User:Snake playing a saxaphone/histology of nerve entrapment

Histology [deprecated?]
Nerve entrapment is treated with a decompression rather than a biopsy, so human tissue of nerve entrapment is rare.

The predominant finding is a thinning of myelin in myelinated fibers. This is due to the end stages of demyelination or the early stages of remyelination.

The degree of demyelination can vary within a fascicle and between fascicles.

The histopathological findings in the scarce human tissue samples are consistent with the results found in animal models.

The histopathology changes most in the area under compression.

Increased microvascular permeability is an early indicator of tissue injury. For nerve compression this is the step in the pathophysiology cascade and is detected with the use of Evans blue albumin. This substance is injected before nerve tissue harvested and the spread of this blue dye allows the visual tracking of vascular permeability.

Renaut bodies are seen in histology of compressed nerves although the function of Renaut bodies remains unclear.

[You can keep this if you talk about histological changes seen like myelin / axon ratio]

[The thinning myelin image would be nice]

Histological studies are the foundation of assessing structural changes caused by nerve entrapment.

[Mention that data from animal studies is in agreement with human tissue samples] Histological studies of compressed nerve show abnormalities in the compressed region.

Animal models are where the bulk of nerve pathophysiology research has been done. The two most common animal models are rabbits and rats. Studies have been done acute nerve compression, chronic nerve compression , nerve stretch , nerve adhesions , repetitive compression , etc.

Human studies are the best model for nerve entrapment but suffers from lack of availability of nerve tissue. Nerve biopsies aren't generally used to study nerve entrapment because a biopsy will result in permanent nerve dysfunction. Access to human tissue generally comes from cadavers or a sensory nerve like the sural nerve, LFCN, ACN when the nerve is resected anyway as a medical treatment. Due to the poor availability of human nerve tissue, it is not possible to study a progression of nerve entrapment but rather the available tissue acts as a snapshot at that specific moment in the disease progression that can be correlated to animal models.

Human nerve tissue under various stages of compression is generally limited to case studies. Examples of some cases studies are the sural nerve, radial nerve, anterior cutaneous abdominal nerve, and lateral femoral cutaneous nerve.

[Human studies are hard because biopsies will mean a Sunderland 5 injury]

[this section is probably important to show what the findings of resected nerves are]

[meralgia paresthetica]

In a study on resected LFCN nerves, the major findings where: multi-focal fiber loss, reduced fiber density, selective loss of large myelinated fibers, perineurial thickening, subperineurial edema, and renaut bodies. These features were not seen in the control nerves.

[sural nerve biopsy]

[radial nerve]

[anterior cutaneous abdominal nerve]

In a study on ACNES, resected anteriour cutaneous abdominal nerves were examined histopathologically for evidence of inflammation or infection as an alternative cause. No evidence of either of those disease process was found in any patients.