Vet Res Commun DOI 10.1007/s11259-014-9608-z
ORIGINAL ARTICLE
Electrical stimulation of lumbar spinal nerve roots in dogs Erkut Turan & Cengiz Unsal & Mehmet Utkan Oren & Omer Gurkan Dilek & Ismail Gokce Yildirim & Murat Sarierler
Accepted: 3 June 2014 # Springer Science+Business Media Dordrecht 2014
Abstract The aim of this study was to test the applicability of electrical stimulation of lumbar spinal nerve roots and obtain normative electrical root stimulation (ERS) data for L7 nerve root and sciatic nerve in dogs. For that purpose ERS and sciatic nerve stimulations were performed consecutively, in totally 40 healthy dogs. ERS was applied in the L7/S1 intervertebral space via monopolar needle electrodes. Muscle responses were recorded from the gastrocnemius muscles on the left and right hind limbs. Sciatic nerve stimulation was performed at the greater trochanter level on the left hind limb, with records obtained from the left gastrocnemius muscle. Mean root latencies of the left and right side were 5.22± 0.49 ms and 5.29±0.53 ms, respectively. There was no significant difference in root latency between the right and left sides. The mean terminal latency was 3.82±0.46 ms. The proximal motor nerve conduction velocity of the sciatic nerve was 63.15±3.43 m/s. The results of this study show that ERS provides objective data about the integrity of lumbar spinal nerve roots by evaluating the entire population of motor fibres E. Turan (*) : M. U. Oren : I. G. Yildirim Department of Anatomy Faculty of Veterinary Medicine, Adnan Menderes University, PK: 17, Işikli-Aydin, 09016, Turkey e-mail: [email protected] E. Turan e-mail: [email protected] C. Unsal Department of Physiology, Faculty of Veterinary Medicine, Adnan Menderes University, Aydin, Turkey O. G. Dilek Department of Anatomy, Faculty of Veterinary Medicine, Mehmet Akif Ersoy University, Burdur, Turkey M. Sarierler Department of Surgery, Faculty of Veterinary Medicine, Adnan Menderes University, Aydin, Turkey
and total length of the motor axon in dogs. ERS can be considered a useful diagnostic method for confirmation of diagnoses of lumbosacral diseases. Keywords Electrical root simulation . Nerve conduction velocity . Sciatic nerve and Dog
Introduction The location and severity of neuromuscular disorders can be evaluated objectively using a variety of electroneuromyographic (ENMG) techniques (Oh 1993; Cuddon 2002; Lorenz et al. 2011). These techniques reveal objective informations about functional statuses of muscles, neuromuscular junction, ventral nerve root, alpha motor neuron and nerve conduction (Cuddon 2002; Oh 1993). Electrical root stimulation (ERS) is one of ENMG techniques, used for the diagnosis of lumbar/cervical spinal nerve root pathologies in humans (Macdonell et al. 1992; Ertekin et al. 1994a; Menkes et al. 1998). The spinal nerves and their proximal parts can be investigated with ERS (Evans et al. 1990; Macdonell et al. 1992; Ertekin et al. 1994a; Ertekin et al. 1994b; Menkes et al. 1998; Uludag et al. 2000; Fisher 2002; Tataroglu et al. 2007). It involves the electrical stimulation of a spinal nerve at the root level and recording of muscle responses (M-responses) using surface and concentric needle electrodes simultaneously. ERS has been shown to be superior to conventional nerve conduction studies (NCSs) for the diagnosis of lumbosacral spine and nerve root pathologies in humans (Ertekin et al. 1994b; Menkes et al. 1998; Fisher 2002; Zileli et al. 2002). In dogs, pathologies encountered in the lumbar region include degenerative lumbosacral stenosis, discospondylitis, neoplasia, subluxation, spondylitis deformans (Chrisman 1982; Kornegay 1986; Tennent–Brown 2007), and trauma
Vet Res Commun
(Jacobson and Schrader 1987). Traumatic injury of the proximal sciatic nerve (Chrisman 1982; Lorenz et al. 2011) and entrapment neuropathy of the intrapelvic portion of this nerve have also been reported (Sorjonen et al. 1990; Ocal and Sarierler 2007). These conditions can show similar clinical signs, rendering differential diagnosis difficult (Sjöström 2003; Sharp and Wheeler 2005). Imaging studies and electrophysiological tests have been suggested to the functional evaluation and more accurate diagnosis of these pathologies (Sharp and Wheeler 2005). For instance electrophysiologic bulbocavernosus reflex test reveals neurologic abnormalities before the appearance of neurological signs and symptoms in the compression of cauda equina (Kim et al. 1994). This ENMG technique is recommended to the functional integrity of the sacral spinal cord as a routine and highly accurate diagnostic method in dogs (Turan and Bolukbasi 2006; Turan et al. 2008). No study to date has reported the establishment of normative reference data for lumbar ERS in the field of veterinary medicine. Thus, the aims of the present study were to test the applicability of the ERS technique and to obtain normative data for ERS of the L7 nerve root and sciatic nerve in healthy dogs.
Materials and Methods
lateral recumbent position. Left hind limb length was measured between the greater trochanter and tips of third toe using a tape measure. The areas in which surface electrodes would be placed were shaved and cleaned with 10 % ethanol. The lumbosacral region was also cleaned with 10 % ethanol and 10 % povidone iodine (Batticon®, Adeka). Skin temperature was recorded from the left hind limb using the surface probe. ENMG studies were conducted with a four-channel Nicolet Viking Quest® device (VIASYS). The ERS method for humans (Macdonell et al. 1992; Ertekin et al. 1994b; Uludag et al. 2000) was modified for dogs in this study. Two stimulation and recording procedures were performed consecutively for each dog. The first was ERS to obtain root latency between nerve root and target muscle. The second was sciatic nerve stimulation to obtain terminal latency and to calculate proximal motor nerve conduction velocity (MNCV). Proper placement of electrodes was determined by preliminary studies in both procedures. Stimulation of the seventh lumbar nerve root was preferred because it is the thickest branch to the sciatic nerve. Monopolar needle electrodes were used for stimulation. The active electrode (50 mm; 902-DMG50-TP®, Teca) was inserted into the L7/S1 intervertebral space from the caudal side of the spinous process of the L7 vertebra. The reference electrode (37 mm; 902-DMF37-TP®, Teca) was inserted subcutaneously 2 to 3 cm cranial to the active electrode in the mid-plane (Fig. 1).
Animals This study was conducted in the Electroneuromyography Laboratory of the Faculty of Veterinary Medicine with the approval of the Animal Ethics Committee of Adnan Menderes University. ENMG studies were performed in 40 healthy dogs (22 males and 18 females; eight German shepherds, eight golden retrievers, seven Rottweilers, four Doberman pinschers, four Labrador retrievers, four pit bull terriers, three cane corsos, one American bulldog, and one boxer) with signed consent of the owners. The ages of dogs ranged from 8 to 72 (34.55±20.30) months. The dogs were selected based on the absence of neurological deficit on neurological examination, normal routine haematological findings and normal serum calcium level. Full blood counts were performed (Abacus Junior Vet 5®, Diatron) and serum calcium levels were measured using spectrophotometric test kits (A2060®, Archem Diagnostics Ind. Ltd.). ENMG studies Following the subcutaneous administration of 2 % atropine sulphate (30 to 50 μg/kg; Atropine®, Vetaş), general anaesthesia was induced with the intramuscular administration of xylazine (1.1 mg/kg; Rompun®, Bayer) and ketamine (22 mg/kg; Ketanes®, Alke). Each dog was placed in the right
Fig. 1 a: Schematic illustration of electrodes placement in ERS. Stimulating active (SA), stimulating reference (SR), recording active (RA), recording reference (RR), concentric (C) and surface grounding (G) electrodes. b: Detailed illustration of placement of active stimulating electrode in the median section of L7/S1 intervertebral space. Stimulating active electrode (SA), laminar level of lumbosacral spine (LL), Lumbar 7 vertebra (L7v), Sacrum (S), Lumbar 7 root (L7r)
Vet Res Commun
Surface bipolar electrodes (6030-3-TP®, Medelec) and concentric needle electrodes (37 mm; S53156®, Medelec) were used synchronously to record muscle responses of gastrocnemius muscles of the left and right extremities. The active electrodes were placed on the mid-portions of muscle bellies and the reference electrode was placed on the muscle tendons. Concentric electrodes were placed immediately adjacent to the active electrodes, and surface grounding electrodes were placed between the stimulating and recording electrodes (Fig. 1). The distances between active stimulation and recording electrodes were measured by pelvimetry (Martin ET 73®, Elcon) on the right and left sides. Due to simultaneous recording, the same or similar latency was expected for responses from the superficial and concentric needle electrodes. Amplitudes and latencies were evaluated bilaterally using M-responses obtained from the surface electrodes. Latencies were recorded at the initial deflection from baseline and amplitudes were measured as peak-to-peak (Fig. 2). Equipment settings were: amplification filters, 10 Hz to 10 kHz; sweep speed, 5 ms; and duration, 0.5 ms. The gain was adjusted according to the magnitude of M-responses in all procedures. Stimulation was applied manually as rectangular electric pulses at random intervals, and stimulus intensity was increased in a stepwise manner [34 to 125 (71.32 ± 22.88) V] until a supramaximal M-response was obtained. To position the active stimulus electrode near the L7 root, it was necessary to advance it gently while electric pulses (30 to 40 V) were delivered at the random interval. When the tip of the active electrode approached the lamina level of
Fig. 2 Electromyogram recordings; obtained with surface (A1) and concentric needle (A2) electrodes from the right gastrocnemius muscle; surface (A3) and concentric needle (A4) electrodes from the left gastrocnemius muscle in ERS. Latency and amplitude of wave on recording paper are shown the vertical and horizontal lines
lumbar spine, the segmental motor contractions from both legs were observed. After minor adjustments to the position of the electrode until an M-response with the highest amplitude and stable configuration was obtained from gastrocnemius muscles. After proper placement, at least five robust and reproducible M-responses were recorded. Sciatic nerve stimulation was applied between ischial spine and the medial side of the greater trochanter on left hind limb. The active electrode (50 mm; 902-DMG50TP®, Teca) was inserted close to the sciatic nerve on the medial side of the greater trochanter and the reference electrode (37 mm; 902-DMF37-TP®, Teca) was inserted subcutaneously 2 to 3 cm proximal to the active electrode. The locations of bipolar surface recording electrodes were the same in both procedures (Fig. 3). The distances between the active stimulus and surface recording electrodes were measured by pelvimetry. The settings were: amplification filters, 2 Hz to 10 kHz; sweep speed, 5 ms; and duration, 0.5 ms. Stimulus intensity was increased until a supramaximal response was obtained [23 to 109 (59.70± 20.79) V]. To ensure reproducibility, stimulation was applied until five robust M-responses were recorded.
Fig. 3 Schematic illustration of electrodes placement in sciatic nerve stimulation. Stimulating active (SA), stimulating reference (SR), recording active (RA), recording reference (RR) and surface grounding electrode (G)
Vet Res Commun
Data analysis Proximal MNCVs between the root and sciatic nerve stimulation points were calculated using formula of “Proximal MNCV (m/s): distance between the root and sciatic nerve stimulation points/(root latency - terminal latency)”. The differences in root latency between sides were also calculated. Data were analysed using SPSS 19.0 software. Means and standard deviations (SDs) of all data were calculated, as well as 95 % confidence intervals (CIs) of latency and proximal MNCV data and ranges of amplitudes. The normality of distributions of body weights, hind limb lengths, latencies and proximal MNCV was examined using the one-sample Kolmogorov–Smirnov test. Needle and surface electrode latencies of the left and right hind limbs were compared using the paired t-test. Pearson correlation coefficients and 2-tailed significance tests were used to estimate the correlation between the surface electrode latencies of right and left limbs and ages. Statistical significance was set at p
ORIGINAL ARTICLE
Electrical stimulation of lumbar spinal nerve roots in dogs Erkut Turan & Cengiz Unsal & Mehmet Utkan Oren & Omer Gurkan Dilek & Ismail Gokce Yildirim & Murat Sarierler
Accepted: 3 June 2014 # Springer Science+Business Media Dordrecht 2014
Abstract The aim of this study was to test the applicability of electrical stimulation of lumbar spinal nerve roots and obtain normative electrical root stimulation (ERS) data for L7 nerve root and sciatic nerve in dogs. For that purpose ERS and sciatic nerve stimulations were performed consecutively, in totally 40 healthy dogs. ERS was applied in the L7/S1 intervertebral space via monopolar needle electrodes. Muscle responses were recorded from the gastrocnemius muscles on the left and right hind limbs. Sciatic nerve stimulation was performed at the greater trochanter level on the left hind limb, with records obtained from the left gastrocnemius muscle. Mean root latencies of the left and right side were 5.22± 0.49 ms and 5.29±0.53 ms, respectively. There was no significant difference in root latency between the right and left sides. The mean terminal latency was 3.82±0.46 ms. The proximal motor nerve conduction velocity of the sciatic nerve was 63.15±3.43 m/s. The results of this study show that ERS provides objective data about the integrity of lumbar spinal nerve roots by evaluating the entire population of motor fibres E. Turan (*) : M. U. Oren : I. G. Yildirim Department of Anatomy Faculty of Veterinary Medicine, Adnan Menderes University, PK: 17, Işikli-Aydin, 09016, Turkey e-mail: [email protected] E. Turan e-mail: [email protected] C. Unsal Department of Physiology, Faculty of Veterinary Medicine, Adnan Menderes University, Aydin, Turkey O. G. Dilek Department of Anatomy, Faculty of Veterinary Medicine, Mehmet Akif Ersoy University, Burdur, Turkey M. Sarierler Department of Surgery, Faculty of Veterinary Medicine, Adnan Menderes University, Aydin, Turkey
and total length of the motor axon in dogs. ERS can be considered a useful diagnostic method for confirmation of diagnoses of lumbosacral diseases. Keywords Electrical root simulation . Nerve conduction velocity . Sciatic nerve and Dog
Introduction The location and severity of neuromuscular disorders can be evaluated objectively using a variety of electroneuromyographic (ENMG) techniques (Oh 1993; Cuddon 2002; Lorenz et al. 2011). These techniques reveal objective informations about functional statuses of muscles, neuromuscular junction, ventral nerve root, alpha motor neuron and nerve conduction (Cuddon 2002; Oh 1993). Electrical root stimulation (ERS) is one of ENMG techniques, used for the diagnosis of lumbar/cervical spinal nerve root pathologies in humans (Macdonell et al. 1992; Ertekin et al. 1994a; Menkes et al. 1998). The spinal nerves and their proximal parts can be investigated with ERS (Evans et al. 1990; Macdonell et al. 1992; Ertekin et al. 1994a; Ertekin et al. 1994b; Menkes et al. 1998; Uludag et al. 2000; Fisher 2002; Tataroglu et al. 2007). It involves the electrical stimulation of a spinal nerve at the root level and recording of muscle responses (M-responses) using surface and concentric needle electrodes simultaneously. ERS has been shown to be superior to conventional nerve conduction studies (NCSs) for the diagnosis of lumbosacral spine and nerve root pathologies in humans (Ertekin et al. 1994b; Menkes et al. 1998; Fisher 2002; Zileli et al. 2002). In dogs, pathologies encountered in the lumbar region include degenerative lumbosacral stenosis, discospondylitis, neoplasia, subluxation, spondylitis deformans (Chrisman 1982; Kornegay 1986; Tennent–Brown 2007), and trauma
Vet Res Commun
(Jacobson and Schrader 1987). Traumatic injury of the proximal sciatic nerve (Chrisman 1982; Lorenz et al. 2011) and entrapment neuropathy of the intrapelvic portion of this nerve have also been reported (Sorjonen et al. 1990; Ocal and Sarierler 2007). These conditions can show similar clinical signs, rendering differential diagnosis difficult (Sjöström 2003; Sharp and Wheeler 2005). Imaging studies and electrophysiological tests have been suggested to the functional evaluation and more accurate diagnosis of these pathologies (Sharp and Wheeler 2005). For instance electrophysiologic bulbocavernosus reflex test reveals neurologic abnormalities before the appearance of neurological signs and symptoms in the compression of cauda equina (Kim et al. 1994). This ENMG technique is recommended to the functional integrity of the sacral spinal cord as a routine and highly accurate diagnostic method in dogs (Turan and Bolukbasi 2006; Turan et al. 2008). No study to date has reported the establishment of normative reference data for lumbar ERS in the field of veterinary medicine. Thus, the aims of the present study were to test the applicability of the ERS technique and to obtain normative data for ERS of the L7 nerve root and sciatic nerve in healthy dogs.
Materials and Methods
lateral recumbent position. Left hind limb length was measured between the greater trochanter and tips of third toe using a tape measure. The areas in which surface electrodes would be placed were shaved and cleaned with 10 % ethanol. The lumbosacral region was also cleaned with 10 % ethanol and 10 % povidone iodine (Batticon®, Adeka). Skin temperature was recorded from the left hind limb using the surface probe. ENMG studies were conducted with a four-channel Nicolet Viking Quest® device (VIASYS). The ERS method for humans (Macdonell et al. 1992; Ertekin et al. 1994b; Uludag et al. 2000) was modified for dogs in this study. Two stimulation and recording procedures were performed consecutively for each dog. The first was ERS to obtain root latency between nerve root and target muscle. The second was sciatic nerve stimulation to obtain terminal latency and to calculate proximal motor nerve conduction velocity (MNCV). Proper placement of electrodes was determined by preliminary studies in both procedures. Stimulation of the seventh lumbar nerve root was preferred because it is the thickest branch to the sciatic nerve. Monopolar needle electrodes were used for stimulation. The active electrode (50 mm; 902-DMG50-TP®, Teca) was inserted into the L7/S1 intervertebral space from the caudal side of the spinous process of the L7 vertebra. The reference electrode (37 mm; 902-DMF37-TP®, Teca) was inserted subcutaneously 2 to 3 cm cranial to the active electrode in the mid-plane (Fig. 1).
Animals This study was conducted in the Electroneuromyography Laboratory of the Faculty of Veterinary Medicine with the approval of the Animal Ethics Committee of Adnan Menderes University. ENMG studies were performed in 40 healthy dogs (22 males and 18 females; eight German shepherds, eight golden retrievers, seven Rottweilers, four Doberman pinschers, four Labrador retrievers, four pit bull terriers, three cane corsos, one American bulldog, and one boxer) with signed consent of the owners. The ages of dogs ranged from 8 to 72 (34.55±20.30) months. The dogs were selected based on the absence of neurological deficit on neurological examination, normal routine haematological findings and normal serum calcium level. Full blood counts were performed (Abacus Junior Vet 5®, Diatron) and serum calcium levels were measured using spectrophotometric test kits (A2060®, Archem Diagnostics Ind. Ltd.). ENMG studies Following the subcutaneous administration of 2 % atropine sulphate (30 to 50 μg/kg; Atropine®, Vetaş), general anaesthesia was induced with the intramuscular administration of xylazine (1.1 mg/kg; Rompun®, Bayer) and ketamine (22 mg/kg; Ketanes®, Alke). Each dog was placed in the right
Fig. 1 a: Schematic illustration of electrodes placement in ERS. Stimulating active (SA), stimulating reference (SR), recording active (RA), recording reference (RR), concentric (C) and surface grounding (G) electrodes. b: Detailed illustration of placement of active stimulating electrode in the median section of L7/S1 intervertebral space. Stimulating active electrode (SA), laminar level of lumbosacral spine (LL), Lumbar 7 vertebra (L7v), Sacrum (S), Lumbar 7 root (L7r)
Vet Res Commun
Surface bipolar electrodes (6030-3-TP®, Medelec) and concentric needle electrodes (37 mm; S53156®, Medelec) were used synchronously to record muscle responses of gastrocnemius muscles of the left and right extremities. The active electrodes were placed on the mid-portions of muscle bellies and the reference electrode was placed on the muscle tendons. Concentric electrodes were placed immediately adjacent to the active electrodes, and surface grounding electrodes were placed between the stimulating and recording electrodes (Fig. 1). The distances between active stimulation and recording electrodes were measured by pelvimetry (Martin ET 73®, Elcon) on the right and left sides. Due to simultaneous recording, the same or similar latency was expected for responses from the superficial and concentric needle electrodes. Amplitudes and latencies were evaluated bilaterally using M-responses obtained from the surface electrodes. Latencies were recorded at the initial deflection from baseline and amplitudes were measured as peak-to-peak (Fig. 2). Equipment settings were: amplification filters, 10 Hz to 10 kHz; sweep speed, 5 ms; and duration, 0.5 ms. The gain was adjusted according to the magnitude of M-responses in all procedures. Stimulation was applied manually as rectangular electric pulses at random intervals, and stimulus intensity was increased in a stepwise manner [34 to 125 (71.32 ± 22.88) V] until a supramaximal M-response was obtained. To position the active stimulus electrode near the L7 root, it was necessary to advance it gently while electric pulses (30 to 40 V) were delivered at the random interval. When the tip of the active electrode approached the lamina level of
Fig. 2 Electromyogram recordings; obtained with surface (A1) and concentric needle (A2) electrodes from the right gastrocnemius muscle; surface (A3) and concentric needle (A4) electrodes from the left gastrocnemius muscle in ERS. Latency and amplitude of wave on recording paper are shown the vertical and horizontal lines
lumbar spine, the segmental motor contractions from both legs were observed. After minor adjustments to the position of the electrode until an M-response with the highest amplitude and stable configuration was obtained from gastrocnemius muscles. After proper placement, at least five robust and reproducible M-responses were recorded. Sciatic nerve stimulation was applied between ischial spine and the medial side of the greater trochanter on left hind limb. The active electrode (50 mm; 902-DMG50TP®, Teca) was inserted close to the sciatic nerve on the medial side of the greater trochanter and the reference electrode (37 mm; 902-DMF37-TP®, Teca) was inserted subcutaneously 2 to 3 cm proximal to the active electrode. The locations of bipolar surface recording electrodes were the same in both procedures (Fig. 3). The distances between the active stimulus and surface recording electrodes were measured by pelvimetry. The settings were: amplification filters, 2 Hz to 10 kHz; sweep speed, 5 ms; and duration, 0.5 ms. Stimulus intensity was increased until a supramaximal response was obtained [23 to 109 (59.70± 20.79) V]. To ensure reproducibility, stimulation was applied until five robust M-responses were recorded.
Fig. 3 Schematic illustration of electrodes placement in sciatic nerve stimulation. Stimulating active (SA), stimulating reference (SR), recording active (RA), recording reference (RR) and surface grounding electrode (G)
Vet Res Commun
Data analysis Proximal MNCVs between the root and sciatic nerve stimulation points were calculated using formula of “Proximal MNCV (m/s): distance between the root and sciatic nerve stimulation points/(root latency - terminal latency)”. The differences in root latency between sides were also calculated. Data were analysed using SPSS 19.0 software. Means and standard deviations (SDs) of all data were calculated, as well as 95 % confidence intervals (CIs) of latency and proximal MNCV data and ranges of amplitudes. The normality of distributions of body weights, hind limb lengths, latencies and proximal MNCV was examined using the one-sample Kolmogorov–Smirnov test. Needle and surface electrode latencies of the left and right hind limbs were compared using the paired t-test. Pearson correlation coefficients and 2-tailed significance tests were used to estimate the correlation between the surface electrode latencies of right and left limbs and ages. Statistical significance was set at p
