Idiopathic intracranial hypertension (IICH) is characterized by high intracranial pressure (ICP, pressure in the brain). In addition, patients often report pain in the back, neck, arms and legs caused by the compression of nerves in the spinal cord by the cerebrospinal fluid (CSF, the liquid that circulates in the central nervous system).
These widespread pain symptoms are incredibly similar to those experienced by patients with the chronic pain disorders fibromyalgia (FM) and chronic fatigue syndrome (CFS).
“While IICH is characterized by a significant increase in cerebrospinal pressure [pressure caused by the cerebrospinal fluid, CSP], FM and CFS may be the result of intermittent and/or mild chronic increased CSP,” the researchers noted.
This review focused on gathering and comparing data from previous studies regarding the signs and symptoms of IICH, FM, and CFS to explore whether high CSP could be the link between the three chronic pain disorders.
Data revealed that high ICP is associated with headaches, fatigue, cognitive impairment, loss of gray matter, cranial nerve damage (e.g., impaired smell and vision) and olfactory problems (e.g., sinusitis, nonallergic rhinitis) in all three disorders.
Of note, gray matter refers to areas of the central nervous system (brain, brainstem, and cerebellum) made up of neuron cell bodies. Cranial nerves are nerves that emerge directly from the brain, such as the olfactory and optic nerve.
On the other hand, increased pressure in the spinal cord led to widespread pain, muscle weakness in the arms and legs, difficulty walking (ataxia), bladder, and bowel problems.
Moreover, they also found that IICH, FM and CFS are more prevalent in women than men and are frequently associated with other medical conditions, including obesity and Ehlers-Danlos syndrome, a genetic disorder that weakens connective tissues (skin, bones, blood vessels and other organs).
Finally, researchers noticed the three disorders also were associated with over-activation of the sympathetic nervous system.
“The sympathetic nervous system prepares the body to fight or flight. [Over-activation] symptoms [may] include (…) digestive problems (slower gastric emptying), constipation (slower bowel peristalsis), superficial breathing, tachycardia [faster heartbeat], postural hypotension [blood pressure drop after standing], anxiety, night sweats, poor sleep quality, obstructive sleep apnea, and fatigue,” the investigators wrote.
Altogether, these findings indicate that “IICH, FM, and CFS share very similar characteristics and are probably caused by the same underlying disorder of increased CSP. [F]uture research should probably focus on therapeutic strategies to lower CSF pressure [in these patients],” they concluded.