Hi I’m Dr Simon Freilich Consultant in Clinical Neurophysiology and in this video I will talk
about Benign Fasciculation Syndrome or BFS for short.
Fasciculation’s are involuntary muscle twitches that can occur in both healthy people, and
those with a wide variety of diseases.
It’s difficult to say just how common this condition is, but it is not rare, and it is well
described amongst health professionals.
It is important to state that BFS is a diagnosis of exclusion i.e. one needs to investigate
other potential causes before making this diagnosis.
However, there are a number of clinical pointers towards BFS rather than being as a result
of an underlying pathological condition.
BFS tends to affect the muscles in the lower legs, hands and eyelids.
It can even cause twitching in the tongue and in the ear muscles causing a beating sound
to be felt.
The twitches tend to occur periodically, with some periods where the condition is more active
than others and also tends to flit between muscle regions.
In this video clip you can see a patient’s muscle twitching autonomously.
It is quite irregular and arrhythmic and is occurring in one of the typical muscles to
be affected in the hand.
They can also be associated with cramps, myalgia, tingling, fatigue, anxiety and a sensation
of something being stuck in the throat called ‘Globus Pharyngis’.
The twitches may be exacerbated by tiredness and stress and can be partially interrupted
by actively moving the muscles involved.
The most important features that needs to be checked is that there should be no muscle
weakness or wasting.
If there is, it would argue against BFS and the fasciculation’s would likely be secondary
to another condition.
It is generally accepted that Fasciculation’s are due to an over excitability of the nerves
innervating the muscles.
However, because the nervous system is both highly complex and involves long distances,
it has proven difficult to provide categorical answers as to where exactly in the nervous
system they originate.
There is evidence of both spinal cord and peripheral nerve origins to the fasciculations
in BFS.
More recently, thanks to pioneers such as Prof Hugh Bostock, we have been better able
to study nerve excitability.
Individual ion channel dysfunctions such as HCN which may play a role in inducing over
excitability of the nerves.
Other conditions that can be associated with fasciculations include:
Radiculpathies and Neuropathies which can lead to nerve damage and dysfunction.
Neuromuscular Junction Disturbances can also increase the probabilities of spontaneous
contractions, Metabolic causes such as Hyperthyroidism and
Hyperparathyroidism can have primary or secondary effects.
Electrolyte disturbances such as having raised Potassium or low Magnesium and Calcium levels
Vitamin D Deficiency can have secondary impact on calcium levels.
Stimulants such as drinking too much Caffeine can cause this.
Medications that enhance the sympathetic nervous system with Adrenalin like substances such
as Epinephrine nasal sprays or Amphetamines.
Anti-cholinergic agents such as Ipratroprium and Tiotropium that are used in Asthma, or
Trihexyphenydate that may be used in Parkinson’s Disease,
Diuretics used in Heart failure and ACE-Inhibitors in Hypertension can alter potassium levels.
Statins for raised cholesterol, Isoniazid in TB, Opiates and Opiate withdrawal and Corticosteriods
are all well described.
Auto-immune conditions such as Isaacs Syndrome and certain Spinocerbellar Atrophy syndromes
are very rare causes of fasciculation’s.
Of course, what commonly worries most patients and their physicians is potential Motor Neurone
Disease.
Motor neurone disease is progressive and is associated with clinical weakness and wasting
of the muscles.
In addition, fasciculation’s in MND tend to be persistent, spread and are found in
adjacent areas rather than flitting between disparate areas.
What is very important in these situations is Neurophysiology studies using EMG to look
for evidence of underlying denervation which may be sub-clinical.
You can see examples of fibrillations and fasciculation’s in the I-Cards above.
The nature of the fasciculation’s can also be helpful such as double fasciculation’s
though complex wave forms do not appear to be as diagnostic as previously thought.
Ultimately, time is the greatest discriminator and once past the 4 or 5 year mark without
additional signs, BFS is a secure diagnosis.
So in terms of diagnosis – a good clinical history looking for the features listed above,
going through all relevant medications and a thorough clinical examination are required
to exclude alternative and more serious causes.
Blood tests will be necessary to check electrolyte and metabolic disturbances and where necessary
for auto-immune conditions.
And of course Neurophysiology studies with NCS Tests and EMG are important screening tools.
In time Nerve excitability studies may become more mainstream as we continue to learn more
about this condition.
Treatment Is symptomatic and should be holisitic.
So if sleep deprivation and stress are contributory causes these will need evaluation and will
need to be addressed.
Stress and anxiety are potent activators of the Sympathetic Nervous System which drives
the flight and fright response and nerve hyperexcitability.
Stress management techniques can be helpful to ameliorate this.
Caffeine and other stimulants should be avoided.
Some patients can have this as a result of sleep apnoea which may need specific treatment.
Any electrolyte disturbances or vitamin deficiencies will need screening and correction and any
exacerbating medications should be discontinued, where possible.
There are certain medications such as Carbamazepine, Propanolol and Verapamil which can help, though
the benefits are often less than satisfactory and this condition tends to wax and wane anyway.
There doesn’t appear to be any long-term health consequences of having this condition.
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