Nervous System and Metameres: The Key to Understanding Fibromyalgia

To understand fibromyalgia in its essence, it is necessary to familiarize oneself with a fundamental concept of neuroanatomy: the metamere. It is a functional unit of the nervous system that represents the key to interpreting many of the seemingly disconnected symptoms of fibromyalgia syndrome.

What is a metamere?

A metamere is a functional section of the body, governed by a segment of the spinal cord. Each metamere connects, through nerve pathways, the portion of skin (dermatome), muscles (myotome), bones and joints (sclerotome), and internal organs (viscerotome) corresponding to that vertebral level.

This means that an alteration in one component of the metamere can reflect on the others. An organ in distress can cause muscle pain in the corresponding area; a muscle contraction can alter skin sensitivity; a visceral disorder can manifest as joint stiffness.

The metamere overload

In fibromyalgia, the metameres are in a state of bioelectric overload. The sensory stimuli that reach the spinal cord from the skin, muscles, and organs are excessive and create short circuits within the metamere. The nervous system, unable to manage this excess of information, produces abnormal responses:

• Persistent muscle contractions
• Alterations in skin sensitivity
• Dysfunctions of associated internal organs
• Referred pain in areas seemingly distant from the cause

Why is the pain widespread?

The metameric nature of fibromyalgia explains why the pain is so widespread and variable. When multiple metameres are involved — and in full-blown fibromyalgia, almost all are — the symptoms are distributed throughout the body, creating that picture of generalized pain that characterizes the syndrome.

The role of the autonomic nervous system

Each metamere is also home to fibers of the autonomic nervous system (sympathetic), which regulates involuntary functions such as local blood circulation, sweating, vascular tone, and the motility of internal organs. When the metamere is overloaded, these functions are also altered, explaining symptoms such as cold hands, abnormal sweating, digestive disorders, and palpitations.

An integrated view

The metameric perspective offers a fundamental advantage: it allows us to understand how seemingly disconnected symptoms — neck pain, gastroesophageal reflux, tingling in the hands — can have a common origin in the overload of one or more metameres. This understanding paves the way for targeted and effective therapeutic interventions that address the cause and not just the individual symptoms.