Nerve In Man Research Articles

Ultrasound-guided, open-source microneurography: Approaches to improve recordings from peripheral nerves in man

ObjectiveMicroneurography is the only method for recording from single neurons in intact human nerves. It is challenging - requiring technical expertise, investment in specialised equipment and has sparse data yields. MethodsWe assessed whether ultrasound guidance in combination with an ‘open access’ amplifier and data capture system (Open-Ephys) would simplify and expand the scope of microneurographic recordings in humans. ResultsIn 32 healthy consenting volunteers, ultrasound-guidance improved success rates for obtaining cutaneous C-fibres and reduced “Skin to Nerve” times from 28.5 min to 4.5 min for recordings of the peroneal nerve (P < 0.0001).We illustrate the potential utility of ultrasound-guided microneurography for difficult to access nerves with phrenic nerve recording during a Valsalva manoeuvre.We show that Open Ephys is a viable alternative to commercially available recording systems and offers advantages in terms of cost and software customisability. ConclusionsUltrasound guidance for microneurography with Open Ephys facilitates cutaneous C nociceptor recordings and allows recordings to be made from nerves previously considered inaccessible. SignificanceWe anticipate that the adoption of these techniques will improve microneurography experimental efficiency, adds an important visual learning aid and increases the generalisability of the approach.

Study of communication between musculocutaneous and median nerves in man

IntroductionThe median and musculocutaneous nerves are functionally most important terminal branches of brachial plexus. Injuries involving median or musculocutaneous nerve proximal to the anastomotic branch may give rise to unexpected presentation of weakness of forearm flexor and thenar muscles or present as double nerve injury. This inspired us to study the exact topography of communication between median nerve and musculocutaneous nerve and to discuss its morphological and clinical significance. MethodsThe study was conducted in 50 cadavers (100 upper limbs) in duration of two and a half years. Proper cadaveric dissection was done during 2010–2013 in the department of Anatomy, Jawaharlal Nehru Medical College, and also in department of Anatomy Mahatma Gandhi Aurvadic Medical College, Sawangi, Wardha. ResultPresent series, studied musculocutaneous and median nerves in 50 cadavers (100 upper limbs) to evaluate the communication between these two nerves. In 42% cadavers (2-bilateral and 19 –unilateral) communicating branch was present, mostly single and distal to coracobrachialis muscle. More than one communicating branch was observed in 4% cadavers. DiscussionThe incidence of communication between musculocutaneous and median nerve is quite high (42%). Previous studies carried out in different countries and ethnicities showed abnormal communication between these two nerves ranged from 6–68%.Lesions of communicating nerve may give rise to pattern of weakness that may impose difficulty in diagnosis. So it is important to have awareness of these variations that are observed and discussed in present study.

Injury to the perineal branch of the pudendal nerve in men: Outcomes from surgical resection of the perineal branches.

The objective is to report the outcome of an anterior surgical approach to treat neuroma of the perineal branch of the pudendal nerve (PBPN). An IRB-approved prospective study enrolled 14 consecutive male patients from 2011 through 2015 who had symptoms of perineal/scrotal pain. Each patient had a successful, diagnostic, pudendal nerve block. The surgical procedure was resection of the PBPN and implantation of the nerve into the obturator internus muscle. Mean age at surgery was 50±15years. Median duration of pain symptoms was 5.5years (range 1.2-42.9years). Mechanisms of injury was exercise (6/14), prostatectomy (4/14), and falls (4/14). Outcomes were the Male Pudendal Pain Functional Questionnaire (MQ), and the Numeric Pain Rating Scale (NPRS). The mean postoperative follow-up was 26±14months. The MQ demonstrated that after surgery, patients overall had significantly less disability due to pudendal pain (P<.03). The NPRS revealed that pain significantly improved (P<.004). Resection of the PBPN and implantation of this nerve into the obturator internus muscle significantly relieved men's pelvic pain disability.

Flexible adaptation to an artificial recurrent connection from muscle to peripheral nerve in man.

Controlling a neuroprosthesis requires learning a novel input-output transformation; however, how subjects incorporate this into limb control remains obscure. To elucidate the underling mechanisms, we investigated the motor adaptation process to a novel artificial recurrent connection (ARC) from a muscle to a peripheral nerve in healthy humans. In this paradigm, the ulnar nerve was electrically stimulated in proportion to the activation of the flexor carpi ulnaris (FCU), which is ulnar-innervated and monosynaptically innervated from Ia afferents of the FCU, defined as the "homonymous muscle," or the palmaris longus (PL), which is not innervated by the ulnar nerve and produces similar movement to the FCU, defined as the "synergist muscle." The ARC boosted the activity of the homonymous muscle and wrist joint movement during a visually guided reaching task. Participants could control muscle activity to utilize the ARC for the volitional control of wrist joint movement and then readapt to the absence of the ARC to either input muscle. Participants reduced homonymous muscle recruitment with practice, regardless of the input muscle. However, the adaptation process in the synergist muscle was dependent on the input muscle. The activity of the synergist muscle decreased when the input was the homonymous muscle, whereas it increased when it was the synergist muscle. This reorganization of the neuromotor map, which was maintained as an aftereffect of the ARC, was observed only when the input was the synergist muscle. These findings demonstrate that the ARC induced reorganization of neuromotor map in a targeted and sustainable manner.

The morphological substrate for Renal Denervation: Nerve distribution patterns and parasympathetic nerves. A post-mortem histological study

BackgroundRenal Denervation as a possible treatment for hypertension has been studied extensively, but knowledge on the distribution of nerves surrounding the renal artery is still incomplete. While sympathetic and sensory nerves have been demonstrated, there is no mention of the presence of parasympathetic nerve fibers. ObjectivesTo provide a description of the distribution patterns of the renal nerves in man, and, in addition, provide a detailed representation of the relative contribution of the sympathetic, parasympathetic and afferent divisions of the autonomic nervous system. MethodsRenal arteries of human cadavers were each divided into four longitudinal segments and immunohistochemically stained with specific markers for afferent, parasympathetic and sympathetic nerves. Nerve fibers were semi-automatically quantified by computerized image analysis, and expressed as cross-sectional area relative to the distance to the lumen. ResultsA total of 3372 nerve segments were identified in 8 arteries of 7 cadavers. Sympathetic, parasympathetic and afferent nerves contributed for 73.5% (95% CI: 65.4–81.5%), 17.9% (10.7–25.1%) and 8.7% (5.0–12.3%) of the total cross-sectional nerve area, respectively. Nerves are closer to the lumen in more distal segments and larger bundles that presumably innervate the kidney lie at 1–3.5mm distance from the lumen. The tissue-penetration depth of the ablation required to destroy 50% of the nerve fibers is 2.37mm in the proximal segment and 1.78mm in the most distal segments. ConclusionSympathetic, parasympathetic and afferent nerves exist in the vicinity of the renal artery. The results warrant further investigation of the role of the parasympathetic nervous system on renal physiology, and may contribute to refinement of the procedure by focusing the ablation on the most distal segment.

Mechanisms of nerve injury in leprosy

All patients with leprosy have some degree of nerve involvement. Perineural inflammation is the histopathologic hallmark of leprosy, and this localization may reflect a vascular route of entry of Mycobacterium leprae into nerves. Once inside nerves, M leprae are ingested by Schwann cells, with a wide array of consequences. Axonal atrophy may occur early in this process; ultimately, affected nerves undergo segmental demyelination. Knowledge of the mechanisms of nerve injury in leprosy has been greatly limited by the minimal opportunities to study affected nerves in man. The nine-banded armadillo provides the only animal model of the pathogenesis of M leprae infection. New tools available for this model enable the study and correlation of events occurring in epidermal nerve fibers, dermal nerves, and nerve trunks, including neurophysiologic parameters, bacterial load, and changes in gene transcription in both neural and inflammatory cells. The armadillo model is likely to enhance understanding of the mechanisms of nerve injury in leprosy and offers a means of testing proposed interventions.

Electrical Stimulation of the Posterior Tibialis Nerve Improves Symptoms of Poststroke Neurogenic Overactive Bladder in Men: A Randomized Controlled Trial

To evaluate the effectiveness of electrical stimulation of the posterior tibialis nerve in men with neurogenic overactive bladder secondary to ischemic stroke at 45 days and 12 months after treatment. We studied 24 patients older than 18 years, with ischemic stroke that occurred between 6 months and 3 years previously and with no prior urinary symptoms. These patients were randomly allocated to receive electrical stimulation of the posterior tibialis nerve twice weekly for 6 weeks (treatment group, n = 12) or general advice and stretching sessions 1 to 3 times monthly for 6 weeks (control group, n = 12). Each session lasted 30 minutes in both groups. The primary outcomes were reduction in urinary frequency, reduction in urinary urgency, and overall improvement in voiding diary variables. Patients in the electrical stimulation group, in relation to baseline and to control group, experienced improvement in urinary symptoms, reducing urinary urgency and frequency, and reported subjective improvement after treatment. This effect persisted after 12 months of follow-up. The patients with lesion in right hemisphere, advanced age, and with higher body mass index presented more chance to develop urinary symptoms. Electrical stimulation of the posterior tibialis nerve is a safe and effective option for the treatment of poststroke neurogenic overactive bladder in men, reducing urinary frequency and urgency.

Anatomic Assessment of Sympathetic Peri-Arterial Renal Nerves in Man

BackgroundAlthough renal sympathetic denervation therapy has shown promising results in patients with resistant hypertension, the human anatomy of peri-arterial renal nerves is poorly understood. ObjectivesThe aim of our study was to investigate the anatomic distribution of peri-arterial sympathetic nerves around human renal arteries. MethodsBilateral renal arteries were collected from human autopsy subjects, and peri-arterial renal nerve anatomy was examined by using morphometric software. The ratio of afferent to efferent nerve fibers was investigated by dual immunofluorescence staining using antibodies targeted for anti–tyrosine hydroxylase and anti–calcitonin gene–related peptide. ResultsA total of 10,329 nerves were identified from 20 (12 hypertensive and 8 nonhypertensive) patients. The mean individual number of nerves in the proximal and middle segments was similar (39.6 ± 16.7 per section and 39.9 ± 1 3.9 per section), whereas the distal segment showed fewer nerves (33.6 ± 13.1 per section) (p = 0.01). Mean subject-specific nerve distance to arterial lumen was greatest in proximal segments (3.40 ± 0.78 mm), followed by middle segments (3.10 ± 0.69 mm), and least in distal segments (2.60 ± 0.77 mm) (p < 0.001). The mean number of nerves in the ventral region (11.0 ± 3.5 per section) was greater compared with the dorsal region (6.2 ± 3.0 per section) (p < 0.001). Efferent nerve fibers were predominant (tyrosine hydroxylase/calcitonin gene–related peptide ratio 25.1 ± 33.4; p < 0.0001). Nerve anatomy in hypertensive patients was not considerably different compared with nonhypertensive patients. ConclusionsThe density of peri-arterial renal sympathetic nerve fibers is lower in distal segments and dorsal locations. There is a clear predominance of efferent nerve fibers, with decreasing prevalence of afferent nerves from proximal to distal peri-arterial and renal parenchyma. Understanding these anatomic patterns is important for refinement of renal denervation procedures.

Abraham Guz (1929-2014).

How do you describe a giant? As a person of abnormally great stature; above the usual size; or someone with much greater powers than the average person? Abraham Guz (‘Abe’) was not a tall man, but he was a scientific giant with an absolute desire to understand and find the scientific truth. This drive led him to make many original contributions in respiratory and cardiovascular physiology. Indeed, a simple literature search produces over 250 peer reviewed papers spanning some 50 years, the top 25 of which have been quoted over 2500 times. Moreover, most of his outstanding work was published in The Journal of Physiology, and we received it with gratitude because it was always insightful and ahead of its time. Many will argue that counting citations is a poor measure of scientific endeavour and I suspect Abe himself would certainly agree. However, this approach did provide us with a place to start when faced with the task of bringing together Abe's huge and varied scientific contributions.

Nerve conduction studies in the upper limb in the malwa region-normative data.

To establish the normal electrophysiological data for the median and the ulnar nerves in normal healthy adults in the Malwa region of Punjab, India. Nerve conduction studies were performed prospectively in the upper limbs of 100 carefully screened, healthy individuals of either sex, who were between the ages of 20 and 60 years, by using a standardized technique. Motor studies: The median distal latency (DL) in men was 3.4 (0.2) ms, the amplitude (CMAPA) was 10.80 (2.8) mV, the conduction velocity (MNCV) was 55.6 (2.5) m/s and the F-wave (min latency) was 27.57±2.54(21.5-34.2). In the ulnar nerve , the motor DL was 2.34 (0.25) ms, the amplitude (CMAPA) was 9.8(2.6) mV, MNCV was 63.4 (3.0) m/s and the F-Wave(min latency) was 26.29±2.12(21.6-34.7). In the sensory studies, the median nerve DL was 2.0(0.35) ms, SNCV was 53.4±3.0 m/s and the amplitude (SNAPA)was 59.3 (16.4) μV for men and it was 68.7(28.4) μV for women. For the ulnar nerve in men, the DL was 1.85(0.25)ms, SNCV was 55.5 (4.1) m/s and the amplitude(SNAPA) was 55.5 (18.4) μV for men and it was 64.9 (16.8) μV for women. Only the gender showed a statistically significant effect on the sensory nerve action potential for the median (p < 0.04) and the ulnar nerves (p < 0.041). The normative conduction parameters of the commonly tested nerves in the upper limb were established in our EMG lab. The mean motor nerve conduction parameters for the median and the ulnar nerves correlated favourably with the existing literature data. However, for the sensory nerves, a higher value for the nerve action potential amplitude was demonstrated in this study.

An unusual communication between the mylohyoid and lingual nerves in man: Its significance in lingual nerve injury

The mylohyoid nerve is the branch of the inferior alveolar nerve (IAN) which arises above the mandibular foramen. An abnormal communication between the mylohyoid nerve and lingual nerve (LN) was noted during the routine dissection of a male cadaver. Communicating branches between IAN and LN have been identified as a possible explanation for the inefficiency of mandibular anesthesia. The communication between mylohyoid and lingual nerve was found in this case after the LN passes in close relation to third molar tooth, which makes it more susceptible to injury during third molar extractions.

Action potentials from sensory nerve in man: physiology and clinical application.

Action potentials from sensory nerve in man: physiology and clinical application.

Sural nerve and short saphenous vein entrapment-a case report

AbstractAlthough the sural nerve is the most extensively studied nerve in man, there is a dearth of data regarding the normal variations in the size and distribution of axons in normal subjects. Since the sural nerve is the most frequently used sensory nerve in nerve transplantation, knowledge of variations in its course and distribution plays an important role in the surgical procedures. Here, an entrapment of the sural nerve in the gastrocnemius is reported. The short saphenous vein also passed through the gastrocnemius muscle along with the sural nerve.

Sural nerve and short saphenous vein entrapment-a case report

Although the sural nerve is the most extensively studied nerve in man, there is a dearth of data regarding the normal variations in the size and distribution of axons in normal subjects. Since the sural nerve is the most frequently used sensory nerve in nerve transplantation, knowledge of variations in its course and distribution plays an important role in the surgical procedures. Here, an entrapment of the sural nerve in the gastrocnemius is reported. The short saphenous vein also passed through the gastrocnemius muscle along with the sural nerve.

The cisternal segment of the abducens nerve in man: three-dimensional MR imaging

Purpose: The goal of this study was to identify the abducens nerve in its cisternal segment by using three-dimensional turbo spin echo T2-weighted image (3DT2-TSE). The abducens nerve may arise from the medullopontine sulcus by one singular or two separated rootlets. Material and methods: We studied 285 patients (150 males, 135 females, age range: 9–72 years, mean age: 33.3±14.4) referred to MR imaging of the inner ear, internal auditory canal and brainstem. All 3D T2-TSE studies were performed with a 1.5 T MR system. Imaging parameters used for 3DT2-TSE sequence were TR:4000, TE:150, and 0.70 mm slice thickness. A field of view of 160 mm and 256×256 matrix were used. The double rootlets of the abducens nerve and contralateral abducens nerves and their relationships with anatomical structures were searched in the subarachnoid space. Results: We identified 540 of 570 abducens nerves (94.7%) in its complete cisternal course with certainty. Seventy-two cases (25.2%) in the present study had double rootlets of the abducens nerve. In 59 of these cases (34 on the right side and 25 on the left) presented with unilateral double rootlets of the abducens. Thirteen cases presented with bilateral double rootlets of the abducens (4.5%). Conclusion: An abducens nerve arising by two separate rootlets is not a rare variation. The detection of this anatomical variation by preoperative MR imaging is important to avoid partial damage of the nerve during surgical procedures. The 3DT2-TSE as a noninvasive technique makes it possible to obtain extremely high-quality images of microstructures as cranial nerves and surrounding vessels in the cerebellopontine cistern. Therefore, preoperative MR imaging should be performed to detect anatomical variations of abducens nerve and to reduce the chance of operative injuries.

Spatial relationships between masticatory muscles and their innervating nerves in man with special reference to the medial pterygoid muscle and its accessory muscle bundle.

The relationships between the positional arrangement of the surrounding and innervating nerves of the muscles supplied by the mandibular nerve, in particular those medial to the main trunk of the nerve, were examined in 24 head halves from 12 Japanese cadavers by dissection from the inside after removal of the bony elements except for the mandible. In ten sides of five heads, the lingual nerve pierced the medial pterygoid muscle, and the bundle lateral to the nerve was found to be separated as an accessory muscle bundle. The accessory bundle was frequently attached to the mylohyoid muscle. In addition, the inferior alveolar nerve and the lingual nerve frequently communicated, and in four specimens a branch from the lingual nerve entered the mylohyoid to communicate with the proper nerve. The innervation pattern indicated that the medial pterygoid muscle consists of the anteromedial and the posterolateral main parts, and sometimes has an accessory bundle. Based on the present findings and the previous studies of the positional relationships between the muscles and nerves by our research group, we propose that the muscles innervated by the mandibular nerve could be classified as an inner group (the lateral pterygoid) and an outer group (the other muscles). A possible scheme of the positional relationships between the muscles and nerves is presented.

Catheter stimulation of cardiac parasympathetic nerves in man: a novel technique

Catheter stimulation of cardiac parasympathetic nerves in man: a novel technique

Anatomical evidence for the absence of a morphologically distinct cranial root of the accessory nerve in man.

The accessory nerve is conventionally described as having a cranial and spinal root. According to standard descriptions the cranial root (or part) is formed by rootlets that emerge from the medulla between the olive and the inferior cerebellar peduncle. These rootlets are considered to join the spinal root, travel with it briefly, then separate within the jugular foramen to become part of the vagus nerve. In 15 fresh specimens we exposed the posterior cranial fossa with a coronal cut through the foramen magnum and explored the course of each posterior medullary rootlet (PMR) arising from within the retro-olivary groove. We chose the caudal end of the olive as the landmark for the caudal end of the medulla. In all specimens every PMR that did not contribute to the glossopharyngeal nerve joined the vagus nerve at the jugular foramen. The distance between the caudal limit of the olive and the origin of the most caudal PMR that contributed to the vagus nerve ranged from 1-21 mm (mean = 8.8 mm). All rootlets that joined the accessory nerve arose caudal to the olive. The distance from the caudal limit of the olive and the most rostral accessory rootlet ranged from 1-15 mm (mean = 5.4 mm). We were unable to demonstrate any connection between the accessory and vagus nerves within the jugular foramen. Our findings indicate that the accessory nerve has no cranial root; it consists only of the structure hitherto referred to as its spinal root.

Sensory nerves in man and their role in primary headaches.

The sensory innervation of intracranial vessels originate in the trigeminal ganglion and comprise the following signal substances; calcitonin gene-related peptide (CGRP), substance P, neurokinin A, pituitary adenylate cyclase activating peptide (PACAP) and nitric oxide (NO). Studies in patients have revealed a clear association between head pain and the release of CGRP. In cluster headache and in a case of chronic paroxysmal headache there is in addition release of vasoactive intestinal peptide (VIP), which was associated with the facial symptoms (nasal congestion, rhinorrhea). In parallel with triptan administration, acting via 5-HT(1B/1D) receptors, head pain subside and neuropeptide release normalise. These data show the involvement of sensory and parasympathetic mechanisms in the pathophysiology of primary headaches.

Sensory nerves in man and their role in primary headaches

Sensory nerves in man and their role in primary headaches