Tibial Nerve Trunk Research Articles

Comparing Nerve Versus Muscle Wide-Pulse High-Frequency Electrical Stimulation for Maximal and Submaximal Efforts.

The effectiveness of neuromuscular electrical stimulation hinges on the evoked torque level, which can be attained through either conventional (CONV) or wide-pulse high frequency (WPHF). However, the best electrode placement is still unclear. This study adopted a crossover design to compare the effects of WPHF applied to the tibial nerve trunk (N-WPHF) or muscle (M-WPHF) with CONV in healthy participants. A total of 30 participants (age: 22.4 [4.5]) were involved in 4 sessions. During each session, participants performed: 2 maximal voluntary contractions, 2 contractions at maximal evoked torque, and 2 contractions at submaximal evoked torque at 20% maximal voluntary contraction. Neuromuscular electrical stimulation intensity-evoked torque, efficiency, and discomfort were measured in maximal and submaximal conditions. Statistical analyses were conducted using a 1-way mixed-model analysis of variance with repeated measures. N-WPHF and M-WPHF showed higher evoked torque than CONV (P = .002 and P = .036) and greater efficiency than CONV for maximal evoked torque (P = .006 and P = .002). N-WPHF induced higher efficiency than M-WPHF and CONV for submaximal evoked torque (P = .004). Higher discomfort was observed for both N-WPHF and M-WPHF for submaximal evoked torque compared with CONV (P = .003 and P < .001). Our results suggest that WPHF applied at either the nerve or muscle could be the best choice for the maximal condition, whereas nerve application is preferred for the submaximal condition.

How I do it: selective tibial neurotomy.

Selective neurotomy is known as an effective method to reduce focal spasticity when medical treatment including botulinum toxin is not sufficient. The tibial nerve can be targeted to treat spastic equinovarus foot with (or without) claw toes. Tibial nerve trunk is dissected in the popliteal fossa. Sensitive and motor branches are identified using electrical stimulation to monitor motor responses. The muscular nerves corresponding to the targeted muscles are partially sectioned according to a preoperative chart. A postoperative rehabilitation program is mandatory. Precise and rigorous selective neurotomy provided a definitive and safe treatment for spastic equinovarus foot.

Widespread Pressure Pain Hypersensitivity in Musculoskeletal and Nerve Trunk Areas as a Sign of Altered Nociceptive Processing in Unilateral Plantar Heel Pain

Our aim was to investigate the differences in pressure sensitivity over musculoskeletal and nerve symptomatic and distant areas between individuals with plantar heel pain and healthy subjects and to determine the relationship between sensitivity to pressure pain, foot pain, and fascia thickness. Thirty-five patients with unilateral chronic plantar heel pain and 35 matched healthy controls participated. Pressure pain thresholds (PPTs) were assessed bilaterally over several nerve trunks (median, radial, ulnar, common peroneal, tibial, and sural nerve trunks) and musculoskeletal structures (calcaneus, medial gastrocnemius, tibialis anterior, and second metacarpal) by an assessor blinded to the subject's condition. Pain was assessed with a numerical pain rating scale (0–10), impact of foot pain was assessed with the Foot Function Index, and plantar fascia thickness was measured via ultrasound imaging. Analysis of covariance revealed lower widespread and bilateral PPTs over both nerve trunks and musculoskeletal structures in individuals with plantar heel pain (P < .001). Female patients showed lower PPT than male patients in almost all points (P < .001). PPT over the peripheral nerve trunks of the lower extremity were significantly associated with the intensity of pain at first step in the morning and with the foot function disability scale of the Foot Function Index (P < .05). This study found widespread pressure pain hypersensitivity over both nerve trunks and musculoskeletal structures in individuals with unilateral chronic plantar heel pain, suggesting the presence of a central altered central nociceptive pain processing. Pressure hypersensitivity over nerve trunks on the lower extremity was associated with higher pain intensity and related disability. PerspectivesThis study found widespread pressure hypersensitivity over both nerve trunks and musculoskeletal structures in individuals with unilateral chronic plantar heel pain, as a manifestation of a centrally altered central nociceptive pain processing.

Test-retest reliability of wide-pulse high-frequency neuromuscular electrical stimulation evoked force.

We compare forces evoked by wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (NMES) delivered to a nerve trunk versus muscle belly and assess their test-retest intraindividual and interindividual reliability. Forces evoked during 2 sessions with WPHF NMES delivered over the tibial nerve trunk and 2 sessions over the triceps surae muscle belly were compared. Ten individuals participated in 4 sessions involving ten 20-s WPHF NMES contractions interspaced by 40-s recovery. Mean evoked force and force time integral of each contraction were quantified. For both nerve trunk and muscle belly stimulation, intraindividual test-retest reliability was good (intraclass correlation coefficient > 0.9), and interindividual variability was large (coefficient of variation between 140% and 180%). Nerve trunk and muscle belly stimulation resulted in similar evoked forces. WPHF NMES locations might be chosen by individual preference because intraindividual reliability was relatively good for both locations. Muscle Nerve 57: E70-E77, 2018.

Ligation-and-Bypass Technique through the Posterior Approach for Bilateral Popliteal Aneurysms

A 56-year-old man with a painful, progressively enlarging pulsatile mass in the bilateral popliteal fossae was diagnosed with a bilateral popliteal artery aneurysm (PAA) and referred to our hospital to undergo surgical therapy. Computed tomographic scanning demonstrated a large, middle-type PAA with a rich mural thrombus in the bilateral popliteal arteries. Following aneurysm exclusion posteriorly, the patient underwent bypass surgery using a ringed polytetrafluoroethylene graft bilaterally. This procedure was chosen to prevent nerve injury caused by mobilization of the adherent nerves and aneurysmal resection. The patient had a satisfactory postoperative course. This procedure may be recommended for large, middle-type PAAs because (1) the adherent tibial nerve trunk and its branch nerves can be protected by aneurysm exclusion with arterial branch ligation and (2) frequently occurring postexclusion expansion of the aneurysm caused by insufficient branch ligation using the medial approach can be avoided.

An experimental study of promoting peripheral nerve regeneration through slow-releasing diaphragm with FK506 after end-to-side neurorrhaphy

目的 探讨免疫抑制剂FK506缓释膜片局部应用对周围神经端-侧吻合后神经再生的影响.方法选用SD大白鼠40只,随机平均分成实验组和对照组.实验组:切断腓总神经,在邻近的胫神经干外膜上开一1 mm窗口,将腓总神经远端与胫神经干做端-侧神经吻合后在吻合口周围放置含有FK06分子可降解缓释膜片.对照组:单纯行神经端-侧吻合.两组分别于术后2、4、8、12周取材,对腓总神经和胫神经干用快蓝(FB)和荧光金(FG)注射标记,取背根神经节(DRG)和脊髓在荧光显微镜下观察被标记细胞.结果实验组背根神经节和脊髓内FB标记细胞明显多于对照组.结论免疫抑制剂FK506能促进外周神经端-侧吻合后神经再生的速度和质量。

Topography of the distal tibial nerve and its branches.

The tibial nerve trunk and its branches were dissected in 20 embalmed cadaver legs and the relative topographic anatomy was defined at 3-cm intervals up to 15 cm proximal to the medial malleolar-calcaneal (MMC) axis. Each nerve branch was found in various locations. The calcaneal nerve was found to descend from medial to posteromedial. It was never found anterolaterally and only rarely laterally. The lateral plantar nerve was found to rotate externally from lateral and posterolateral to lateral and posteromedial as it descends. This nerve was not found medially or anteromedially. The first branch of the lateral plantar nerve was indistinguishable from the trunk of the tibial nerve descending medially to between the lateral plantar and calcaneal nerves. The overall pattern of the medial plantar nerve was an internal rotation from anteromedial (proximal) to anterior (distally). It was not found posteriorly. The flexor hallucis longus motor branch was located an average of 17.9 cm (range, 10-24 cm) proximal to the MMC axis. Preliminary application of these data has facilitated surgical dissection and afforded an understanding of how tibial nerve trunk pathology correlates with clinical manifestations.

Nerve regeneration through a healthy peripheral nerve trunk as a nerve conduit: a preliminary study of a new concept in peripheral nerve surgery.

The popularity of nerve conduits has increased recently due to the need for alternative nerve reconstruction techniques, obviating the harvest of nerve grafts. Based on ideas suggesting nerve tissue itself, which was the most physiologic environment for nerve regeneration, a study using 40 sciatic nerves of 20 rats was performed. The proximal stumps of transected peroneal nerves were sutured to the lateral wall of healthy tibial nerve trunks after removal of the epineurium. Twelve weeks later, tissue samples were taken from the anastomosis sites and from the levels above and below these sites. Configurations of fascicles were evaluated, and numbers of fibers were estimated. It was observed that the fibers of peroneal nerves regenerated into and through the tibial nerve trunk distally. This suggested that active regenerating fibers of a proximal stump of a nerve could regenerate and progress as a fascicular unit in optimum condition at the trunk of another healthy nerve. This preliminary study should stimulate further studies based on this new concept: that a nerve trunk can serve as the host for the regenerating fibers of another nerve.

Nerve regeneration through side-to-side neurorrhaphy sites in a rat model: a new concept in peripheral nerve surgery.

Despite great improvement and refinements in nerve repair techniques, there were still problems in repair of peripheral nerve injuries for which proximal stumps were not available. In these circumstances for which classic end-to-end neurorrhaphy was impossible, new treatment modalities, benefiting by an adjacent healthy nerve, have been under investigation to overcome this problem. Therefore, end-to-side nerve repair with its modifications came to view and axonal passages through this site were shown. Moreover, the results were unsatisfactory or necessitating sacrifice of another healthy nerve. Three groups, containing 10 rats each, were included in the study. First was the control group, with end-to-end repair of the peroneal nerve. Second was the end-to-side repair group, in which the distal stump of the peroneal nerve trunk was anastomosed to the lateral side of the tibial nerve. The third was the side-to-side repair group. In this technique, 1-mm diameter epineural windows, both from peroneal and tibial nerve trunks facing each other, were removed and side-to-side neurorrhaphy was performed. After 3 weeks, as the second step, the peroneal nerve was sectioned proximally. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed by using walking track analysis. The number of myelinated fibers and fiber diameters were measured and an electron microscopic evaluation was carried out. Statistically, both in morphometric and gait analysis, the differences in values between the groups were significant in favor of the control group, followed by the side-to-side group. The study showed that axonal passage was possible with side-to-side technique and the functional results were satisfactory and superior to the end-to-side technique. Continuous supply of neurotrophic factors from their target cells was the probable cause of superior functional return in side-to-side repair, because both joining nerves were intact and healthy during the anastomosis procedure and after 3 weeks. It was concluded that this technique could be indicated in salvage of nerves in cases for which any intermediate segments would be removed, as in tumor ablation surgery, harvesting of nerve grafts, or both.

End-to-side neurorrhaphy supported by transposed active nerve fibers: its functional end result in a rat model

End-to-side nerve repair is an old-fashioned technique which has been abandoned since the beginning of this century. Recently, new treatment modalities have been investigated to overcome problems associated with peripheral nerve injury where the proximal stumps are not available. In this study, 30 rats were divided into three groups. In the first group the peroneal nerves were sectioned and their distal ends were sutured to the tibial nerve trunk. In the second group, the proximal part of the peroneal nerve was similarly sutured to the tibial trunk. A primary end-to-end neurorrhaphy performed on the peroneal nerves was the control group. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed using walking track analysis. The number of myelinated fibers and fiber diameters were measured, and an electron microscopic evaluation was carried out. With morphometric analysis, the values were significantly different in favor of the control group following the end-to-side repair technique. But, according to gait analysis, both groups had a similar satisfactory functional recovery; the classic end-to-side repair group had an unsatisfactory result. It is concluded that end-to-side neurorrhaphy, supported by transposed active nerve fibers, may result in a good integration network at the repair site and is a possible functional reconstruction model where the proximal stump is not available after peripheral nerve injury.

Effects of pyrethroid molecules on rat nerves in vitro: potential to reverse temperature-sensitive conduction block of demyelinated peripheral axons.

1. Prolongation of action potentials by cooling or pharmacological treatment can restore conduction in demyelinated axons. We have assessed the ability of pyrethroids (in vitro) to modify action potential kinetics and to reverse conduction block in lesioned peripheral nerve. 2. Fast Na+ currents were isolated in mammalian neuroblastoma (NIE115). Pyrethroids (4 microM) concurrently slowed inactivation and produced a spectrum of pronounced tail currents: s-bioallethrin (duration 12.2+/-7 ms), permethrin (24.2+/-3 ms) and deltamethrin (2230+/-100 ms). 3. Deltamethrin (5 microM) effected a slowly developing depression of compound action potential (CAP) amplitude in peroneal nerve trunks (P<0.05). Permethrin produced no net effect on CAP amplitude, area or repolarization time. 4. s-Bioallethrin (5 microM) enhanced CAP area, time for 90% repolarization and induced regenerative activity in a subpopulation of axons. 5. Tibial nerve trunks were demyelinated by lysolecithin (2 micro1) injection: 6-14 days later, slowly-conducting axons in the CAP (and peri-axonal microelectrode recordings) were selectively blocked by warming to 37 degrees C. 6. At 37 degrees C, s-bioallethrin (45 min, 5 microM) produced much greater after-potentials in lesioned nerves than in uninjected controls: area (P< 0.05) and relative amplitude ratios (P< 0.0001) were significantly altered. 7. In 3 of 4 cells (single-unit recording), s-bioallethrin restored conduction through axons exhibiting temperature-dependent block by raising blocking temperature (by 1.5 to > 3 degrees C) and reducing refractory period. 8. s-Bioallethrin induced temperature-dependent regenerative activity only in a sub-population of axons even after prolonged superfusion (> 1 h). 9. It was concluded that pyrethroids differentially alter Na+ current kinetics and action potential kinetics. The effects of s-bioallethrin are consistent with reversal of conduction block by demyelinated axons but regenerative/ectopic firing even in normal cells is likely to underpin its acknowledged neurotoxic actions and severely limit the clinical potential of this and related molecules.

Nerve regeneration after terminolateral neurorrhaphy: experimental study in rats.

Four methods of nerve terminolateral neurorrhaphy (TLN) were studied in rat experimental model. In Group A, the distal end of a severed peroneal nerve was sutured end-to-side with an intact tibial nerve trunk, without removal of the tibial epineurium at the suture site. In Group B, the distal end of a severed peroneal nerve was sutured end-to-side with the intact tibial nerve trunk, with removal of the tibial epineurium at the suture site. In Group C, a nerve segment was bridged between the distal part of the severed peroneal nerve and the intact tibial nerve with two end-to-side sutures. In Group D, the proximal end of a severed tibial nerve was sutured end-to-side with the peroneal nerve trunk. Through electrophysiologic, histologic, and ultrastructural examinations, the following conclusions were drawn: 1. Nerve regeneration is possible after TLN. 2. The regenerating fibers after TLN have the ability to penetrate the endoneurium, perineurium, and epineurium. 3. After different methods of TLN, the regenerating fibers grow in both a flowing-out and a filling-in fashion.

Nerve and muscle blood flow during hindlimb ischemia and reperfusion in rats.

Animal models of peripheral nerve ischemia have yielded variable results. The question of whether post-ischemia re-establishment of blood flow to the nerves augments injury has not been examined. To study this question, the ipsilateral common iliac and femoral arteries were occluded with arterial snares for 3 hours in rats; 14C-butanol tissue distribution was then used to measure blood flow in both sciatic and posterior tibial nerve trunks and in both biceps femoris muscles during occlusion and reperfusion. Clinical limb function was graded serially, with the undisturbed contralateral limb serving as the study control. Nerve blood flow was reduced throughout the ischemic period and was only 20% of the control value in the posterior tibial nerve. Muscle blood flow was unchanged. All rats had functional impairment, with an average limb function score of 7.5 (normal score < 2). During reperfusion, blood flow in the distal sciatic and posterior tibial nerves was approximately double that of control nerves at 2 hours, and muscle blood flow was also elevated. At 21 hours, tibial nerve blood flow was still twice that of the control nerve, but flows in the distal sciatic nerve and muscle were unchanged from control levels. Clinically, limb function improved progressively after reperfusion. It was concluded that nerve ischemia is attended by a relatively prolonged hyperemic flow response during reperfusion.

LIMB ISCHEMIA AND REPERFUSION

The relative importance of nerve versus muscle injury in limb ischemia-reperfusion is poorly understood. We used 14C-butanol tissue distribution to measure regional blood flow simultaneously in the proximal and distal sciatic, the posterior tibial nerve trunk (NBF), and biceps femoris muscle (MBF) of rats during 3 hours of occlusion of the ipsilateral iliac and femoral arteries and subsequently for up to 9 days of reperfusion. Limb motor function was also serially assessed. The contralateral limbs served as controls. Experimental groups were untreated control (n = 16); methylprednisolone, 30 mg/kg (n = 13); the lazaroid U74389F, 3 mg/kg (n = 13); and lazaroid vehicle (n = 13), i.v. 15 minutes before occlusion and 15 minutes after reperfusion. One hour after occlusion, NBF was -77% of the control value (p < 0.02) but MBF was unchanged (control NBF 15.2 +/- 3.3, control MBF 6.3 +/- 0.9, units mL.min-1 x 100 g-1). At both 2 and 21 hours of reperfusion, NBF was double that of control in all groups (p < 0.01); but MBF, which had been modestly elevated to 10.5 +/- 0.5 at 2 hours (p < 0.01), was already normal at 21 hours in all groups. During days 5 to 9 of reperfusion, NBF was still numerically elevated (NS); MBF remained at control. Functionally, test. limb scores were always grossly abnormal during occlusion (range: 7.1-8.5, normal = < 2). After 1 hour of reperfusion, all test limb scores were improved versus occlusion (p < 0.001, Wilcoxon rank-sum). Subsequently, there was gradual improvement in all groups, scores at 6 days ranging from 1.9 to 2.5. NBF is rapidly and severely reduced during ischemia. During reperfusion, the hyperemic flow response in nerve is more prolonged than in muscle. Limb dysfunction during ischemia and reperfusion may be largely the result of axonal or neuromuscular junction injury or both. Neither of the two treatments had effects on blood flow or limb function.

Continuous Postoperative Regional Analgesia by Nerve Sheath Block for Amputation Surgery-A Pilot Study

A pilot study of continuous postoperative regional analgesia by nerve sheath block for lower limb amputation is presented. At the time of exposure of sciatic or posterior tibial nerve trunks during above- or below-knee amputations in 11 patients with ASA physical status III or IV, a catheter was introduced directly into the transected nerve sheath for continuous infusion of 0.25% bupivacaine at a rate of 10 mL/h for 72 h. Effective amputation stump analgesia was obtained, significantly reducing the need for on-demand narcotic analgesics during this time to a mean dose equivalent of 1.4 mg of morphine compared with a retrospective control group who received the equivalent of a mean dose of 18.4 mg of morphine (P less than 0.0001). No complications related to the technique were observed. A follow-up of the group receiving continuous postoperative regional analgesia for up to 12 mo showed a total absence of phantom pain despite the presence of preoperative limb pain.

腰部脊柱管狭窄症の電気生理学的検討

Neurogenic claudication caused by exercise but relieved by rest is usually reliable symptom of lumbar spinal canal stenosis. 12 patients with lumbar canal stenosis were studied. They ranged in age from 64 to 85 years (mean, 74.5). There were 7 men and 5 women. These 12 patients were evaluated with treadmill exercise testing and spinal cord evoked potential after electrical stimulation to the tibial nerve trunks, caudal epidural anesthesia. In all of 12 patients, both electrical stimulation to the tibial nerve trunks and caudal epidural anesthesia significantly prolonged onset time of claudication.In 10 of 12 patients, the amplitudes in spinal cord evoked potential significantly decreased after treadmill exercising and recovered in 5 minutes.

Pathogenesis of diabetic neuropathy.

Samples of lumbosacral trunk, posterior tibial nerve, and sural nerve obtained at autopsy from diabetic and nondiabetic patients without mononeuropathy multiplex were evaluated using 1-mu-thick epoxy sections and teased nerve fiber preparations. Focal fascicular lesions characterized by reduced density of myelinated axons within fascicles were found predominantly in the specimens from diabetics, mainly in the posterior tibial nerve and lumbosacral trunk. In severe examples, the perineurium and even surrounding epineurium were damaged, stamping the lesions as ischemic. In addition, identical lesions were found in biopsies of nerves of nondiabetics with vasculitis. Density of myelinated fibers at the three sites demonstrated a proximal-distal graded loss that was significantly greater in the diabetic samples. The loss from the lumbosacral trunk to the posterior tibial nerve was correlated with the density of focal lesions in the lumbosacral trunk in the diabetic (p = 0.025), indicating that distal fiber loss was partly due to the focal lesions. Teased nerve fiber abnormalities were common only in sural nerves of diabetics, suggesting that they are secondary. We conclude that beyond the possible metabolic abnormalities involved in the genesis of diabetic polyneuropathy, focal fascicular lesions, likely due to diabetic microangiopathy, are also important in the development of diabetic neuropathy.

Differentiation of vasodilator and sudomotor responses in the cat paw pad to preganglionic sympathetic stimulation.

We monitored sweat secretion (using skin potential) and blood flow (using skin temperature) in the hind-paw skin of chloralose-anaesthetized cats pre-treated with guanethidine, and studied the responses to electrical stimulation of the ipsilateral lumbar sympathetic trunk. Stimulation caused sweat secretion and an increase in skin blood flow which was almost entirely restricted to the paw pads and was completely ipsilateral. Stimulation of the tibial nerve trunk produced similar effects, except that the increase in blood flow was more prolonged. The vasodilator effect of sympathetic trunk stimulation was not affected by chronic deafferentation of the paw. Atropine methonitrate (0.5-1 mg/kg I.V.) abolished the sudomotor response to sympathetic stimulation, but did not attenuate the blood flow response. Hexamethonium (1-2 mg/kg I.V.) abolished the vasodilator response to sympathetic stimulation, but did not affect the sudomotor response. Larger doses of hexamethonium (10-20 mg/kg) abolished both responses. The data suggest that the lumbar post-ganglionic neurones mediating vasodilatation in the skin of the cat paw pad are distinct from those that mediate sudomotor secretion.

Cutaneous and muscle afferent components of the cerebral potential evoked by electrical stimulation of human peripheral nerves

The cerebral potentials evoked by stimulation of the posterior tibial and sural nerves at ankle level were compared in normal human subjects. The latency of onset and latency to peak of the first positive wave were shorter by 5.6 msec and 6.7 msec respectively with posterior tibial stimulation. Stimulation of purely cutaneous posterior tibial afferents using ring electrodes around the hallux evoked a potential of longer latency than could be accounted for by the additional conduction time from hallux to ankle, indicating that the latencies of the cerebral potential evoked by posterior tibial stimulation at the ankle cannot be explained by the cutaneous afferents coursing in the nerve. Peripheral nerve conduction velocities were calculated for the ankle-popliteal fossa segment: in all subjects, the conduction velocity of the afferent potential due to posterior tibial stimulation at ankle level was 5–6 m/sec faster than the afferent potential due to purely cutaneous afferents in the sural or posterior tibial nerves. In one subject, muscle afferents in the posterior tibial nerve at the ankle were stimulated selectively using a microelectrode inserted into pure muscle nerve fascicles innervating the intrinsic muscles of the foot. The resulting cerebral potential had the same latency as the potential evoked by surface stimulation of the posterior tibial nerve trunk. It is concluded that in man group I muscle afferents from the lower limbs project to cerebral level and are responsible for the shorter latency of the cerebral potential evoked by stimulation of the posterior tibial nerve at the ankle. Appropriate calculations suggest that most of the discrepancy in the latencies of the cerebral potentials evoked by posterior tibial and sural stimulation may be attributed to the differences in conduction velocity of the primary afferent fibres.

Electrophysiological study of the peripheral nervous system in children. Changes in proximal and distal conduction velocities from birth to age 5 years.

Hoffman's reflex was evoked in the soleus muscle of 105 normal children from birth to age 5 years. This technique made it possible to determine conduction time and to estimate conduction velocity over the reflex arc. For 59 children, proprioceptive and motor distal nerve conduction velocities were calculated for the tibial nerve trunk. These measurements enabled the common changes for these three velocities to be described in terms of an exponential curve. Proximal conduction velocity has similar values to those of proprioceptive distal nerve fibres: it is always higher than motor nerve conduction velocity, but the difference gradually diminishes, remaining constant after the eighteenth month. Conduction time diminishes between birth and one year of age, whereas height increases. Then conduction time increases slowly, reaching at about age 5 years, when average height is 1050 mm, the value it had just after birth. For the child born at term, maturation of the nervous system is thus especially rapid during the first year of life.