Interaction between Schwann cells and other cells during repair of peripheral nerve injury

Peripheral nerve injury(PNI)is common and,unlike damage to the central nervous system injured nerves can effectively regenerate depending on the location and severity of injury.Peripheral myelinating glia,Schwann cells(SCs),interact with various cells in and around the injury site and are important for debris elimination,repair,and nerve regeneration.Following PNI,Wallerian degeneration of the distal stump is rapidly initiated by degeneration of damaged axons followed by morphologic changes in SCs and the recruitment of circulating macrophages.Interaction with fibroblasts from the injured nerve microenvironment also plays a role in nerve repair.The replication and migration of injury-induced dedifferentiated SCs are also important in repairing the nerve.In particular,SC migration stimulates axonal regeneration and subsequent myelination of regenerated nerve fibers.This mobility increases SC interactions with other cells in the nerve and the exogenous environment,which influence SC behavior post-injury.Following PNI,SCs directly and indirectly interact with other SCs,fibroblasts,and macrophages.In addition,the inter-and intracellular mechanisms that underlie morphological and functional changes in SCs following PNI still require further research to explain known phenomena and less understood cell-specific roles in the repair of the injured peripheral nerve.This review provides a basic assessment of SC function post-PNI,as well as a more comprehensive evaluation of the literature concerning the SC interactions with macrophages and fibroblasts that can influence SC behavior and,ultimately,repair of the injured nerve.

Trigger finger at the wrist caused by an intramuscular lipoma within the carpal tunnel:A case report

BACKGROUND Trigger finger at the wrist,which occurs with finger movement,is an uncommon presentation.Few reports describing cases of trigger finger at the wrist have been published.Thus,we present a case of an intramuscular lipoma arising from an anomalous flexor digitorum muscle belly in a 48-year-old female patient causing painful finger triggering at the wrist and carpal tunnel syndrome(CTS).CASE SUMMARY A 48-year-old woman with complaints of a catching sensation during wrist motion and a progressive tingling sensation on the palmar aspect of the right hand for approximately 2 years was referred to our hospital.Triggering of the index to middle finger was evident with a palpable and audible clunk over the carpal tunnel during passive motion.Tinel’s sign was positive over the carpal tunnel of the right wrist with a positive Phalen’s test.Nerve conduction studies of the median nerve demonstrated a right CTS.Ultrasound examination revealed a 2.5 cm×2.0 cm subcutaneous hyperechoic mass with no obvious blood flow at the wrist of the right arm.Surgical excision of the tumor and muscle mass led to a resolution of the patient’s symptoms,and any triggering or discomfort disappeared.The patient has had no evidence of recurrence at more than 1 year of follow-up.CONCLUSION Triggering of the fingers at the wrist is rare. It must be noted that there are manypossible causes and types of triggering or clicking around the wrist. Accuratediagnosis is mandatory to avoid inaccurate treatment of patients with triggerwrist. During the diagnosis and treatment of CTS, attention should be paid to thevariation of tendon tissue in the carpal tunnel, to avoid only focusing on therelease of transverse carpal ligament and ignoring the removal of anomalousmuscle belly.