Re:Re:Nerve stretching: a history of tension

[문형철]

beyond reason

neural mobilization 동영상을 먼저 보고 ... 클릭클릭

선우정골요법은 이 관점에서 최고의 테크닉!!

Nerve stretching: a history of tension

Stretch injuries are among the most devastating forms of peripheral nerve injury; unfortunately, the scientific understanding of nerve biomechanics is widely and impressively conflicting. Experimental models are unique and disparate, victim to different testing conditions, and thus yield gulfs between conclusions. The details of the divergent reports on nerve biomechanics are essential for critical appraisal as we try to understand clinical stretch injuries in light of research evidence. These conflicts preclude broad conclusion, but they highlight a duality in thought on nerve stretch and, within the details, some agreement exists. To synthesize trends in nerve stretch understanding, the author describes the literature since its introduction in the 19th century. Research has paralleled clinical inquiry, so nerve research can be divided into epochs based largely on clinical or scientific technique. The first epoch revolves around therapeutic nerve stretching—a procedure known as neurectasy—in the late 19th century. The second epoch involves studies of nerves repaired under tension in the early 20th century, often the result of war. The third epoch occurs later in the 20th century and is notable for increasing scientific refinement and disagreement. A fourth epoch of research from the 21st century is just dawning. More than 150 years of research has demonstrated a stable and inherent duality: the terribly destructive impact of stretch injuries, as well as the therapeutic benefits from nerve stretching. Yet, despite significant study, the precise border between safe and damaging stretch remains an enigma.

Current Research Stretching for Nerve Injury 

The vast bulk of research on nerve stretch has not addressed the relatively common challenge of traumatic/ high-speed stretch injuries to nerves. The challenge has been that, other than the attempts by Denny-Brown,16 no research has reproduced the neuroma-in-continuity injuries seen from nerve stretch injuries. 

Nearly all research on peripheral nerve injury and regeneration has focused on standardized crush or transection injuries. One recent attempt, however, has added nerve tension to create a more “clinically relevant experimental model.”2,3 With static traction applied to a crush injury in a rat model, worsened outcomes were reported, indicative that traction creates an independent pathophysiological injury. Our group has been working on a standardized experimental model for recreating the violent trauma from rapid-stretch injury53 that reproduces long-zone mechanical disruption. 

Stretching for Nerve Repair 

Severe nerve injuries often lead to a segmental deficiency of nerve (the “nerve gap”). This is compounded by neuroma formation on the proximal stump, which needs to be cut back to typical fascicular structure. Although grafting autologous nerves to fill the gap can produce recovery, grafted nerves produce worse results than nerves repaired by direct suture repair.31 

Serially stretching the proximal end to elongate it toward the distal end has been proposed as a solution. First investigated using inflatable tissue expanders, successful elongation of intact rat sciatic nerves beyond 50% length was achieved without retraction when the expander was removed.43 However, nerve conduction velocity decreased 40%–60%, which worsened with greater stretch elongation. Endo and Nakayama18 noted segmental demyelination but intact axonal processes. 

More recent techniques for therapeutic nerve elongation, such as progressive-stretch devices,23 are attractive because tissue expanders create compressive injury. Ochiai’s group has suggested that progressive stretch applied to the proximal stump produces elongation of regenerative nerves45,46 and that repair of a nerve gap after stretch-growth provides better electrophysiological and histological results than grafting.55 Similarly, Shah and investigators confirmed the finding that tension on the cut end of a proximal stump produced stretch-growth of the nerve.