Normative data of sympathetic skin response and RR interval variation in Turkish children

Sympathetic skin response (SSR) and RR interval variation (RRIV) are used commonly for the assessment of sympathetic and parasympathetic nervous system function, respectively. We determined the normal values of SSR and RRIV in 23 (14 females, nine males) Turkish children aged 5 to 14 (mean 9.86, SD 2.48) years. SSR was recorded on the hands and feet during the electrical stimulation of both median and posterior tibial nerves, respectively. Similar response was elicited on both feet during the stimulation of the right median nerve. RRIV testing was performed during rest on the supine position and deep inspiration at a frequency of 6 times/min. The SSR was elicited in all children. The mean SSR latencies recorded on the feet during the stimulation of median or posterior tibial nerve were significantly more prolonged than those recorded at the hands (P < 0.001). There was no significant difference between the mean latencies of SSR recorded at the ipsilateral and contralateral palms or soles. The mean latencies recorded at the sole during stimulation of the median nerve were not significantly different compared to those that recorded at the sole during the posterior tibial nerve (P > 0.05). The SSR amplitudes were not assessed because of great variability and rapid habituation. The mean RRIV (46.54+/-11.29%) during deep breathing was significantly increased as compared to that (35.90+/-10.63%) during rest (P < 0.003). As a result, SSR and RRIV are preferred non-invasive tests for evaluation of autonomic nervous system in children. The SSR is useful and reliable if it is obtained in the optimum technical conditions. Further research is necessary to establish strict criteria for abnormality.     

Sympathetic skin response evoked by laser skin stimulation

The objective of this study was to evoke sympathetic skin responses (SSRs) in healthy subjects using laser stimulation and to compare these responses with those induced by conventional electrical stimuli. Twenty healthy subjects were investigated. SSRs were obtained using electrical and laser stimuli delivered to the wrist controlateral to the recording site. The sympathetic sudomotor conduction velocity (SSFCV) was measured in 8 subjects by simultaneously recording the SSR from the hand and the axilla. The latency (L) of the laser-induced SSR (ISSR) was significantly longer than that of the electrically-evoked SSR (eSSR) (mean ISSRL= 1.7 +/- 0.145 ms, mean eSSRL= 1.56 +/- 0.14 ms, p<0.05). The amplitude (A) of the ISSR was lower than the eSSR amplitude (mean ISSRA = 1.31 +/- 0.26 mV, mean eSSRA = 2.59 +/- 0.49 mV, p<0.05). No significant difference between the ISSR and eSSR was observed in either the SSFCV or the variability and reproducibility parameters. Our findings show that SSRs can easily be induced by laser stimuli and that this method shares the technical limitations of conventional eSSRs.     

Preserved sympathetic skin response at the distal phalanx in patients with carpal tunnel syndrome.

OBJECTIVE: To assess the viability of sympathetic sudomotor fibers in carpal tunnel syndrome (CTS). METHODS: We recorded sympathetic skin response (SSR) with a multichannel recording system. Forty-four patients with CTS (51 hands), 7 patients (7 hands) with asymptomatic median mononeuropathy at the wrist (MMW), and 20 normal subjects (20 hands) were studied. We classified the patients into 4 grades of increasing severity. RESULTS: In the hands of normal subjects, SSR was evoked easily at all recorded sites. SSR at the wrist in patients with asymptomatic MMW decreased in amplitude. SSR was markedly distorted at the wrist in severe grades of CTS. The SSR amplitude ratio (wrist/distal phalanx) decreased significantly with more severe grade (rh=-0.4; P<0.05), but the sensitivity was lower than that of other electrodiagnostic criteria. A patient with persistent allodynia at the wrist after surgery showed the slight recovery of SSR amplitude ratio; the other two patients without allodynia showed substantial recovery of SSR amplitude ratio within 24 weeks after surgery. CONCLUSION: SSR amplitude ratio is a poor indicator of CTS diagnosis, but may be useful in assessing the viability of sympathetic sudomotor fibers and may assist in evaluating the response to surgery.     

Sympathetic skin response in carpal tunnel syndrome.

OBJECTIVES: Sudomotor efferent nerve fiber function was studied in carpal tunnel syndrome (CTS). METHODS: Bilateral median and ulnar sympathetic skin response (SSR) were recorded by sternal stimulation in 22 bilateral and 9 unilateral patients and compared with 21 healthy volunteers. RESULTS: There was no significant difference between median and ulnar nerve SSR latency, amplitude or area. The median nerve SSR was not different from that of the controls. The median-to-ulnar ratios of SSR parameters were not different in patients and controls. However, the median-to-ulnar ratios of SSR amplitude and area were lower than normal in 3 out of 7 patients with normal nerve conduction whereas this abnormality was found in only 4 out of 46 patients with abnormal nerve conduction. CONCLUSIONS: Normal SSR results, even in patients with complaints related to sudomotor sympathetic dysfunction, indicate that the SSR does not seem to be a sensitive diagnostic method in CTS.     

The significance of intact sympathetic skin responses in carpal tunnel syndrome

The current study aimed to investigate the impact of carpal tunnel syndrome (CTS) on sympathetic skin response (SSR) recorded from the median and ulnar territory. Thirty patients were studied and idiopathic CTS was documented in a total of 46 hands. These were classified, according to electrophysiological criteria, into two groups; a group of 31 hands with severe CTS and a group of 15 hands with mild/moderate CTS, and were compared with a group of 30 hands of age-matched controls. SSR was recorded simultaneously from the median and ulnar side of the palm following electrical stimulation at the wrist, in a mid-point between median and ulnar nerve. Latency, amplitude, habituation and the median-to-ulnar ratio were estimated. In all controls clear recordings of SSR were obtained. In the patient groups, absence of SSR was never observed either in mild/moderate or in the severe CTS hands. The mean SSR latency and amplitude values recorded from both the median and ulnar nerves did not significantly differ between mild/moderate or severe CTS hands and controls. Likewise, the median-to-ulnar ratio and habituation of SSR latencies and amplitudes did not significantly differ between groups. SSR does not seem to be a sensitive method for evidence of autonomic involvement in CTS, even in patients manifesting sudomotor or other autonomic symptoms. In the present setting, SSR appeared to be independent of somatic afferent function and the corresponding sensory action potentials.     

Characteristics of habituation of the sympathetic skin response to repeated electrical stimuli in man.

OBJECTIVES: To study the effect of repeating electrical peripheral nerve stimulation on latency, duration and amplitude of the sympathetic skin response (SSR). METHODS: SSRs were elicited in all limbs by median and peroneal nerves stimuli. In 10 subjects, 20 stimuli were applied at random time intervals (15-20 s). Another test was performed in 7 subjects using the same protocol, but switching the stimulation site every 5 or 10 stimuli without warning. RESULTS: The mean amplitude of right palmar response to right peroneal nerve stimulation decreased from 5.05+/-0.76 (SEM) mV at the first stimulus to 1.23+/-0.42 mV at the 20th stimulus (P<0.001). The latency did not change significantly (1473+/-82 to 1550+/-90 ms, P>0.1), while the duration increased (1872+/-356 to 3170+/-681 ms, P<0.001). Stimulation and recording at other sites showed similar trends. Changing the stimulation site failed to alter the adaptation process in terms of amplitude, latency or duration. CONCLUSIONS: Changes in amplitude and duration of the SSRs to repeated electrical stimuli can occur in presence of constant latency and appear to be independent of the source of sensory input. Peripheral sweat gland mechanisms may be involved in the loss of amplitude and increase in duration of the SSR during habituation.     

Sympathetic skin response in patients with reflex sympathetic dystrophy

The sympathetic skin response (SSR) originates from synchronized activation of the sweat glands as a response to a volley discharge in efferent sympathetic nerve fibres. The aim of the study was to verify the diagnostic value of SSR in patients with reflex sympathetic dystrophy (RSD). SSR was recorded in 20 normal subjects and in 24 patients with predominantly chronic RSD. In normal subjects inter- and intra-individually different mono-, bi- and triphasic potentials could be recorded without difference of the waveform from side to side. SSR abnormalities were found in 15 patients and correlated with the severity of the disease. In patients with slight dystrophies, SSR was predominantly normal. In intermediate dystrophies, mainly differences of the SSR waveform between sides could be recorded, indicating unilateral sudomotor dysfunction. In severe dystrophies abnormalities of SSR amplitude or latency were found, indicating more serious disturbance of sudomotor activity, possibly due to a lesion of sympathetic fibres. The SSR provides useful information on sudomotor dysfunction in patients with RSD. However, as there is no consensus in the literature for the clinical criteria to diagnose RSD, it is not yet possible to determine the final diagnostic value of SSR for the diagnoses of RSD.     

Hyperhidrosis in Parkinson's disease.

We studied the sudomotor skin response (SSR) in patients with Parkinson's disease with and without symptomatic hyperhidrosis. The study was carried out in 13 patients who complained of excessive sweating and in 37 patients who did not have excessive sweating. Patients were matched for age, sex, degree of impairment, duration of the disease, and number and severity of autonomic disturbances. Excessive sweating involved mainly the face, head, and trunk. The SSR was recorded from the palm of the hands to electrical stimulation of the median nerve at the wrist. We analyzed onset latency, peak to peak amplitude, and waveform. Patients with hyperhidrosis had more often absent responses (chi(2) = 5.292; P = 0.021), their responses were of lower mean amplitude (analysis of variance [ANOVA]; F[2,101] = 11.678; P < 0.001), and they had a reduced number of responses with a predominantly negative component (chi(2) = 8.493; P = 0.004) than patients who did not complain of sweating disturbances. Our results indicate that excessive sweating in Parkinson's disease concurs with decreased activation of sweat glands in the palms of the hands and suggests that axial hyperhidrosis could be a compensatory phenomenon for reduced sympathetic function in the extremities.     

Estimation of the conduction velocity of sympathetic sudomotor C fibres in healthy subjects: study of sympathetic skin reflex.

The aim of this study was to establish a simple method for estimating the conduction velocity (CV) of post-ganglionic sympathetic sudomotor C fibres (SSFCV) in the upper and lower limbs by simultaneously measuring the sympathetic skin reflex (SSR) in two distant sites. Fifty healthy volunteers were studied. SSRs were recorded with standard surface electrodes applied to both proximal (axilla and crural line) and distal sites for each limb (hand and foot). The CV of the efferent branch of the SSR was calculated by dividing the difference in the latencies of the response from two recording sites by the distance between the sites (axilla-hand for upper limb; crural line-foot for lower limb). Day-to-day reproducibility and intra-individual variability of the SSFCV were calculated. For the upper limbs, the SSFCV in the axilla-hand tract was 2.0+/-0.3 m/sec (range 1.6-2.4 m/sec). For the lower limb, the SSFCV in the crural line-foot tract was 1.4+/-0.4 m/sec (range 1.2-1.6 m/sec). Mean intra-individual variability of the SSFCV for the upper and lower limbs was 0.11 and 0.09, respectively. The coefficient of variation of the SSFCV for the upper and lower limbs was 5.1% and 5.4%, respectively. Our data show that this simple and non-invasive method can reliably be used to measure the CV of the sympathetic sudomotor fibres, in suitable temperature conditions, and may be useful when investigating the physiological functions of peripheral nerves in patients with peripheral neuropathies.     

The sympathetic skin response in carpal tunnel syndrome

The sympathetic skin response (SSR) is an evoked change in electrical skin potential and is an index of the function of sympathetic pathways. We studied the SSR evoked by electrical stimulation of the median nerve and recording from the contralateral hands in 30 patients with carpal tunnel syndrome (CTS) without clinical autonomic signs and compared the results to the SSR in 30 normal controls. The SSR was absent in the affected hands in seven (23%) patients. In the other carpal tunnel syndrome patients (77%), a significant reduction in the SSR area was seen in the records from the affected hands. Subclinical sympathetic nerve fibre involvement occurs in the affected median nerves in CTS.     

Sympathetic skin response in idiopathic and diabetic carpal tunnel syndrome

BACKGROUND: In carpal tunnel syndrome (CTS), certain changes were expected in sympathetic skin response (SSR) because median nerve carries postganglionic unmyelinated fibres. PURPOSE: To investigate the median and ulnar SSR in idiopathic and diabetic CTS without autonomic dysfunction in hands and to find possible relations with electrophysiological features of these diseases. PATIENTS AND METHODS: SSRs were elicited by electrical stimulation on the supraorbital nerve and recorded from the median and ulnar territories in the hand from 20 diabetic patients with only CTS (29 hands), 24 idiopathic CTS patients (42 hands) and 13 normal subjects (26 hands). Hands with ulnar neuropathy at the wrist without symptoms and normal hands of unilateral CTS were excluded. In addition to classical parameters and comparative methods, SSR waveform changes and percentile method was used in finding abnormality. RESULTS: Median SSRs had significant delayed latency compared to ulnar latency in both CTS patients but this was not important clinically (1.38/1.37 s for idiopatic CTS; 1.43/1.36 s for diabetic CTS). Median and ulnar SSR amplitude, area, median/ulnar latency difference, amplitude and area ratio were compared and only median/ulnar latency difference and median/ulnar latency ratio were found different between the three groups. Four idiopathic CTS hands were outside of the limits or absent (9.5%). SSR waveforms were significantly different from normal subjects in CTS patients. P type SSR replaced M type in idiopathic CTS and N type in diabetic CTS. CONCLUSIONS: Findings regarding SSR parameters suggest that unmyelinated C fibers were affected in CTS. These values were not useful because they were too small. Data on SSR were not normally distributed and the percentile method seems to be more convenient for finding any abnormality in clinical practice. Also, SSR waveform analysis could give us valuable data and should add to the SSR examination parameters.     

Habituation of sympathetic sudomotor and vasomotor skin responses: neural and non-neural components in healthy subjects.

OBJECTIVE: Sympathetic skin response (SSR) and skin vasomotor response (SVR) habituation was thought to be induced by neural mechanisms. Here, we investigate the hypothesis that non-neural mechanisms could also be involved. METHODS: We recorded sympathetic skin nerve activity (SSNA) from median nerve by microneurography and the corresponding SSR and SVR in 16 healthy subjects. Superficial electrical stimulation of the opposite median nerve was used to induce arousal responses. RESULTS: Throughout stimulation, SSNA, SSR and SVR amplitude showed a significant reduction. During the first ten stimuli, SSNA showed a marked decrease highly correlated to SSR and SVR changes. During the subsequent 20 stimuli SSNA did not change whereas SSR and SVR significantly decreased. SVR was significantly influenced by skin temperature changes. CONCLUSIONS: Both neural and non-neural mechanisms are involved in SSR and SVR habituation. The neural mechanisms were predominant during the first part of stimulation whereas non-neural mechanisms prevailed during the last part of stimulation. SIGNIFICANCE: During repeated arousal stimuli SSR and SVR amplitude changes did not reflect the strength of the corresponding sympathetic nerve traffic and must be interpreted with caution.     

Sympathetic skin responses in hemiplegic patients with and without complex regional pain syndrome

BACKGROUND AND AIMS: To investigate whether there were changes in the sympathetic skin responses (SSR) in the limbs with complex regional pain syndrome (CRPS) type I in hemiplegic patients. SETTING: A physical medicine and rehabilitation center in Turkey. MATERIALS AND METHODS: Sympathetic skin responses were evaluated in 69 stroke patients (41 with CRPS and 28 without CRPS) and 20 healthy volunteers. SSR were recorded on the paretic and healthy hands after stimulation of the ipsilateral median nerve. Patients' ages ranged from 33 to 77 years, with a mean of 60.0+/-12.9 years. RESULTS: The SSR were obtained in all patients with CRPS, whereas SSR was absent in 9 of 28 patients with hemiplegia who did not have CRPS after stimulation of the plegic side and the difference was statistically significant (P=0.023). SSR amplitudes were increased at the hemiplegic limbs in patients affected by CRPS compared to individuals unaffected; this group difference was statistically significant (P=0.014). The mean amplitude of the SSR in the advanced stage of CRPS was greater than lower stage and the difference was statistically significant (P=0.035). CONCLUSION: Our results suggest that SSR can be obtained in stroke patients with CRPS even in the early stages of CRPS. SSR acquirability and amplitude increase as the stage of the disease advances. As an electrophysiologic technique, SSR may be used in the evaluation of the sympathetic function in hemiplegic patients and also in the diagnosis of CRPS and in monitoring of its treatment.     

Sympathetic skin response in idiopathic and diabetic carpal tunnel syndrome

BackgroundIn carpal tunnel syndrome (CTS), certain changes were expected in sympathetic skin response (SSR) because median nerve carries postganglionic unmyelinated fibres.PurposeTo investigate the median and ulnar SSR in idiopathic and diabetic CTS without autonomic dysfunction in hands and to find possible relations with electrophysiological features of these diseases.Patients and methodsSSRs were elicited by electrical stimulation on the supraorbital nerve and recorded from the median and ulnar territories in the hand from 20 diabetic patients with only CTS (29 hands), 24 idiopathic CTS patients (42 hands) and 13 normal subjects (26 hands). Hands with ulnar neuropathy at the wrist without symptoms and normal hands of unilateral CTS were excluded. In addition to classical parameters and comparative methods, SSR waveform changes and percentile method was used in finding abnormality.ResultsMedian SSRs had significant delayed latency compared to ulnar latency in both CTS patients but this was not important clinically (1.38/1.37 s for idiopatic CTS; 1.43/1.36 s for diabetic CTS). Median and ulnar SSR amplitude, area, median/ulnar latency difference, amplitude and area ratio were compared and only median/ulnar latency difference and median/ulnar latency ratio were found different between the three groups. Four idiopathic CTS hands were outside of the limits or absent (9.5%). SSR waveforms were significantly different from normal subjects in CTS patients. P type SSR replaced M type in idiopathic CTS and N type in diabetic CTS.ConclusionsFindings regarding SSR parameters suggest that unmyelinated C fibers were affected in CTS. These values were not useful because they were too small. Data on SSR were not normally distributed and the percentile method seems to be more convenient for finding any abnormality in clinical practice. Also, SSR waveform analysis could give us valuable data and should add to the SSR examination parameters.     

Comparison of the sympathetic skin response and continuous wave Doppler sonography of the radial artery

The value of neurophysiological tests of the autonomic nerve system is limited. One of the clinically most commonly applied test is the skin sudomotor response, frequently referred to as 'sympathetic skin response' (SSR). However, the SSR is a more qualitative than quantitative evaluation technique. Continuous wave (cw) Doppler sonography of the radial artery may be an alternative quantitative approach. We studied 41 age matched volunteers (23 female, 18 male; 16-82 years (mean age 53 years)). The stimulus was a loud and unexpected acoustic signal, alternatively a cough. SSR evaluation included the latency of onset, the duration and the amplitude of the response. Doppler evaluation also included flow velocity and resistance index (RI) changes with adequate stimulation. SSRs were observed in 36 volunteers (88%), Doppler responses in 35 (85%). The latency between stimulus and response onset was 1.35 s with SSR and 1.52 s with ultrasound (n.s.). The mean SSR amplitude was 1.3 mV, systolic velocities decreased by 20% and diastolic velocities by 124% (flow reversal). RI increased from 0.85 to 1.25 with no correlation between SSR amplitude and flow velocity changes. SSR and cw Doppler are complementary methods. Doppler sonography offers an additional approach of autonomic nerve evaluation.     

Sympathetic skin response in psoriasis and vitiligo.

The sympathetic skin response (SSR) which is considered to be one of the indexes of peripheral autonomic nerve function, especially evaluates sudomotor function of unmyelinated sympathetic fibers. This noninvasive technique has been studied in various neurological disorders particularly in peripheral neuropathies and also in some dermatological disorders associated with nervous system involvement. However, literature lacks sufficient data regarding SSR in immunologically mediated skin disorders. We enrolled patients with vitiligo and psoriasis to determine the possible effects of these disorders on SSR. Examination of SSR was performed in 30 patients with psoriasis and 15 patients with vitiligo as well as in 23 healthy volunteers as controls. Right and left median nerves were stimulated successively and responses were recorded from the palms simultaneously. SSR could be obtained from every subject. The groups were not statistically different for the values of the latency, the amplitude, and the area under the negative component of SSR. Our results indicated that vitiligo and psoriasis did not have any significant effects on SSR.     

Sympathetic skin responses of the hand in normal subjects: shorter latency at distal phalanx

We studied the conduction of the sympathetic skin response (SSR) in the hands of 35 normal subjects by simultaneous recording at five sites. The mean latency of the SSR in all subjects increased from the wrist (W) to the middle phalanx (M), but the SSR latency at the distal phalanx (D) was shorter than that at the middle phalanx. The mean conduction time and conduction velocity from W to M was 197.5 ms and 0.87 m/s, respectively, and that from W to D was 48.8 ms and 2.34 m/s, respectively. For evaluation of the cause of the shorter latency at D, digital nerve blocking was performed in two subjects. The blocking of the volar digital nerves at the proximal phalanx abolished SSR at M and D. It was postulated that the initiation or conduction of sudomotor nerve impulse to the distal phalanx would be facilitated compared with those to the other proximal sites in the hand. The SSR conduction time between W and M may be a means of detecting alteration of sympathetic sudomotor nerve activity.     

Sympathetic skin response following thermal, electrical, acoustic, and inspiratory gasp stimulation in familial dysautonomia patients and healthy persons

To determine whether sympathetic skin response (SSR) testing evaluates afferent small or efferent sympathetic nerve fiber dysfunction, we studied SSR in patients with familial dysautonomia (FD) in whom both afferent small and efferent sympathetic fibers are largely reduced. We analyzed whether the response pattern to a combination of stimuli specific for large or small fiber activation allows differentiation between afferent and efferent small fiber dysfunction. In 52 volunteers and 13 FD patients, SSR was studied at palms and soles after warm, cold and heat as well as electrical, acoustic, and inspiratory gasp stimulation. In addition, thermal thresholds were assessed at four body sites using a Thermotest device (Somedic; Stockholm, Sweden). In volunteers, any stimulus induced reproducible SSRs. Only cold failed to evoke SSR in two volunteers. In all FD patients, electrical SSR was present, but amplitudes were reduced. Five patients had no acoustic SSR, four had no inspiratory SSR. Thermal SSR was absent in 10 patients with abnormal thermal perception and present in one patient with preserved thermal sensation. In two patients, thermal SSR was present only when skin areas with preserved temperature perception were stimulated. In patients with FD, preserved electrical SSR demonstrated the overall integrity of the SSR reflex but amplitude reduction suggested impaired sudomotor activation. SSR responses were dependent on the perception of the stimulus. In the presence of preserved electrical SSR, absent thermal SSR reflects afferent small fiber dysfunction. A combination of SSR stimulus types allows differentiation between afferent small or efferent sympathetic nerve fiber dysfunction.     

Occurrence of the spinal reflex due to skin pressure in sudomotor and cutaneous vasoconstrictor nerve system of humans

The effects of skin pressure applied to one side of the waist on sudomotor and vasoconstrictor nerve activity were compared with the effects on sweating and cutaneous blood flow in humans. The sweat rate and cutaneous blood flow were measured on left and right dorsal feet. Skin sympathetic nerve activity (SSNA) was recorded by microneurography from a microelectrode inserted in left and right peroneal nerves. Skin pressure was applied in a supine position to the area over the left or right anterior superior iliac spine under warm (T(a): 30-36 degrees C) and cool (T(a): 19-23 degrees C) conditions. Sudomotor and vasoconstrictor bursts were identified for quantitative analysis. The skin pressure increased the contralateral/ipsilateral ratio of the sweat rate. It also increased the contralateral/ipsilateral ratio of the cutaneous blood flow and the contralateral/ipsilateral ratio of the sudomotor burst amplitude. However, skin pressure did not induce any significant changes in the contralateral/ipsilateral ratio of the vasoconstrictor burst amplitude. The results indicate that an asymmetrical reflex effect of skin pressure on vasoconstrictor nerve activity was absent, suggesting that, whereas the ipsilateral suppression of sweating elicited by skin pressure was mediated by the sudomotor nerve system, the ipsilateral suppression of cutaneous blood flow was not mediated by the vasoconstrictor nerve system. Thus, the occurrence of the spinal reflex due to skin pressure is not uniform between the sudomotor and the vasoconstrictor nerve systems, which represent different organizations at the level of spinal cord.     

Recovery of sympathetic skin responses after digit-to-digit replantation and toe-to-digit transplantation in humans

Sympathetic skin response was utilized to study recovery of sudomotor function in 8 patients who had digit-to-digit replantation and 9 patients who had toe-to-digit transplantation. Sympathetic skin responses evoked by median nerve stimulation or magnetic stimulation of the neck were recorded from the tip of the replanted digits or transplanted toes. The contralateral normal fingers served as controls. The mean intervals between surgery and study were 33 and 37 months, respectively, for digit replantation and toe transplantation. In normal subjects, the sympathetic skin responses recorded from the fingertip were abolished by local anesthesia or cooling of the finger, while those recorded from the palm were not affected. Ischemia of the finger only transiently affected the digit sympathetic skin responses. These data indicate that the digit responses were locally generated and mediated by unmyelinated fibers. After digit replantation, the palm and digit sympathetic skin responses were not different between replanted and normal sides. After toe transplantation, palm sympathetic skin responses were normal, but digit ones had prolonged latency and reduced amplitude. The present findings suggest that recovery of sympathetic sudomotor activity can be nearly complete in digit replantation but less satisfactory in toe transplanatation.