesis. Ten had reduced pain and temperature sensibility,
suggesting disturbance of the spinothalamic pathways.
The proportion of asymmetrical vasomotor reflexes in patients
complaining of coldness in the contralesional extremity was
significantly higher (P<.001) than in patients without such
symptoms (Table 2
). No patient complaining of warm
sensation in a contralesional extremity had asymmetrical vasomotor
reflexes.
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The mean vasomotor response for the patients complaining of coldness was asymmetrical with respect to vasodilatation, which was significantly weaker in the ipsilesional side (P<.05).
Relation to the Site of the Lesion
Six of the 11 patients with asymmetrical vasomotor response had
hemispheric lesions (three lacunar and three MCA infarcts), and five
had lateral brain stem lesions with medial medullary extension in one
case. No significant asymmetries were seen except for the subgroup of
patients with MCA strokes (n=10), in whom the vasoconstriction response
to a deep breath was asymmetrical and weaker in the ipsilesional side
(P<.05).
| Discussion |
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In theory, the varying time between the acute stroke and the investigation may have affected the results. However, since examinations were made more than 6 days after the stroke, irritative (hyperexcitability) phenomena probably do not confound the picture. Furthermore, the results found in patients investigated before and after day 25 did not differ; therefore, it seems likely that the time factor is of minor importance. Transient ischemic attack patients were preferred to healthy subjects for control purposes to include persons with similar vascular status and risk factors as stroke patients. This should have minimized misinterpretation of changes in temperature and autonomic functions due to general manifestations of atherosclerosis as the result of clinically manifest central nervous system damage.
Vasomotor Dysfunction
Basal Blood Flow
Because of variations in epidermal and/or vascular microstructure,
resting cutaneous blood flow measured with the laser-Doppler
technique may differ markedly between sites located only a few
millimeters apart.14 Such random variations should not,
however, affect group comparisons, and we therefore conclude that our
finding of a lower basal blood flow in the contralesional side
represents a stroke-induced effect. The underlying mechanism is
unclear. Theoretically, increased cutaneous vasoconstrictor nerve
traffic in the contralesional side or decreased traffic in the opposite
side (or a corresponding contrary asymmetry of vasodilator nerve
traffic) would be possible explanations. The literature contains
conflicting reports on temperature and skin perfusion asymmetries in
cerebral lesions.5 6 7 8 9 10 11 Our finding of more pronounced
vasoconstriction in the contralesional side agrees with the most recent
of these reports,11 in which stroke patients complaining
of coldness in the paretic hand were found to have a reduced skin
temperature at rest and after cold stimuli, as well as a reduced blood
flow in the symptomatic hand.
Reflex Responses
Vasomotor reflex responses were asymmetrical in 34% of the
patients, and the asymmetries occurred both with brain stem and
hemispheric lesions. On the basis of the CT scan or the clinical
findings, all but one of the patients with hemispheric strokes who had
asymmetrical responses had lesions in the region of the posterior
branch of capsula interna and the posterolateral part of the thalamus.
The brain stem stroke patients with vasomotor reflex asymmetry all had
symptoms suggesting disorder of spinothalamic
pathways.
The close anatomic relationship between central skin vasomotor pathways and afferent temperature and pain pathways may explain the correlation between asymmetries of vasomotor reflexes and temperature perception: the lesion may have affected both structures. Alternatively the vasomotor asymmetry may be a reflex consequence of a lesion of afferent thermal pathways. In a physiological study, Cooper and Kerslake15 found that short-lasting heating of the legs induced reflex vasodilatation in the hands; in another report,6 it was concluded that a normal vasodilatation response required intact afferent and efferent fibers in structures above the brain stem level. Interruption of this reflex pathway may contribute to our finding of a correlation between disturbed sensibility and asymmetry of vasomotor responses.
Vasomotor responses that were asymmetrical in the strength of the response were always weaker in the ipsilesional side regardless of whether a vasoconstriction or a vasodilatation occurred. A possible explanation would be that excitatory nerve fibers involved in vasodilator and vasoconstrictor responses descend uncrossed. This would agree with results from previous studies suggesting that the majority of sympathetic hypothalamic projections to the spinal cord are ipsilateral.16 17 An alternative (or additive) mechanism could be that pathways with an inhibitory effect on vasomotor reflexes descend crossed. A loss of inhibitory influence would then lead to amplification of reflexes in the contralesional side.
Sudomotor Dysfunction
Clinical hyperhidrosis was present in only one
of our patients. This agrees with the results of Labar et
al,1 who observed that about 1% of a large group of
stroke patients sweated more on the paretic than the nonparetic side
during days 1 to 3. The same direction of asymmetry during the first
week after the stroke was found in patients with hemispheric stroke
studied by Korpelainen et al.3 Because cortical electrical
stimulation also results in contralateral perspiration,18
these asymmetries may in theory be irritative phenomena, not
present in our patients who had ipsilesional
hyperhidrosis when examined on day 6 or later. However,
this explanation does not agree with the results from the longitudinal
study of Korpelainen et al, who found that, although the magnitude of
the asymmetry in their study had decreased 1 month after the stroke,
the direction of asymmetry was still unchanged (and opposite to ours).
Our results are also different in that we found no correlation to the
degree of motor paresis in patients with hemispheric stroke. In
contrast to Korpelainen et al, we did not warm the patients, and we
also kept them in bed for 1 hour before taking measurements. This may
have affected the magnitude, but it is not probable that it would have
affected the direction of the asymmetry. The group of patients with
brain stem lesions who had contralesional hyperhidrosis
in our study had no or sparse motor impairment, suggesting that factors
other than motor deficit are of importance for the
hyperhidrosis. In a study of sympathetic skin
responses, Korpelainen et al4 found contralesional
increased sweat responses after brain stem lesions only and not after
hemispheric lesions, which is in accordance with our results. Previous
studies give evidence for dual central excitatory sudomotor pathways: a
crossed cortico-limbico-spinal tract18 and an uncrossed
hypothalamo-reticulo-spinal pathway.18 19 Hypothetically,
therefore, the asymmetry of evaporation after hemispheric lesions in
our study may be explained by lesions primarily affecting the crossing
cortico-limbico-spinal pathway, and the asymmetry after brain stem
lesion may be a result of lesions primarily affecting the
hypothalamo-reticulo-spinal thermoregulatory pathway.
Thermal Asymmetries
Skin Temperature
Skin temperature was about 0.4°C lower in the contralesional
side in patients with hemispheric lesions. The mean side difference in
the smaller group of patients with brain stem infarcts was similar but
did not reach statistical significance. The temperature asymmetry did
not correlate to the sensation of coldness, but that does not exclude a
correlation under other circumstances. Our patients were resting in bed
covered by blankets for 1 hour before measurements. This procedure was
adopted to achieve standardized measurement conditions, but it may have
reduced asymmetries. In support of this possibility, one patient
(without evidence of neuropathy or leg artery
stenosis) had skin temperature of 9°C to 10°C lower in the
paretic leg on several occasions when out of bed. In contrast, the
difference was only 1°C to 2°C when the patient was
immobilized under blankets in bed.
In theory, the lower skin temperature in the contralesional than in the ipsilesional side may be due to either increased evaporation or reduced blood flow in the contralesional side. Since our patients with hemispheric lesions had lower evaporation and cutaneous blood flow in the contralesional side, the lower temperature in that side was probably due to the reduced blood flow. This would also agree with Thiele and van Senden,20 who found that cutaneous vasoconstriction caused a lowering of skin temperature, which resulted in a decreased insensible perspiration.
Temperature Perception
Determination of temperature perception thresholds requires a high
degree of cooperation of the subject. Many stroke patients have
difficulty with the test because of impaired concentration, slow
reactions to stimuli, inattention to the paretic side, or sensory
dysphasia with difficulty in understanding instructions. Although
patients were excluded from the temperature perception test whenever
such symptoms were detected, widened thermoneutral zones in the
ipsilesional side were found. Since patients with pure central
hemispheric lesions also had widened thermoneutral zones in the
ipsilesional side, compliance of the patients is probably not the cause
of this result. An alternative explanation would be that some
spinothalamic pathways have bilateral thalamic
projections.21 The high prevalence of reduced
temperature perception in patients with coldness may be an
overestimation, since not all were tested. However, the pinprick
sensation test, which does not demand the same degree of cooperation
from the patient and therefore was studied in all patients, was also
reduced in all patients with coldness, which supports the thermotest
result. Our findings of impaired pinprick sensation and temperature
perception in the patients with pain in the paretic side agree with the
results of Boivie et al,22 who studied patients with
poststroke pain. However, our results also show that these findings are
not specific but may occur in patients without poststroke pain.
Sensation of Coldness on the Contralesional Side
Because skin temperature was lower on the contralesional side, the
sensation of coldness on this side may reflect an adequate perception
of the temperature asymmetry. In view of the markedly impaired
temperature perception on the contralesional side, this explanation
seems unlikely. However, it cannot be totally disregarded, since we
measured only the width of the thermoneutral zone; therefore, a
selective impairment of warmth perception (with preserved cold
perception) is difficult to exclude. The coldness probably is not due
to inactivity of the extremity, since more than 50% of patients with
that symptom had no or only a slight hemiparesis. A more likely
explanation for the sensation of coldness may be that it is caused by a
disturbed central processing. This would be compatible with the
correlation between hypalgesia, thermohypesthesia, and coldness in the
contralesional side and would be an explanation that is analogous to
that used to explain the occurrence of poststroke
pain.22
Conclusion
Symptoms suggestive of autonomic dysfunction on one side of the
body after stroke are common, and objective measurements demonstrate
the occurrence of sweat, temperature, and skin perfusion asymmetries.
The symptom of coldness on the contralesional side is related to skin
vasomotor reflex asymmetry and a lesion of spino-thalamo-cortical
pathways and may be due to a disturbed central processing.
| Acknowledgments |
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Received January 13, 1995; revision received April 24, 1995; accepted April 27, 1995.
| References |
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