L5 Dermatome Research Articles

O8 Contact heat evoked potentials of lower extremities – A feasibility study

Objectives Contact heat evoked potentials (CHEPs) present a non-invasive technique to study thermo-nociceptive pathways. Eliciting CHEPs from the lower extremities, particularly from the dorsum of the foot, has so far been considered to be rather difficult and poorly reproducible. Therefore, the goal of this study was to assess the feasibility and reliability of CHEPS from lower extremities in healthy subjects. Methods Two stimulation protocols, i.e., normal and increased baseline protocol, were applied in 32 healthy subjects. The study protocol consisted of unilateral assessments of warm detection- and heat pain thresholds, followed by CHEPs recordings. Stimulation sites were the L2, L5, as well as the S2 dermatomes. CHEPs were recorded as vertex potentials from the Cz electrode. Results Contact heat stimulation of the L2, L5 and S2 dermatome reliably elicited cortical N2P2 components. While the amount of evoked potentials for the dermatomes L2 and S2 was close to 100% in both stimulation protocols, the proportion of EPs in the most distal dermatome, i.e., L5, was improved by 13% with the increased baseline stimulation protocol. The increased baseline stimulation protocol led to decreased N2 latencies, increased N2P2 amplitudes and improved test-retest reliability. Discussion/Conclusion CHEPs recordings from the lower extremities could be reliably recorded from the lower extremities and were markedly improved by using an increased baseline protocol.The establishment of normative data will be meaningful for improving the applicability of CHEPS for the diagnosis of small-fibre neuropathies. Significance CHEPs might be used as non-invasive assessment for small-fibre neuropathies.

Percutaneous endoscopic lumbar discectomy: minimally invasive technique for multiple episodes of lumbar disc herniation

BackgroundsAlthough open lumbar discectomy is a gold standard surgical technique for lumbar disc herniation (LDH), surgery-induced tissue injury may actually become a source of postsurgical pain. Percutaneous endoscopic lumbar discectomy (PELD) is introduced as a minimal invasive spinal technique for LDH. The PELD has gained popularity and shown successful results. The authors report the clinical usefulness of the PELD technique in two patients with the serial multilevel LDHs.Case presentationsA 32-year-old man suffered from radicular pain at the L5 dermatome due to the down migrated soft LDH at the L4–5 level. The PELD was performed to remove the ruptured fragments, yielding a complete decompression of the L5 nerve root. Four years later, he visited the clinic because of right leg radiating pain along the S1 dermatome. An MRI scan revealed the LDH at the L5-S1 level. The PELD with foraminoplasty was also performed successfully at the L5-S1 level. Two months after the second PELD, he visited the clinic again because of severe pain along the left L4 dermatome; consequently, the PELD was also performed at the L3–4 level without any complications. A 34-year-old man presented with radiating pain in the back and both legs at the L5 dermatome. The MR images show a disc extrusion at the L4–5. The patient underwent the PELD at the L4–5 via the left approach. After the PELD, the back and leg pain both improved. One year later, the patient suffered from severe pain in the back and the left anterior thigh. The MR images show a left paramedian LDH at the L2–3. After the PELD was performed at the L2–3, the pain was relieved. The final MR images show no signs of any aggravated degeneration of the intervertebral discs or the facet joints at all of the treated levels.ConclusionWhen multiple episodes of LDH occur in a patient’s life span, PELD could be considered as an alternative good technique to treat LDH in each step by preserving normal anatomic structures.

Reduced laser-evoked potential habituation detects abnormal central pain processing in painful radiculopathy patients.

Repetitive painful laser stimuli lead to physiological laser-evoked potential (LEP) habituation, measurable by a decrement of the N2/P2 amplitude. The time course of LEP-habituation is reduced in the capsaicin model for peripheral and central sensitization and in patients with migraine and fibromyalgia. In the present investigation, we aimed to assess the time course of LEP-habituation in a neuropathic pain syndrome, i.e. painful radiculopathy. At the side of radiating pain, four blocks of 25 painful laser stimuli each were applied to the ventral thigh at the L3 dermatome in 27 patients with painful radiculopathy. Inclusion criteria were (1) at least one neurological finding of radiculopathy, (2) low back pain with radiation into the foot and (3) a positive one-sided compression of the L5 and/or S1 root in the MRI. The time course of LEP-habituation was compared to 20 healthy height and age matched controls. Signs of peripheral (heat hyperalgesia) and central sensitization (dynamic mechanical allodynia and hyperalgesia) at the affected L5 or S1 dermatome were assessed with quantitative sensory testing. Painful radiculopathy patients showed decreased LEP-habituation compared to controls. Patients with signs of central sensitization showed a more prominent LEP-habituation decrease within the radiculopathy patient group. Laser-evoked potential habituation is reduced in painful radiculopathy patients, which indicates an abnormal central pain processing. Central sensitization seems to be a major contributor to abnormal LEP habituation. The LEP habituation paradigm might be useful as a clinical tool to assess central pain processing alterations in nociceptive and neuropathic pain conditions. Abnormal central pain processing in neuropathic pain conditions may be revealed with the laser-evoked potential habituation paradigm. In painful radiculopathy patients, LEP-habituation is reduced compared to healthy controls.

Sensory thresholds at different sites of the foot: a valuable reference for neurologic examinations

Study design:Prospective healthy volunteer study for sensory thresholds.Objectives:The aim of this study was to test sensory thresholds at different sites of the foot to provide a reference for diagnosis and neurologic classification.Setting:A university hospital for the research and clinical practice of rehabilitation.Methods:Thirty healthy volunteers were recruited, and quantitative sensory testing was performed on three sites of the foot (medial malleolus (for the L4 dermatome), dorsum of the foot at the third metatarsal phalangeal joint (for the L5 dermatome) and lateral heel (for the S1 dermatome)). First, cold sense, warm sense, cold pain and hot pain were tested. Second, a monofilament tactility test was performed. Finally, a physical examination for sensation was performed.Results:All of the thresholds for the medial malleolus were significantly different from those for the dorsum of the foot at the third metatarsal phalangeal joint and lateral heel, whereas no significant difference existed between the values for the dorsum of the foot at the third metatarsal phalangeal joint and lateral heel.Conclusion:The sensory threshold of the human medial malleolus may be significantly different from those of adjacent sites of the foot. Thus, the results obtained from physical examination of sensory thresholds of the medial malleolus should be used modestly as a reference, but should not be used for diagnostic or classification purposes.

Clinical presentation of a dorsal epidural arachnoid cyst after an epidural anaesthesia

Abstract Background Arachnoid cysts are dural diverticula with liquid content similar to cerebrospinal fluid, with 1% occurring in the spinal cord. They locate mainly in the dorsal region of the thoracic spine, and are unusual causes of spinal cord compression. Clinical case The case is presented of a previously healthy 15-year-old boy, with a 20-month history of spastic paraparesis that started apparently after epidural block for ankle osteosynthesis. There was decreased sensitivity and strength of the pelvic limbs and gradually presented with anaesthesia from T12 to L4 dermatomes, L5 and S1 bilateral hypoaesthesia and 4+/5 bilateral strength, in the L2 root and 2+/5 in L3, L4, L5, S1, hyperreflexia, Babinski and clonus, but with no alteration in the sacral reflexes. In the magnetic resonance it was diagnosed as an extradural arachnoid cyst from T6 to T9. The patient underwent a T6 to T10 laminotomy, cyst resection, dural defect suture, and laminoplasty. One year after surgery, the patient had recovered sensitivity, improvement of muscle strength up to 4+/5 in L2 to S1, and normal reflexes. Conclusions After the anaesthetic procedure, increased pressure and volume changes within the cyst could cause compression of the spinal cord, leading to symptoms. Despite being a long-term compression, the patient showed noticeable improvement.

Intradural Intramedullary Primary Spinal Melanocytoma: A Rare Case Report

Spinal melanocytomas are rare pigmented tumors of the central nervous system commonly affecting females in their fifth decades. It has been reported in various locations with intradural intramedullary being the rarest. Patients can present with varied symptomatology from mild backache to frank myelopathy. Here we report a case of 34-year-old man with no medical comorbidities with vague backache associated with numbness of anterior aspect of right thigh for 1 year aggravated by activities and relieved by rest. His neurologic examination revealed normal power and sensation in both lower limbs except for decreased temperature sensation in right L2 dermatome. MRI of dorsolumbar spine revealed a well-defined lesion that was hyperintense in T1- and hypointense in T2-weighted image at D11–12 region with uniform bright enhancement in gadolinium-enhanced T1 image. The patient underwent laminectomy of D11 and D12, and an en bloc excision was done. Diagnosis of primary intradural intramedullary melanocytoma was made from histopathologic examination. Spinal melanocytomas should be considered as a differential diagnosis for intradural space-occupying lesions. MRI remains the investigation of choice for diagnosis, but histopathologic examination is required to confirm and differentiate from other pigmented tumors and malignant melanomas. Total surgical excision of the tumor remains the standard treatment with radiotherapy reserved for cases of incomplete excision and recurrences.

Parameters of dermatomal somatosensory evoked potentials in normal conditions and patients with clinical symptoms of low back pain

Introduction. Dermatomal somatosensory evoked potentials (DSEP) are used to assess the function of afferent pathway following electrical stimulation of the skin around selected dermatomes of single spinal roots. Aim. The aim of the study was to characterize the parameters of DSEP latencies for assessment of L5 and S1 nerve root transmission in healthy people taking into account the important diagnostic difference between the right and left side and the impact of height, age and sex on values of DSEP latencies. Material and methods. DSEP tests were performed in the control group of 30 healthy volunteers and in the patients with low back pain radiating to one of the lower extremities for comparison. Disc‑root conflict was confirmed in MRI studies. Clinical examination included assessment of muscles strength innervated from the L5 and S1 roots and the sensory perception from L5 and S1 dermatomes. In all patients straight leg raising (SLR) and Schober's tests have been performed. To assess the severity of pain, the visual analogue scale (VAS) was used. The clinical and neurophysiological evaluation of patients was performed before and after 4 weeks of the physiotherapeutic exercises selected for this study. Results. Results indicated statistically significant relationship between the DSEP N33, P40, N50 components latencies and the height. The gender and age did not affect DSEP latencies. Values of DSEP latencies in the first and second periods of observations were normal and no sensory and motor disturbances have been observed in patients. DSEP test showed the high conformity with the results of clinical studies. Conclusions. DSEP diagnostic determines well the subjective sensation changes in patients suffering from low back pain. Kinesiotherapy treatment of patients with low back pain without neurological deficits seems to be the appropriate therapeutic method.

Epiduroscopic Laser Neural Decompression for Removal of L2-3 Disc Herniation in a Patient with Symptoms Suggestive of L5 Nerve Root Involvement.

Dear Editor, Epiduroscopy has previously been used for epidural adhesiolysis [1,2]. Recently, epiduroscopy with laser ablation has also been used for low back and radicular pain due to disc herniation, spinal stenosis, and failed low back surgery syndrome [3,4]. Epiduroscopic laser neural decompression (ELND) has become a useful tool for diagnostic purposes as well as the treatment for low back pain and/or radicular pain. With this technique (ELND), it is possible to remove disc fragments and adhesion bands, to confirm the epidural and nerve root pathology, to irrigate the epidural space, and to administer specific drugs close to the sites of pathology, all during one intervention. We wish to report a patient with symptoms of low back and radicular pain referable to the L5 dermatome but originating from a herniated disc at the L2–3 spinal segment, which was detected and promptly relieved by ELND. A 51-year-old woman sought treatment for her low back pain and radicular pain presenting in the right L5 dermatome. Her symptoms had abruptly commenced after playing golf. She was treated with medications …

Foraminal lumbar root schwannoma

A 55-year-old man with a past medical history of livingdonor renal transplant 10 years ago presented with chronic right radicular pain along the course of the right L5 nerve for several months duration. In his neurologic examination, he had sensorial disturbance along the right L5 dermatome. Plain radiographs of the lumbar spine showed enlargement of the right neural foramen without bone destruction (Fig. 1). Magnetic resonance imaging revealed a soft tissue mass in the right L4–L5 neural foramen causing neural foraminal widening and bone remodeling. The mass was heterogeneously hyperintense on T2-weighted image, hypointense to intervertebral disk on T1-weighted image, and showed intense homogeneous enhancement on postcontrast image (Figs. 2 and 3). The transplanted kidney was also seen on the right iliac fossa. The tumor was totally removed through a right L5 laminectomy and right-sided foraminotomy with instrumentation (Fig. 4). Histopathologic diagnosis was benign schwannoma. The patient was discharged without any motor deficit.

Effect of Mckenzie Method with tens on Lumbar Radiculopathy-A Randomized Controlled Trial

Background: Lumbar radiculopathy is a disease of the spinal nerve root generally accompanied by radicular pain in dermatomal distribution and/or neurologic symptoms. The previous studies were focusing on finding the disability and pain caused due to Lumbar Radiculopathy. This study is focusing on the disability, pain, range of motion of the spine and SLR. The objective of the study is to evaluate the effectiveness of Mckenzie method with TENS on reducing symptoms and disability of Lumbar radiculopathy.Methods: In the present prospective study patients with Lumbar radicular pain due to disc herniation or prolapse at level L4, L5 & S1 were randomized into two groups – Group A and Group B. the study included 40 patients, with 20 in each group. The selection criteria was based on the following - with age group 22-55years, both sexes – male and female, with radicular pain in L4, L5 & S1 dermatomes, disabling leg pain for 6-12 weeks duration, evidence of disc herniation confirmed on MR imaging. The radicular pain was measured using the SLR test, pain was measured using the VAS scale of 0 – 100, disability was measured using the MODI and Lumbar Spine ROM was measured using the MMST. Group-A were treated with McKenzie methods with TENS and Group-B were treated with general exercisewith TENS.Results: This study showed that there was a significant reduction of pain on the VAS, improvement in SLR, lumbar spine range of motion using MMST and disability using MODI for both the groups. The statistical analysis found that experimental group showed earlier control of all the outcome measures when compared to controlled group at the end of the 6th week.Conclusion: After 6 weeks of Mckenzie method with TENS intervention for 30 minutes for 5 days in week the statistical analysis concluded that the experimental group had significantly faster rates of reducing the symptoms of lumbar radiculopathy and reducing the disability due to lumbar radiculopathy.

Repeat spinal anesthesia in cesarean section: A comparison between 10 mg and 12 mg doses of intrathecal hyperbaric (0.05%) bupivacaine repeated after failed spinal anesthesia: A prospective, parallel group study.

Background:Spinal anesthesia for cesarean section is not a 100% successful technique. At times, despite straightforward insertion and drug administration, intrathecal anesthesia for cesarean section fails to obtain any sensory or motor block. Very few studies and literature are available regarding repeat administration of spinal anesthesia and its drug dosage, especially after first spinal failure in cesarean section lower segment cesarean section (LSCS) due to fear of the excessive spread of drug. The aim of our study is to compare the outcome between two different doses of 0.5% hyperbaric bupivacaine repeated intrathecally after failed spinal.Materials and Methods:After taking informed consent and Ethical Committee approval this prospective, randomized single-blinded study was conducted in 100 parturients of American Society of Anesthesiologists I-II who were posted for elective LSCS and had Bromage score 0 and no sensory block even at L4 dermatome after 10 min of first spinal anesthesia; were included in the study. Group A (n = 50) patients received 2.4 ml and Group B (n = 50) patients received 2 ml of 0.5% hyperbaric bupivacaine respectively for administering repeat spinal anesthesia. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), oxygen saturation, respiratory rate and electrocardiogram were monitored both intra- and post-operatively and complications were recorded.Results:Incidence of high spinal, bradycardia, hypotension, respiratory complications, and nausea vomiting are significantly higher in Group A compared to Group B (P < 0.05). SBP, DBP, and HR were significantly low in Group A patients compared to Group B in the first 10 min (P < 0.05).Conclusion:Spinal anesthesia can be safely repeated in the cesarean section with 10 mg of 0.5% hyperbaric bupivacaine provided after first spinal anesthesia, the level of sensory block is below L4 and motor power in Bromage scale is 0.

Case report of lumbar intradural capillary hemangioma.

Background:Capillary hemangioma is a rare tumor in spinal intradural location. Despite the rarity, early recognition is important because of the risk of hemorrhage. This is a case report of a woman who had capillary hemangioma of cauda equina.Case Description:A 54 -year-old woman presented with a low backache, radiating to the left leg for 2 months. She had left extensor hallucis weakness, sensory impairment in left L5 dermatome, and mild tenderness in lower lumbar spine. Magnetic resonance imaging (MRI) LS spine showed L4/5 intradural tumor, completely occluding canal in myelogram, enhancing with contrast, s/o benign nerve sheath tumor. L4 laminectomy was done. Reddish tumor was seen originating from a single root. It was removed preserving the root. Postoperatively, she was relieved of symptoms. MRI showed no residue. Histopathology showed lobular proliferation of capillary-sized blood vessels and elongated spindle cells. Immunohistochemistry showed CD34 positivity in endothelial cell lining of blood vessel and smooth muscle actin positivity in blood vessel muscle cells. HPR-capillary hemangioma.Conclusion:Although rare, capillary hemangioma should be in the differential diagnosis of intradural tumors. It closely mimics nerve sheath tumor.

Neurologic findings caused by ossification of ligamentum flavum at the thoracolumbar junction

Objective: To evaluate neurologic findings caused by a single ossification of ligamentum fravum (OLF) and identify the level of the lumbar segment of spinal cord.Design: Retrospective study.Methods: Subjects were 28 patients with a single OLF at T10-11 level (15 patients), T11-12 (11), and T12-L1 (2). The tip of the conus medullaris was assessed using computed tomographic myelography or magnetic resonance imaging. Neurologic evaluations were performed for patellar tendon reflex (PTR), sensory disturbance, and motor weakness.Results: The tip of the conus medullaris was located at the L1 vertebral body level. At the T10-11 level, all patients showed hyperreflexia of PTR. Sensory disturbance was observed for L1 dermatome and weakness of the iliopsoas was noted. At the T11-12 level, 8 of 11 patients didn't show hyperreflexia of PTR. Sensory disturbance was observed for L5 dermatome and weakness of the tibialis anterior was noted. At the T12-L1 level, all patients showed normal reflex of PTR, sensory disturbance of L5 dermatome, and weakness of the tibialis anterior.Conclusion: With regard to the relationship between PTR and OLF level, all patients at the T10-11 level showed involvement of the L3 segment of spinal cord proximally. On the other hand, most patients at the T11-12 level showed involvement of the L4 segment of spinal cord distally. From all neurologic findings, we confirmed the presence of the L4 segment of spinal cord from the lower third of T11 vertebral body to the T11-12 intervertebral disc level.

A Child Develops Drop Foot after Spinal Anaesthesia.

To the Editor, Spinal anesthesia has been used with children since 1909 (1). In 1950, a study reported that a cooperative child is likely to be a good subject for spinal anesthesia in cases where premedication may be inadequate (2). A nine-year-old girl weighing 20 kgs and with a height of 126 cm was diagnosed with acute appendicitis. An emergency operation was planned. Her medical history was normal except for a productive cough and runny nose over the previous three days. In the preoperative physical examination, rales in the lungs, extensive tenderness and distension in the abdomen were found. Thirty minutes before the operation, midazolam 0.05 mg/kg was given for premedication. A non-traumatic lumbar puncture was performed using a 26 G (Atraucan, 50 mm Braun Melsungen AG, Germany) pediatric spinal needle in the sitting position. At first at-tempt a clear cerebrospinal fluid flowed out, then 0.2 mg/kg of heavy bupivacaine was applied into the subarachnoid space between the third and fourth lumbar vertebrae. Sensorial block dermatome was checked using a pinprick test. When the level reached T8, the operation was started. The patient was hemodynamically stable during the operation and was in the recovery room for 30 minutes. In the sixth postoperative hour, she developed weakness in her left ankle, with muscle strength loss in the dorsiflexion (1/5), eversion (1/5), plantar flexion (3/5), toe dorsiflexion (1/5), and plantar flexion (3/5). Accompanying sensory deficit in the dorsum and anterolateral tibial part of the left leg (L5 and S1 dermatomes) was observed. Lumbar magnetic resonance imaging and computed tomography revealed normal findings. Postoperative 1st and 20th day electromyography showed no pathologic findings. A course of 25 mg/kg ga bapentin three times a day and vitamin B complex twice a day were prescribed. Physical therapy, including passive stretching, range of motion, balance, and strengthening exercises were performed. For the left anterior tibialmuscle, electrical stimulation was applied daily for 15 minutes. In neurological examination, improvement in muscle deficit was observed. Muscle strength was 4/5 in all of the muscles involved. Discharged with a home-based treatment program, she was able to walk without support on the 70th day. Although publications about complications of spinal anesthesia in children exist (3), there are few reports indicating safe and effective usage of spinal anesthesia (4,5). Transient neurological damage usually develops without pain or paresthesia during the lumbar puncture, as in our case. In differential diagnosis of neurological damage after spinal anesthesia, possible diagnosis of epidural hematoma, epidural abscess, anterior spinal artery syndrome, adhesivear-achnoiditis, caudaequina syndrome should be excluded. We excluded all these diagnoses with the help of a physical examination and MRI. Since the patient was in a supine position and had no history of any intramuscular injection, neurologic damage due to malpositioning or intramuscular injection were also excluded. In case of complications, a multidisciplinary approach is necessary for prompt and correct diagnosis, as well as to initiate the most appropriate mode of therapy for optimal results in the shortest time.

A new method for spike extraction using velocity selective recording demonstrated with physiological ENG in Rat

BackgroundThis paper describes a series of experiments designed to verify a new method of electroneurogram (ENG) recording that enables the rate of neural firing within prescribed bands of propagation velocity to be determined in real time. Velocity selective recording (VSR) has been proposed as a solution to the problem of increasing the information available from an implantable neural interface (typically with electrodes in circumferential nerve cuffs) and has been successful in transforming compound action potentials into the velocity domain. New methodThe new method extends VSR to naturally-evoked (physiological) ENG in which the rate of neural firing at particular velocities is required in addition to a knowledge of the velocities present in the recording. ResultsThe experiments, carried out in rats required individual spikes to be distinct and non-overlapping, which could be achieved by a microchannel or small-bore cuff. In these experiments, strands of rat nerve were laid on ten hook electrodes in oil to demonstrate the principle. Comparison with existing methodThe new method generates a detailed overview of the firing rates of neurons based on their conduction velocity and direction of propagation. In addition it allows real time working in contrast to existing spike sorting methods using statistical pattern processing techniques. ConclusionsResults show that by isolating neural activity based purely on conduction velocity it was possible to determine the onset of direct cutaneous stimulation of the L5 dermatome.

Injectate spread following ultrasound-guided lateral to medial approach for dual transversus abdominis plane blocks.

Bilateral dual transversus abdominis plane (BD-TAP) injections were devised to cover the T7-8 and L1 dermatomes, which are usually spared with classical and mid-axillary TAP injections. The purpose of this study was to delineate the vertical and lateral extent of injectate spread following a lateral to medial approach for TAP injections in embalmed cadavers. Ultrasound-guided subcostal and lateral TAP injections were performed on nine embalmed cadavers using 30 ml of 0.5% methylcellulose (20 ml for subcostal and 10 ml for lateral injections) with a 12-cm Tuohy needle in the first six cadavers (nine hemi-abdomens). Vertical extent and the medial to lateral extent of the dye spread were recorded after dissections of the abdominal wall. In a pilot of three cadavers not receiving TAP injections, anatomical impediments to proximal injectate spread were explored separately. The vertical spread of injectate was T7-L1 (n = 2/9), T8-L1 (n = 5/9) and T9-L1 (n = 2/9). None of the TAP injections extended beyond the mid-axillary line. No anatomical impediments for the flow of injectate to the T7 or T8 intercostal nerves were found at the level of the interdigitations of the transversus abdominis muscle and diaphragm. A lateral to medial approach for TAP injection resulted in spread of the injectate ranging from T7/8-L1 dermatomes in the majority of the hemi-abdomens. Subcostal and lateral TAP injections do not cover the lateral cutaneous branches of the segmental nerves.

Transversus abdominis plane block as sole anaesthetic technique for inguinal hernia repair in two patients having complex medical conditions

Sir, Transversus abdominis plane (TAP) block has been used as a sole anaesthetic technique for the patients with multiple co-morbidities presenting for emergency laparotomy.[1,2] We share our experience of using TAP block for the surgical anaesthesia in two patients scheduled for inguinal hernioplasty who had associated complex medical conditions. First patient was a 52-year-old male, known case of congenitally corrected transposition of great arteries (CCTGA) associated with severe pulmonary stenosis and a pressure gradient of 64 mm Hg, large non-restrictive ventricular septal defect (VSD) and right ventricular (i.e., physiologic left ventricle) dysfunction. He was stable on treatment with tablet torsemide. Second case was a 54-year-old male known case of Takayasu's arteritis (TA) and hypertension on treatment with tablet metoprolol and losartan. The patient had the history of claudication and weakness of left upper limb. The peripheral pulses in left upper limb were feeble and blood pressure (B.P) was lower compared to right upper limb (112/70 mm Hg vs. 172/73 mm Hg). For surgery, ultrasound guided (USG) TAP block was administered in both cases using in-plane posterior approach with 20 ml of 0.5% bupivacaine and 10 ml of 2% lignocaine. For visceral analgesia, the TAP block was supplemented with infusions of dexmedetomidine at the loading dose of 1 μg/kg over 10 min followed by 0.5-0.6 μg/kg/min infusion and fentanyl at 75-100 μg/h, respectively, in the first and the second case. In the first patient, T10 -L1 dermatomes were blocked whereas in second patient L1 was spared; only T10 -T12 blockade was achieved as checked by pin prick. The incision line was infiltrated with 2% lignocaine in the second case before surgery. The anaesthetic monitoring in both cases included continuous electrocardiogram, continuous invasive B.P monitoring, pulse oximetry, and temperature. The intraoperative vital parameters were stable and surgery was completed uneventfully in both cases. CCTGA is an uncommon congenital cardiac anomaly characterized by TGA along with the inversion of both ventricles and thus there is both atrio-ventricular and ventriculo-great vessel discordance. The anaesthetic haemodynamic goals in these cases are to maintain systemic vascular resistance (SVR) to avoid right to left shunt by VSD and to preserve myocardial contractility.[3] TA involves a focal stenotic process in the aorta and proximal segment of its main branches. In our second case, though angiography was not done, based on the history of claudication and findings of feeble pulses and decreased B.P. in left arm compared to right is suggestive of stenotic area to be in the arch of aorta. These patients may not tolerate the sudden fall in SVR as they have compromised regional circulation and hence similar to the first patient our intraoperative haemodynamic goal was to maintain SVR. We decided to use USG TAP block in both cases as being an abdominal field, it holds the promising advantage of maintaining the haemodynamics of patients, which are altered in general or neuraxial anaesthesia and additionally provides an excellent postoperative analgesia for 24-48 h. We chose dexmedetomidine infusion in the first patient as it has the combination of analgesic, sedative, and anxiolytic properties with the preservation of respiratory functions. There are 3 main issues which need consideration while using TAP block as a sole anaesthetic modality for surgery. First, TAP block covers only the somatic component of surgical pain; for visceral pain analgesia has to be supplemented with other analgesic agents hence it cannot be a sole anaesthetic technique. Second, the extent of dermatomal block provided by TAP block is uncertain. Both pinprick using blunt needle and cold disinfectant swabs can be used to assess dermatomal extent of sensory blockade. Lee et al.[3] reported that posterior approach produced a median sensory block of three dermatomal segments, the most cephalad being T10. We found the L1 dermatome to be spared in the second case despite using 30 ml of drug for block. Since the incision for inguinal hernia repair lies over T12 -L1 segments, additional infiltration of local anaesthetics (L.A) was required before surgery. Niraj et al.[4] also observed that posterior approach TAP block usually spares L1 segment. Another disadvantage of TAP block is potential to produce L.A. toxicity since large volumes of L.A. are used. There are case reports[5] of cardiac arrests due to L.A. systemic toxicity following TAP block. Therefore the volume of drug used should be carefully determined and the patient should be observed for at least 45 min after TAP block institution during intraoperative and postoperative period. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Pain-related evoked potential in healthy adults.

ObjectiveTo investigate the normal data of pain-related evoked potentials (PREP) elicited with a concentric surface electrode among normal, healthy adults and the relationship between PREP and pain intensity.MethodsSixty healthy volunteers (22 men and 38 women; aged 36.4±10.7 years; height, 165.4±7.8 cm) were enrolled. Routine nerve conduction study (NCS) was done to measure PREP following electrical stimulation of hands (C7 dermatome) and feet (L5 dermatome). Negative peak (N), positive peak (P) latencies, peak to peak (NP) amplitudes, conduction velocity (CV), and verbal rating scale (VRS) score were obtained. Linear regression analysis tested for significant relevance between variables of PREP and VRS score.ResultsNormal NCS results were obtained in all subjects. N latency of hand PREP was 163.8 ±40.0 ms (right) and 161.0±39.9 ms (left). N latency of foot PREP was 178.0±43.9 ms (right), 180.4±43.4 ms (left). NP amplitude of hands was 20.6±10.6 µV (right) and 21.9±11.6 µV (left). NP amplitude of feet was 18.8±8.3 µV (right) and 19.0±8.4 µV (left). The calculated CV was 13.2±4.7 m/s and VRS score was 3.8±1.0. A highly significant positive correlation was evident between VRS score and NP amplitude (y=0.1069x+1.781, r=0.877, n=60, p<0.0001).ConclusionPREP among normal, healthy adults revealed a statistically significant correlation between PREP amplitude and VRS score.

Peripheral NMDA Receptors Mediate Antidromic Nerve Stimulation-Induced Tactile Hypersensitivity in the Rat.

We investigated the role of peripheral NMDA receptors (NMDARs) in antidromic nerve stimulation-induced tactile hypersensitivity outside the skin area innervated by stimulated nerve. Tetanic electrical stimulation (ES) of the decentralized L5 spinal nerve, which induced enlargement of plasma extravasation, resulted in tactile hypersensitivity in the L4 plantar dermatome of the hind-paw. When intraplantar (i.pl.) injection was administered into the L4 dermatome before ES, NMDAR and group-I metabotropic Glu receptor (mGluR) antagonists and group-II mGluR agonist but not AMPA/kainate receptor antagonist prevented ES-induced hypersensitivity. I.pl. injection of PKA or PKC inhibitors also prevented ES-induced hypersensitivity. When the same injections were administered after establishment of ES-induced hypersensitivity, hypersensitivity was partially reduced by NMDAR antagonist only. In naïve animals, i.pl. Glu injection into the L4 dermatome induced tactile hypersensitivity, which was blocked by NMDAR antagonist and PKA and PKC inhibitors. These results suggest that the peripheral release of Glu, induced by antidromic nerve stimulation, leads to the expansion of tactile hypersensitive skin probably via nociceptor sensitization spread due to the diffusion of Glu into the skin near the release site. In addition, intracellular PKA- and PKC-dependent mechanisms mediated mainly by NMDAR activation are involved in Glu-induced nociceptor sensitization and subsequent hypersensitivity.

CSM 2015 Orthopaedic Section Platform Presentations (Abstracts OPL1–OPL63)

CSM 2015 Orthopaedic Section Platform Presentations (Abstracts OPL1–OPL63)