Benign fasciculation syndrome

Template:Short description Template:Infobox medical condition (new) Benign fasciculation syndrome (BFS) is characterized by fasciculation (twitching) of voluntary muscles in the body.<ref name= Blackman2019>Template:Cite journal</ref> The twitching can occur in any voluntary muscle group but is most common in the eyelids, arms, hands, fingers, legs, and feet. The tongue can also be affected. The twitching may be occasional to continuous.<ref name= Walter2015/> BFS must be distinguished from other conditions that include muscle twitches.

Signs and symptoms

The main symptom of benign fasciculation syndrome is focal or widespread involuntary muscle activity (fasciculation).<ref name= Blackman2019/> The benign twitches usually have a constant location.<ref name= Walter2015>Template:Cite journal</ref>

Other common symptoms are generalized fatigue or weakness, paraesthesia or numbness, and muscle cramping or spasms.<ref name= Blackman2019/> Anxiety and somatic symptom disorders and symptoms are commonly reported.<ref name= Blackman2019/> Muscle stiffness may also be present; if muscle weakness is not also present, and cramps are more severe, the stiffness may be categorized instead as cramp fasciculation syndrome.<ref name= Turner2013/> Cramp fasciculation is a variant of BFS which presents with muscle pain and exercise intolerance.<ref name= Walter2015/><ref name= Carvalho2017/>

Causes

Health anxiety disorder may be a cause among individuals who become concerned they have a motor neuron disease; this persistent concern is a psychiatric condition mostly noted among healthcare professionals and doctors.<ref name= Blackman2019/> An association with anxiety level is established;<ref name= Blackman2019/><ref>Template:Cite journal</ref> BFS is reportedly found among "anxious medical students" and clinicians under the age of 40,<ref name= Turner2013/> and this phenomenon known as "fasciculation anxiety syndrome" is reinforced by access to information on the internet.<ref name= Carvalho2017/>

Fasciculations can be caused<ref name= Carvalho2017/> or worsened by intense and long periods of daily exercise.<ref name= Walter2015/>

BFS can also be caused by long-term use of anticholinergics,<ref name= Carvalho2017/> and fasciculations may be caused by other drug use or exposure to steroids, nicotine, caffeine, alcohol, insecticides and pesticides.<ref name= Walter2015/> Thyroid disease may also cause similar symptoms.<ref name= Turner2013/>

Fasciculations can also be caused by deficiencies of magnesium and/or calcium.<ref name=McDaniels2018>Template:Cite news</ref>

Diagnosis

Benign fasciculation syndrome is a diagnosis of exclusion; that is, other potential causes for the twitching must be ruled out before BFS can be diagnosed. Diagnosis includes blood tests, a neurological exam, and electromyography (EMG).<ref name= Walter2015/>

Another step in diagnosing BFS is checking for clinical weakness or wasting, which are found in more serious conditions.<ref name= Carvalho2017/><ref name= Walter2015/> Lack of clinical weakness along with normal EMG results (in those with only fasciculations) largely eliminates more serious disorders from potential diagnosis.<ref name= Walter2015/><ref name= Turner2013/> In younger people with only lower motor neuron (LMN) fasciculations, no muscle weakness, and no thyroid abnormalities, Turner and Talbot (2013) state that "individuals under 40 years can be reassured without resorting to electromyography (EMG) to avoid the small but highly damaging possibility of false-positives".<ref name= Turner2013/>

According to Kincaid (1997), the diagnosis is made when there is no clinical finding of neurogenic disease; he first reassures patients that no "ominous disease seems to be present", and says, "I suggest that patients like this be followed for a year or longer with clinical and electromyographic exams at about 6-month intervals before one becomes secure in the diagnosis that the fasciculations are truly benign."<ref>Template:Cite journal</ref> Other publications recommend followups for four or five years before ruling the condition benign, although the percentage of individuals who progress to a more serious condition is very low.<ref name= Walter2015/>

Classification

Benign fasciculation syndrome and the variant cramp fasciculation syndrome "can be regarded as part of a larger spectrum of disease that also incorporates acquired auto-immune neuromyotonia.<ref name= Carvalho2017/>

Differential

Other serious diseases that must be distinguished include motor neuron diseases (MND) such as amyotrophic lateral sclerosis (ALS),<ref name= Turner2013/> neuropathy,<ref name=Carvalho2017>Template:Cite journal</ref> and spinal cord diseases.<ref name= Carvalho2017/>

According to Turner and Talbot (2013), "the fasciculations of MND are often abrupt and widespread at onset in an individual previously unaffected by fasciculations in youth. The site of the fasciculations, for example, those in the calves versus abdomen, has not been shown to be discriminatory for a benign disorder. There is conflicting evidence as to whether the character of fasciculations differs neurophysiologically in MND."<ref name= Turner2013>Template:Cite journal</ref> It is "exceptionally rare for patients later diagnosed with ALS to present with fasciculations alone", and ALS is ruled out with a normal EMG and no evidence of muscle wasting.<ref name= Walter2015/>

Treatment

There is support for treating any accompanying anxiety using cognitive behavioral therapy or antidepressants.<ref name= Blackman2019/> Quinine is effective, but not recommended because of the potential for serious side effects.<ref name= Walter2015/> Calcium channel blockers may be effective, although the evidence for their use is weak.<ref name= Walter2015/> There is little evidence supporting other therapies.<ref name= Walter2015/>

In cases caused by magnesium or calcium deficiencies, curing the deficiency through diet or supplementation is effective.<ref name=McDaniels2018/>

Prognosis

The prognosis for those with BFS is good to excellent.<ref name=Brigo2013>Template:Cite journal</ref>

Research

There may be an association between widespread fasciculations or paresthesias with small fiber neuropathy.<ref>Template:Cite journal</ref><ref name=Tzatha2014>Template:Cite journal</ref>

A 2017 study by Neurology.org also found that Benign Fasciculations are common in the general population, occurring in about 70% of healthy individuals and almost never associated with a serious neuromuscular disorder. Of patients that enrolled in a 1, 3, 6, 12 and 24 month study, perceived weakness was reported in 35.3%, 47.1% experienced numbness, 70.6% had tingling, cramps were present in 64.7% and after 24 months, only 5% had their symptoms resolved. Of all the patients, none developed Motor Neuron Disease.<ref>Template:Cite journal</ref>