Neural strain

Neural strain resulting from biomechanical causes can cause profound metabolic changes in the affected tissue. Injury can result from tensile, compressive, or shear stress or as a combination of stresses.

Tension
In animal models, stretching or tension of nerves results in substantially reduced blood flow. Tension impairs nerve regeneration.

Tethered cord syndrome
Tethered cord syndrome, a condition where tissue attachments limit the movement of the spinal cord within the spinal column, is associated with impaired glucose metabolism in spinal cord tissue, changes in the reduction/oxidation ratio of cytochrome oxidase. and reduced ATP production. Energy loss due to neural membrane stretching contributes to leakage of sodium, potassium and calcium.

A study of energy cost of walking in adolescents with tethered cord, as measured by oxygen uptake, found that “energy cost per metre during walking at preferred speed and physical strain were higher than in peers without disability.”

People with tethered cord syndrome have reduced blood flow to the spinal cord.

“Traction on the caudal cord results in decreased blood flow causing metabolic derangements that culminate in motor, sensory, and urinary neurological deficits. The untethering operation restores blood flow and reverses the clinical picture in most symptomatic cases.”

In a study of five children undergoing surgery for tethered cord syndrome group, spinal cord blood flow prior to untethering was a mean of 12.6 ml/min per 100 g of tissue. It increased in all cases after release to a mean of 29.4 ml/min per 100 g of tissue.

Compression
Compression of nerves can result in changes in microcirculation and ischemia, changes in vascular permeability, edema, axonal damage, and has been associated with demyelination.

Prologned compression can result in inflammation and activation of endoneurial fibroblasts, mast cells, and macrophages.

Diagnoses
Diagnoses associated with tension, compressive and shear stress:
 * Tethered cord syndrome
 * Cranial settling
 * Craniocervical instability
 * Cervical stenosis
 * Nerve compression syndrome

ME/CFS
In a study of neuromuscular strain in ME/CFS, 60 people with ME/CFS and 20 healthy controls randomly were assigned to undergo a neuromuscular strain maneuver or sham maneuver. Those with ME/CFS in the strain condition group had significantly increased symptoms for up to 24 hours.