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Definition of tremor: "A rhythmical oscillation of a body part "
6 Main Types
(More detailed information can be found below)
Physiologic Tremor (frequency 10-12 Hz)
This is a common tremor. Almost everyone
has experienced this tremor. There is likely a lowered threshold for this type of tremor in certain families. It is seen when it is triggered by anxiety, fever, hyperthyroidism, physical
exhaustion, low blood sugar. Some medications and some chemicals (e.g. theophyline, caffeine, alchohol withdrawal) will accentuate physiologic tremor.
Treatment:
Often no treatment is necessary other than
reassurance once the diagnosis is made. Triggering factors should be removed (eg. reduce caffeine intake, get adequate sleep and avoid going hungry). If severe enough medications,
including B-blockers or anxiolytics, can be prescribed.
Essential Tremor (frequency 4-12 Hz)
This is the most common movement
disorder. It has been reported to affect 3% of the population. It is an inherited condition and the trait for this tremor can be passed from generation to generation. Fifty percent
of children of an affected parent will inherit the tendency to get the tremor (autosomal dominant inheritance). The tremor will usually affect both sides of the body but may be
asymmetric. The tremor severity slowly worsens with age (frequency slows, amplitude increases) with some stable phases occasionally lasting years.
The tremor may be very disabling with 15% of patients having to retire prematurely due to the tremor.
The tremor most often affects the
hands, but may affect arms, legs (~30%), voice, and/or head. This tremor typically stops with rest or relaxation of the arms. It is more apparent when the patient holds their arms out
straight (posturing) or when they are performing activities (intention) such as drinking soup with a spoon, or writing.
It is worse when triggered by anxiety,
fever, hyperthyroidism, physical exhaustion or low blood sugar. Some medications and some chemicals (e.g. theophyline, caffeine, alchohol withdrawal) will accentuate essential tremor.
Treatment:
Often no treatment is necessary other
than reassurance once the diagnosis is made. Some counseling may be required in younger
patients regarding career choices. Triggering factors should be removed (eg. reduce caffeine intake). If severe enough medications can be prescribed.
Medication options:
1) Propranolol on an as needed basis, such as prior to stressful events (works within a half hour and usually lasts 2-3 hrs).
2) Daily Propranolol (doses > 120 mgs/day are usually needed when used chronically). Note this is not a safe option in asthmatics.
3) Daily Primidone.
4) Daily Propranolol and Primidone combined
5) Daily Topiramate (Topamax)
6) If the above are ineffective
gabapentin, diamox, pregabalin, clonidine, amantidine, clonazepam, clozapine have been suggested as other options.
Surgical Options:
See (Review article tremor and other hyperkinetic Movements 2017) for treatment algorithm.
1) The standard surgical treatment is to implant a
deep brain stimulator (DBS) which is a small electrode implanted into thalamus that is connected to a programmable transmitter under the chest wall, like a pacemaker. By electrically
interfering with the natural firing pattern of the nerve cells in this area the tremor (VIM nucleus) is electrically suppressed. The goal is to not cause any permanent lesion in the brain. This, if
successful, will stop the tremor on the opposite side of the body. There are, as with any surgery, possible side effects that need to be discussed and considered. Risks increase with
bilateral procedures but these remain safer than techniques that lesion the brain.
2)
Steriotactic radio frequency thalmotomy
is a procedure that surgically lesions (destroys) a very small area deep within the brain that causes the tremor (the thalamus). This, if successful, will stop the tremor on the opposite side of the body. There are, as with any surgery, possible side effects that need to be discussed and considered. This will only target treating the tremor on the opposite side of the body. Doing this procedure on both sides can risk significant speech impairment. Due to a higher risk of permanent neurologic side effects, this procedure is not as commonly recommended as it was in the past.
3)
High intensity focussed ultrasound (HIFU) thalmotomy
is a more recent technique to non surgically destroy brain pathways in an attempt to improve function of the basal ganglia and associated structures. This is a technique that is still undergoing investigation. MMRI scanning prior to the procedure helps identify the correct location of the target in the patient's brain. Although bilateral procedures in the past directed at the VIM nucleus of the thalamus were associated with a risk of increased side effects, there are newer targets being identified (cerebellothalamic tract) that may make bilateral treatments safer. Long term outcomes > 1 year are not yet published (as of 2017). Side effects reported in the NEJM in 2016 included 36% incidence of gait disturbance and 38% risk of sensory changes on the treated side. The procedure was approved by the FDA in July 2006. See (Review article tremor and other hyperkinetic
Movements 2017)
4)
Gamma knife (radio surgery) thalmotomy
is also a procedure that destroys a very localized area in the brain by applying many small radiation beams into one focussed spot. This procedure can be done without the need of any incisions. It also doesn't take as long to complete. The experience with this technique is more limited and remains under investigation.
Basal Ganglia Tremor (Parkinsonism) (frequency 4-5 Hz)
This is the type of tremor seen as part of the features of Parkinson's Disease and other illnesses damaging the basal ganglia. The basal ganglia is a group of nerve cells (ganglia) deep within the brain (at the base of the brain). It is most
evident at rest and unlike essential tremor tends to improve with posturing or action. Approximately 30% of patients with Parkinson's Disease can have an associated action tremor (6-12
Hz). These tremors start on one side and will usually progress to the other side within 2 years.
Treatment:
Medication options:
The medications typically used to
treat Parkinson's Disease often suppress tremor quite successfully. Despite this some patients will suffer from medically unresponsive (refractory) tremor.
The main medications used include but are not limited to; levodopa, dopamine agonists, amantadine, and anticholinergics.
When this type of tremor occurs as the
result of other diseases which affect the basal ganglia (eg. stroke) it is less responsive to medication.
Surgical Options:
- 1)The standard surgical treatment is to implant a deep brain stimulator (DBS) which is a small electrode implanted
into the brain that is connected to a programmable transmitter under the chest wall, like a pacemaker. By electrically interfering with the natural firing pattern of the nerve cells in this
area is electrically suppressed. The goal is to not cause any permanent lesion in the brain. This, if successful, will stop the
tremor on the opposite side of the body. The targets for Parkinson's disease include the subthalamic nucleus and the globus pallidus interna. There are, as with any surgery, possible side effects that need to be discussed and considered. Risks increase with bilateral procedures but these remain safer than techniques that lesion the brain.
-
- 2) Steriotactic radio frequency thalmotomy
is a procedure that surgically lesions (destroys) a very small area deep within the brain that causes the tremor (the thalamus). This, if successful, will stop the tremor on the opposite side of the body. There are, as with any surgery, possible side effects that need to be discussed and considered. This will only target treating the tremor on the opposite side of the body. This will not help the rigidity and slowness of movement that is seen in Parkinson's disease.
- Doing this procedure on both sides can risk significant speech impairment. Due to a higher risk of permanent neurologic
side effects, this procedure is not as commonly recommended as it was in the past.
- 3) High intensity focussed ultrasound (HIFU) thalmotomy
is a more recent technique to non surgically destroy brain pathways in an attempt to improve function of the basal ganglia and associated structures. This is a technique that is still undergoing investigation for a possible role in PArkinson's disease.
Cerebellar Tremor
(frequency 3-4 Hz)
Tremors can result from damage to the cerebellum. They can be associated with a variety of types of ataxia,
The cerebellum is a structure attached to the back of the brain stem, inside the skull. It is made up of two halves, the hemispheres. The main function of the cerebellum is to
coordinate motor activity. When one hemisphere is damaged there is a loss of coordination on the same side of the body.
Tremors can result by damage to the
cerebellar outflow pathways. These true rhythmic tremors will be absent at rest, and maximal with activity. Some cerebellar tremors callled Holme's tremor are more obvious with
posturing and at rest ("rubral" or red nucleus tremors). Cerebellar tremors due to
lesions of the hemispheres of the cerebellum tend to be more irregular, erratic and non rhythmic "tremors" with action.
Treatment:
Cerebellar tremors are very difficult
to treat. Weighting the arms by placing something heavy around the wrists can help. Surgical treatment results are not as good in general as with essential tremor but can still be
considered for rhythmic tremors. This surgery does not help the poor coordination (ataxia) associated with cerebellar lesion.
Medication Options:
Although no medications work well; Topamax, Isoniazid, Clonazepam, Tegretol, Amantadine and Buspirone have been suggested.
Dystonic Tremor
Not infrequently dystonic movements
can be associated with a rhythmic oscillation. This combination of movements would be called Dystonic Tremor. The main treatment approach would be to treat the dystonia.
Functional Tremor
- The exact way this type of tremor develops is still under investigation. There are cases where stress is clearly a contributor but
often no trigger is identified.
It can affect any body part and patients with this type of tremor can take years and undergo extensive diagnostic testing without being advised of the cause of their tremor. Techniques during the exam can result in marked or complete brief resolution of the tremor allowing the diagnosis to become more clearly established then allowing successful treatment programs to be set up. See the page on Functional Movement Disorders.
Others:
Some tremors persist at rest, with
posture, and with action. These tremors are usually associated with medication side effects, hepatic failure (eg. Wilson's Disease), or due to functional disorders.
Other rare conditions that can mimic tremors are:
Myorhythmia, Rhythmic Myoclonus, Clonus. Task specific tremors
Epilepsia Partialis Continuans
Head bobbing with 3rd ventricular cysts
Orthostatic Tremor - is a tremor that only occurs with standing and mainly affects the legs and causes those affected to feel like their legs will give way.
Unspecified tremor
is a term some specialists use when the features of the tremor do not clearly fit one of the above categories and individuals presenting with this type are usually watched over time until the diagnosis becomes more clearly established.
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