An ultrasound-guided percutaneous electrical nerve stimulation regimen devised using finite element modeling promotes functional recovery after median nerve transection

Percutaneous electrical nerve stimulation of an injured nerve can promote and accelerate peripheral nerve regeneration and improve function.When performing acupuncture and moxibustion,locating the injured nerve using ultrasound before percutaneous nerve stimulation can help prevent further injury to an already injured nerve.However,stimulation parameters have not been standardized.In this study,we constructed a multi-layer human forearm model using finite element modeling.Taking current density and activated function as optimization indicators,the optimal percutaneous nerve stimulation parameters were established.The optimal parameters were parallel placement located 3 cm apart with the injury site at the midpoint between the needles.To validate the efficacy of this regimen,we performed a randomized controlled trial in 23 patients with median nerve transection who underwent neurorrhaphy.Patients who received conventional rehabilitation combined with percutaneous electrical nerve stimulation experienced greater improvement in sensory function,motor function,and grip strength than those who received conventional rehabilitation combined with transcutaneous electrical nerve stimulation.These findings suggest that the percutaneous electrical nerve stimulation regimen established in this study can improve global median nerve function in patients with median nerve transection.

Functional recovery and muscle atrophy in pre-clinical models of peripheral nerve transection and gap-grafting in mice:effects of 4-aminopyridine

We recently demonstrated a repurposing beneficial effect of 4-aminopyridine(4-AP),a potassium channel blocker,on functional recove ry and muscle atrophy after sciatic nerve crush injury in rodents.However,this effect of 4-AP is unknown in nerve transection,gap,and grafting models.To evaluate and compare the functional recovery,nerve morphology,and muscle atrophy,we used a novel stepwise nerve transection with gluing(STG),as well as 7-mm irreparable nerve gap(G-7/0)and 7-mm isografting in 5-mm gap(G-5/7)models in the absence and presence of 4-AP treatment.Following surgery,sciatic functional index was determined wee kly to evaluate the direct in vivo global motor functional recovery.After 12 weeks,nerves were processed for whole-mount immunofluorescence imaging,and tibialis anterior muscles were harvested for wet weight and quantitative histomorphological analyses for muscle fiber crosssectional area and minimal Feret's diameter.Average post-injury sciatic functional index values in STG and G-5/7 models were significantly greater than those in the G-7/0 model.4-AP did not affect the sciatic functional index recovery in any model.Compared to STG,nerve imaging revealed more misdirected axons and distorted nerve architecture with isografting.While muscle weight,cross-sectional area,and minimal Feret's diameter were significantly smaller in G-7/0 model compared with STG and G-5/7,4-AP treatment significantly increased right TA muscle mass,cross-sectional area,and minimal Feret's diameter in G-7/0 model.These findings demonstrate that functional recovery and muscle atrophy after peripheral nerve injury are directly related to the intervening nerve gap,and 4-AP exerts diffe rential effects on functional recove ry and muscle atrophy.

Serum response factor promotes axon regeneration following spinal cord transection injury

Studies have snown that serum response factor is beneficaial for axonar regeneration of peripheral herves.However,Its role after central nervous system injury remains unclear. In this study,we established a rat model of T9-T10 spinal cord transection injury.We found that the expression of serum response factor in injured spinal cord gray matter neurons gradually increased with time,reached its peak on the 7^(th) day,and then gradually decreased.To investigate the role of serum response factor,we used lentivirus vecto rs to ove rexpress and silence serum response factor in spinal cord tissue.We found that overexpression of serum response factor promoted motor function recovery in rats with spinal cord injury.Qualitative observation of biotinylated dextran amine anterograde tra cing showed that ove rexpression of serum response factor increased nerve fibers in the injured spinal co rd.Additionally,transmission electron microscopy showed that axon and myelin sheath morphology was restored.Silencing serum response factor had the opposite effects of ove rexpression.These findings suggest that serum response factor plays a role in the recovery of motor function after spinal cord injury.The underlying mechanism may be related to the regulation of axonal regeneration.

Expressions of nestin and glial fibrillary acidic protein in rat retina after optic nerve transection

AIM：To assess the expression of nestin and glial fibrillary acidic protein（GFAP）in rat retina after optic nerve transection.METHODS：Rats were randomly divided into normal control group,sham group and operation group,and used for establishing an animal model of optic nerve transection.Retinal specimen of each group was collected at 3,48h,7and 14d postoperative.Nestin and GFAP expressions on sagittal sections were analyzed by immunohistochemical staining,and protein extraction was analyzed by Western blot.RESULTS：Immunohistochemical analysis showed that nestin positive staining was rarely detected in normal control group and sham group,while sham group showed weak positive staining at 3h postoperative,the reaction gradually increased at 48h postoperative,and reached its maximum at 7d postoperative,and then decreased at 14d postoperative.Compared to the expression of GFAP,there was not statistically significant obvious difference among three groups（P〉0.05）.Result of Western blot method was consistent with that of immunohistochemical method.CONCLUSION：The expression of nestin increased in a time dependent fashion in Müller cells of retina following optic nerve transection,which was statistically significant,but there was no obvious difference in GFAP expression.The results indicate that an increase in colloid synthesis in retina following optic nerve transection can improve the retinal neurons’environment.

Etomidate affects the anti-oxidant pathway to protect retinal ganglion cells after optic nerve transection

Our previous studies revealed that etomidate, a non-barbiturate intravenous anesthetic agent, has protective effects on retinal ganglion cells within 7 days after optic nerve transection. Whether this process is related to anti-oxidative stress is not clear. To reveal its mechanism, we established the optic nerve transection injury model by transecting 1 mm behind the left eyeball of adult male Sprague-Dawley rats. The rats received an intraperitoneal injection of etomidate(4 mg/kg) once per day for 7 days. The results showed that etomidate significantly enhanced the number of retinal ganglion cells retrogradely labeled with Fluorogold at 7 days after optic nerve transection. Etomidate also significantly reduced the levels of nitric oxide and malonaldehyde in the retina and increased the level of glutathione at 12 hours after optic nerve transection. Thus, etomidate can protect retinal ganglion cells after optic nerve transection in adult rats by activating an anti-oxidative stress response. The study was approved by the Animal Ethics Committee at Air Force Medical University, China(approval No. 20180305) on March 5, 2018.

Expression of long non-coding RNAs in complete transection spinal cord injury: a transcriptomic analysis

Long non-coding RNAs(lncRNAs)are abundantly expressed in the central nervous system and exert a critical role in gene regulation via multiple biological processes.To uncover the functional significance and molecular mechanisms of lncRNAs in spinal cord injury(SCI),the expression signatures of lncRNAs were profiled using RNA sequencing(RNA-seq)technology in a Sprague-Dawley rat model of the 10th thoracic vertebra complete transection SCI.Results showed that 116 of 14,802 detected lncRNAs were differentially expressed,among which 16—including eight up-regulated(H19,Vof16,Hmox2-ps1,LOC100910973,Ybx1-ps3,Nnat,Gcgr,LOC680254)and eight down-regulated(Rmrp,Terc,Ngrn,Ppp2r2b,Cox6a2,Rpl37a-ps1,LOC360231,Rpph1)—demonstrated fold changes>2 in response to transection SCI.A subset of these RNA-seq results was validated by quantitative real-time PCR.The levels of 821 mRNAs were also significantly altered post-SCI;592 mRNAs were up-regulated and 229 mRNAs were down-regulated by more than 2-fold.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analyses showed that differentially expressed mRNAs were related to GO biological processes and molecular functions such as injury and inflammation response,wound repair,and apoptosis,and were significantly enriched in 15 KEGG pathways,including cell phagocytosis,tumor necrosis factor alpha pathway,and leukocyte migration.Our results reveal the expression profiles of lncRNAs and mRNAs in the rat spinal cord of a complete transection model,and these differentially expressed lncRNAs and mRNAs represent potential novel targets for SCI treatment.We suggest that lncRNAs may play an important role in the early immuno-inflammatory response after spinal cord injury.This study was approved by the Administration Committee of Experimental Animals,Guangdong Province,China.

Meta analysis of olfactory ensheathing cell transplantation promoting functional recovery of motor nerves in rats with complete spinal cord transection

OBJECTIVE： To evaluate the effects of olfactory ensheathing cell transplantation on functional recovery of rats with complete spinal cord transection. DATA SOURCES： A computer-based online search of Medline （1989-2013）, Embase （1989- 2013）, Cochrane library （1989-2013）, Chinese Biomedical Literature Database （1989-2013）, China National Knowledge Infrastructure （1989-2013）, VIP （1989-2013）, Wanfang databases （1989-2013） and Chinese Clinical Trial Register was conducted to collect randomized controlled trial data regarding olfactory ensheathing cell transplantation for the treatment of complete spinal cord transection in rats. SELECTION CRITERIA： Randomized controlled trials investigating olfactory ensheathing cell transplantation and other transplantation methods for promoting neurological functional recov- ery of rats with complete spinal cord transection were included in the analysis. Meta analysis was conducted using RevMan 4.2.2 software. MAIN OUTCOME MEASURES： Basso, Beattie and Bresnahan scores of rats with complete spinal cord transection were evaluated in this study. RESULTS： Six randomized controlled trials with high quality methodology were included. Meta analysis showed that Basso, Beattie and Bresnahan scores were significantly higher in the olfacto- ry ensheathing cell transplantation group compared with the control group （WMD = 3.16, 95% （21 （1.68, 4.65）; P 〈 0.00001）. CONCLUSION： Experimental studies have shown that olfactory ensheathing cell transplantation can promote the functional recovery of motor nerves in rats with complete spinal cord transection.

Glial scar size, inhibitor concentration, and growth of regenerating axons after spinal cord transection

A mathematical model has been formulated in accordance with cell chemotaxis and relevant experimental data. A three-dimensional lattice Boltzmann method was used for numerical simulation. The present study observed the effects of glial scar size and inhibitor concentration on regenerative axonal growth following spinal cord transection. The simulation test comprised two parts： （1） when release rates of growth inhibitor and promoter were constant, the effects of glial scar size on axonal growth rate were analyzed, and concentrations of inhibitor and promoters located at the moving growth cones were recorded. （2） When the glial scar size was constant, the effects of inhibitor and promoter release rates on axonal growth rate were analyzed, and inhibitor and promoter concentrations at the moving growth cones were recorded. Results demonstrated that （1） a larger glial scar and a higher release rate of inhibitor resulted in a reduced axonal growth rate. （2） The axonal growth rate depended on the ratio of inhibitor to promoter concentrations at the growth cones. When the average ratio was 〈 1.5, regenerating axons were able to grow and successfully contact target cells.

Identification of Differentially Expressed Proteins and Validation of the Changes of N-Ethylmaleimide-sensitive Factor in Rats with Focal Cerebral Ischemia after Transection of the Cervical Sympathetic Trunk

Stellate ganglion blockade （SGB） protects patients from focal cerebral ischemic injury, and transection of the cervical sympathetic trunk （TCST） in a rat model can mimic SGB in humans. The purpose of this study was to investigate the mechanisms underlying the neuroprotective effects of TCST on neuronal damage in the hippocampus in a rat model of middle cerebral artery occlusion （MCAO） in an attempt to elucidate the neuroprotective effects of SGB. The modified method of Zea Longa was used to establish the permanent MCAO model. Male Wistar rats were randomly divided into three groups： sham-operated group, MCAO group, and TCST group. The animals in TCST group were sacri- ficed 48 h after TCST which was performed after the establishment of the MCAO model. Proteins were extracted from the ipsilateral hippocampus and analyzed by two-dimensional difference gel electropho- resis （2D-DIGE） and peptide mass fingerprinting （PMF）. The levels of N-ethylmaleimide-sensitive fac- tor （NSF） were measured as well. The results showed that 11 types of proteins were identified by 2D- DIGE. The expressions of eight proteins were changed both in the sham-operated and TCST groups, and the expressions of the other three proteins were changed in all three groups. Moreover, the expres- sion of NSF was higher in the TCST group than in the MCAO group but lower in the MCAO group than in sham-operated group. The ratio of NSF expression between the MCAO group and sham- operated group was -1.37 （P〈0.05）, whereas that between the TCST group and MCAO group was 1.35 （P〈0.05）. Our results imply that TCST increases the expression of NSF in the hippocampus of adult rats with focal cerebral ischemia, which may contribute to the protection of the injured brain. Our study pro- vides a theoretical basis for the therapeutic application of SGB to patients with permanent cerebral ischemia.

Dark rearing maintains tyrosine hydroxylase expression in retinal amacrine cells following optic nerve transection

The present study examined changes in retinal tyrosine hydroxylase （TH） expression in rats having undergone optic nerve transection and housed under a normal day/night cycle or in the dark. The aim was to investigate the effects of amacrine cells on axonal regeneration in retinal ganglion cells and on the synapses that transmit visual signals. The results revealed that retinal TH expression gradually decreased following optic nerve transection in rats housed under a normal day/night cycle reaching a minimum at 5 days. In contrast, retinal TH expression decreased to a minimum at 1 day following optic nerve transection in dark reared rats, gradually increasing afterward and reaching a normal level at 5 7 days. The number of TH-positive synaptic particles correlated with the TH levels indicating that dark rearing can help maintain TH expression during the synaptic degeneration stage （5 7 days after optic nerve injury） in retinal amacrine cells.

Effects of targeted muscle reinnervation on spinal cord motor neurons in rats following tibial nerve transection

Targeted muscle reinnervation(TMR)is a surgical procedure used to transfer residual peripheral nerves from amputated limbs to targeted muscles,which allows the target muscles to become sources of motor control information for function reconstruction.However,the effect of TMR on injured motor neurons is still unclear.In this study,we aimed to explore the effect of hind limb TMR surgery on injured motor neurons in the spinal cord of rats after tibial nerve transection.We found that the reduction in hind limb motor function and atrophy in mice caused by tibial nerve transection improved after TMR.TMR enhanced nerve regeneration by increasing the number of axons and myelin sheath thickness in the tibial nerve,increasing the number of anterior horn motor neurons,and increasing the number of choline acetyltransferase-positive cells and immunofluorescence intensity of synaptophysin in rat spinal cord.Our findings suggest that TMR may enable the reconnection of residual nerve fibers to target muscles,thus restoring hind limb motor function on the injured side.

Laparoscopic step 1 ALPPS with microwave transection of theliver for Klatskin tumors:Is it worthwhile?

To the Editor：Associating liver partition and portal vein ligation for stagedhepatectomy （ALPPS） was introduced in 2007 [1]. This techniqueis now used worldwide and has a wide spectrum of indications.However, scientific debate and un-regulated surgical experimentationconcerning the application of this technique led the surgeons to organize the first Consensus Meeting [2] to build a scientificconsensus. One of the most controversial indications to ALPPS isits application for Klatskin tumors. The aim of this letter is to analyzethe critical aspects of laparoscopic microwave ALPPS for radicalsurgical treatment of Klatskin tumors.

Effects of C_8 ventral root avulsion or transection on spinal alpha motoneurons in adult rats A qualitative light and electron microscopic study

BACKGROUND： Nerve root avulsion is a frequent finding in patients with brachial plexus injury following road traffic accidents or as a result of severe arm traction during complicated deliveries. This injury constitutes a challenging clinical and surgical problem. The morphological characteristics of motoneurons after nerve root avulsion deserve further analysis. OBJECTIVE： To study the different morphological changes of α-motoneurons under light and electron microscopy after C8 spinal ventral rootlets avulsion and transection at various stages. DESIGN： Controlled animal study. SETTING： Department of Anatomy, King Faisal University. MATERIALS： The experiment was carried out at the Department of Anatomy, College of Medicine, King Faisal University between January 2005 and March 2006. Six adult Sprague Dawley rats weighing 200-350 g, irrespective of gender, were used for this study. The animals were bred at the animal house, College of Medicine, King Faisal University, and fed on rat maintenance diet. Water and standard diet were supplied ad libitum. Animal interventions were carried out according to animal ethical standards. METHODS： Three animals were randomly chosen for avulsion of the right ventral rootlets of C8 spinal nerves. The other three received transection of the right ventral rootlets of C8 spinal nerves. ①Avulsion experiment： After rats were anesthetized, the right ventral rootlets of C8 spinal nerves were identified. The ventral rootlets were avulsed from the spinal cord by traction with a fine hook （Fine Science Tools Inc., No. 10031-13, Germany）. Traction was exerted in a direction parallel to the course of the spinal root. Under the operating microscope, the C8 segment was exactly located. After checking the successfulness of the surgical procedure, the C8 segment was separated from the spinal cord. The outcome of the avulsion procedure was as follows： two animals had true avulsion, i.e., no remaining stump was attached to the spinal cord surface. One rat had a stump still attached. The animal was sacrificed I week later and was included in the transaction experiment for analysis. ②Transection experiment： Using fine scissors, the ventral rootlets were transected close to the area of the right ventral rootlets junction with the dorsal rootlets. MAIN OUTCOME MEASURES： After the rats were anesthetized, C8 spinal cord segments were collected for the avulsion experiment from 2 rats, 1 rat, and I rat at weeks 1, 4, and 8, respectively, and from 1 rat each after 4 and 8 weeks in the transection experiment. The morphology of α -motoneurons was observed under light microscopic and electron microscopic examination. RESULTS： All six rats were included in the final analysis. ①Avulsion experiment： α-motoneurons of the C8 spinal segment were found to survive avulsion injury up to 4 weeks. Thereafter, signs of degeneration occurred in a gradual process, involving first the most anterior motoneurons and probably proceeding posterior in a zonal pattern. A clear reduction in motoneuron size was noted. The largest cell body detected was smaller than the control. Nuclei were rounded and central. Nissl substance appeared granular and was dispersed over the cytoplasm, and the α -motoneurons were of normal electron density. At 8 weeks, three zones were observed in the ventral horn. The anterior zone was the most affected and showed intensely basophilic shrunken motoneurons. Nearly all nuclei were centrally located, but were irregular in outline. ②Transection experiment： one week after ventral root transection, nuclei were slightly eccentric and irregular in outline, but of normal size. Nucleolar vacuolation was observed in several neurons, and the ultrastructure of the chromatolytic Nissl bodies （NBs） showed disorganized arrangement of rough endoplasmic reticulum （rER） cisternae. The motoneuron cell bodies were of regular shape and size at week 4. Nuclei returned to their normal central location and contour. Many lipofuscin granules and lysosomes were observed in the motoneuron cytoplasm, α-motoneurons appeared to have normal cell bodies; the nuclei were perfectly round, but slightly enlarged with enlarged nucleoli at week 8. There was almost complete recovery of the α-motoneurons. CONCLUSION： α-motoneurons of the C8 spinal segment can survive in the right ventral root in rats after transection at the right ventral rootlets junction to the dorsal rootlets, α-motoneurons of the C8 spinal segment in rats can survive for 4 weeks after avulsion injury. Thereafter, signs of degeneration occur, and the degenerative process proceeds in a zonal pattern.

Common iliac artery occlusion with small intestinal transection caused by blunt abdominal trauma: A case report and review of the literature

BACKGROUND Most major abdominal vascular injuries are caused by penetrating injuries.A common iliac artery occlusion caused by blunt force trauma is rare,and very few cases have been reported.Because of this low incidence,atypical symptoms,and frequent association with other severe injuries,the proper diagnosis tends to be missed or delayed.The gold standard for diagnosis is angiography,and treatment remains a challenge.CASE SUMMARY We report here the unusual case of a common iliac artery occlusion caused by blunt abdominal compressive trauma,with transection of the small intestine.At presentation,the patient(a 56-year-old man)complained of pain and numbness in the left lower extremity and severe pain in the whole abdomen.Physical examination showed total abdominal tenderness with evidence of peritoneal irritation.The left lower limb was pulseless and cold.Abdominal computed tomography examination revealed digestive tract perforation,and abdominal computed tomography angiography showed left common iliac artery occlusion.The patient was treated successfully by anastomosis of the intestine,percutaneous transluminal angioplasty,and stenting.The patient was followed for more than 11 mo after the operation and showed a good recovery.CONCLUSION Patients with abdominal trauma should be suspected of having major vascular injury.Individualized treatment strategies are needed for this condition.

Transection Type, Vesico-Vaginal Fistula Surgery

The objective of the study was to report the results of the surgery of the Vesico-vaginal fistula (VVF) transection types at CHU Conakry. Methods: This was a prospective descriptive study that focused on 64 patients operated for VVF transection type at the Urology department of CHU Conakry between January 2013 and December 2015. Four types of transection were defined according to the state of the urethra and vagina, the size of the fistula, the peri-fistulous tissue and associated lesions. The variables studied were the proportion of transection, age, the type of transection, the number of previous cures, the operative technique, the complications and the results after a follow-up of 3 months. Results: Transection accounted for 47.05% of the obstetric fistulas. The average age was 25.18 years old (14-43 years old). This was a Type I transection (11 cases), type II (27 cases), type III (19 cases) and type IV (7 cases). The surgical approach was vaginal in 64 cases. Fistulorraphy with a confection of a new cervix and cervico-urethral anastomosis was conducted in 19 patients, combined with bladder flap urethroplasty (30 patients) or vaginal flap (15 others). We recorded healing in 37 cases. Conclusion: Transection type VVF is a severe VVF. The preferential surgical approach was vaginal. Technical difficulties were related to associate lesions and the continence system affected.

Brain-derived neurotrophic factor and neural plasticity in a rat model of spinal cord transection

The present study employed a rat model of T10 spinal cord transection. Western blot analyses revealed increased brain-dedved neurotrophic factor （BDNF） expression in spinal cord segments caudal to the transection site following injection of replication incompetent herpes simplex virus vector （HSV-BDNF） into the subarachnoid space. In addition, hindlimb locomotor functions were improved. In contrast, BDNF levels decreased following treatment with replication defective herpes simplex virus vector construct small interference BDNF （HSV-siBDNF）. Moreover, hindlimb locomotor functions gradually worsened. Compared with the replication incompetent herpes simplex virus vector control group, extracellular signal regulated kinasel/2 expression increased in the HSV-BDNF group on days 14 and 28 after spinal cord transection, but expression was reduced in the HSV-siBDNF group. These results suggested that BDNF plays an important role in neural plasticity via extracellular signal regulated kinasel/2 signaling pathway in a rat model of adult spina cord transection.

Complete Cervico-Uretral Transections: A Vesicovaginal Fistula Not Like the Other

Introduction: Complete cervico-urethral transection is a vesicovaginal fistula characterized by total disinsertion of the urethra from the bladder. It is a fistula of the cervico-urethral intersection threatening the mechanism of continence. The aim of this study was to describe the epidemiological and therapeutic aspects of this type of fistula. Patients and Methods: This was a descriptive retrospective study on patients who have had surgery for cervico-urethral transection from June 01, 2012 to June 01, 2015. Results: Cervico-urethral transections (n = 76) accounted for 33.77% of all urogenital fistulas admitted to our department of surgery during the study period. The average age was 25.02 ± 8, 6 years. Married patients accounted for 85.58%, 72.36% had not received any classical education. Fistulas less than one year old made up 56.58% of cases, associated lesions were perineal tears 25.0%, vaginal sclerosis, 21.05%, vaginal straps, 13.15%, rectovaginal fistula, 2.63% and the shortness of the urethra less than 2.5 cm in 42.10% of cases. All surgeries were performed vaginally with a 98.68% fistula closure rate and an average of 1.68 surgeries per patient. After closure of the fistula, 10.67% of patients presented a residual urinary incontinence. Conclusion: Complete cervico-urethral transection is a frequent vesicovaginal fistula. She sometimes exposes to urinary incontinence after closing the fistula. The results of his surgery are often good at the cost of multiple intervention.

Traumatic transection of main stem bronchus with unexpected clinicalpresentation- A case report

Tracheobronchial injury is very challenging in diagnosis and treatment. Highly suspicious airway injury and early diagnosis is recommended. We present a case of 39 years-old woman suffering from acute respiratory failure with bilateral hemo-pneumothorax and diffuse subcutaneous emphysema initially. She weaned from ventilator a few days later, but dyspnea recurred due to delayed diagnosis of complete disruption of right main bronchus. However, the image study was incompatible with clinical findings. It showed collapse of left lower lung and hyperinflation of right lung, instead of right pneumothorax or fallen-lung sign. Under the assistance of veno-venous extracorporeal membrane oxygenation, primary repair of right main bronchial injury was performed successfully. Finally, she recovered well uneventfully. In tracheobronchial injury, early diagnosis is a positive prognostic factor. The other important point is primary repair, instead of lobectomy or pneumonectomy.

Interactive hepatic parenchymal transection simulation with haptic feedback

Background Liver resection involves surgical removal of a portion of the liver.It is used to treat liver tumors and liver injuries.The complexity and high-risk nature of this surgery prevents novice doctors from practicing it on real patients.Virtual surgery simulation was developed to simulate surgical procedures to enable medical professionals to be trained without requiring a patient,a cadaver,or an animal.Therefore,there is a strong need for the development of a liver resection surgery simulation system.We propose a real-time simulation system that provides realistic visual and tactile feedback for hepatic parenchymal transection.Methods The tetrahedron structure and cluster-based shape matching are used for physical model construction,topology update of a three-dimensional liver model soft deformation simulation,and haptic rendering acceleration.During the liver parenchyma separation simulation,a tetrahedral mesh is used for surface triangle subdivision and surface generation of the surgical wound.The shape-matching cluster is separated via component detection on an undirected graph constructed using the tetrahedral mesh.Results In our system,cluster-based shape matching is implemented on a GPU,whereas haptic rendering and topology updates are implemented on a CPU.Experimental results show that haptic rendering can be performed at a high frequency(>900Hz),whereas mesh skinning and graphics rendering can be performed at 45fps.The topology update can be executed at an interactive rate(>10Hz)on a single CPU thread.Conclusions We propose an interactive hepatic parenchymal transection simulation method based on a tetrahedral structure.The tetrahedral mesh simultaneously supports physical model construction,topology update,and haptic rendering acceleration.

Axotomy induces damage to glial cells remote from the transection site in the peripheral nervous system

Traumatic cerebral or spinal cord injury induced by military,traffic,and sports accidents,falls or environmental and anthropogenic catastrophes are among main causes of people mortality and disability,especially in young and middle age men（Kobeissy,2015）.Axon transection,or axotomy,occurs in wounds and during surgery.