Essential tremor usually affects the upper extremities and the hands, but it may also involve head, lower extremities, tongue and voice. Patients usually complain of heir handwriting becoming sloppier, large and irregular. Patients also complain of trouble holding things like screwdriver, a cup of coffee or soup. They may spill things and feel embarrassed about going to eat out. Sometimes writing cheques may be a challenge for these patients.

 Tremor usually affects both sides but initially may be noticed only on one side. It could occur at any age, but more commonly it is seen  in patients above 55 years of age. The intensity of tremor increases with advancing age. This type of tremor is temporarily dampened by g alcohol. The tremor of the hands is usually of medium frequency ( 5- 8Hz). It is usually seen when patients have their arms outstretched in front of their body or they are doing finger-nose-finger movements. Essential tremor is usually not present at rest in contrast to the tremor of Parkinson's disease.

The patients usually give family history of tremor in their parents, siblings or close relatives. However, sporadic cases are seen very frequently. The exact mechanism of inheritance is not found. Some people use the term "Familial Tremor" for this and also the term of “Benign Essential Tremor" has been used. However, it is recommended not to use the word benign as essential tremor could be quite disabling. In a classic essential tremor the arms are affected in about 90% of the patients whereas head is affected only in about 30% of the patients, voice is affected in about 10% to 15% of the patients and legs are affected in about 25% of the patients. Patients with severe essential tremor may have trouble doing tandem gait which is tested by walking heel-to- toe or “walking as on a tight rope”. Otherwise their neurological examination is normal. Spiral drawing and handwriting specimen is consistent with tremor.

Essential tremor is more common than Parkinson's disease tremor. It affects about 5% to 6% of the patients over the age of 65. To detect essential tremor, patients are asked to make a pointer with their index finger and then touch the finger of the examiner and their own nose back and forth. They are also told to hold their arms with fingers apart in front of their body as well as in a wing beating position. Also the patients are told to hold a cup full of water and bring it to their lips and then away from their mouth few times and see if they spill any water or the glass shakes. They are told to write a sentence and also draw the Archimedes spiral. Their tongue should also be examined partially protruded with open mouth. Patients are also told to hold a prolonged note “EEEEEEEEEEEEE.” Involvement of legs is seen by heel-knee-shin testing. Before making diagnosis the other causes such as drugs, anxiety, hyperthyroidism, a task specific tremor like writing tremor, or tremor due to other focal neurological abnormalities should be excluded.

As mentioned earlier, most of the cases are sporadic, however some of the cases may show Mendelian patterns of inheritance. In the inherited cases, the autosomal dominant distribution has been seen with involvement of chromosome 3 and chromosome 2. However the first degree relatives of patients with essential tremor have more risk of developing the essential tremor. Essential tremor occurs in all populations across the world. Sometimes the ederly patients with essential tremor may be misdiagnosed as having Parkinson's disease because these patients may have mild cog wheel rigidity at their wrist or elbows. These patients may have a slight resting tremor which is actually a severe essential tremor which does not go away because of incomplete muscle relaxation.

DIAGNOSIS: The diagnosis of essential tremor is usually made by history and examination. The brain scans are usually normal in these patients. However, conditions like Parkinson’s disease, other focal neurological problems, history of use of medications like valproic acid, thyroxin and lithium should be excluded carefully. As mentioned before, essential tremor gradually worsens with age and eventually may interfere with activities of daily living, writing, employment, etc.

MANAGEMENT: For the management of essential tremor, any exacerbating factors should be addressed first. The two medications commonly used are beta-blockers and primidone. About 60% of the patients would have a 60% response from these medications.

1.) BETA BLOCKERS

Among the beta-blockers the most effective medication is propanolol. Some patients might take only 10 mg to 20 mg of propanolol tablet before performing social activities whereas other patients would prefer taking everyday medications. If propanolol is to be taken on daily basis, the dosage varies from 60 mg to 320 mg per day.

Side effects could be a slight drop in blood pressure, feeling tired, depression and impotence. Propanolol is contraindicated in patients with asthma, COPD or heart failure. Diabetes mellitus is also a relative contraindication as Propranolol can mask symptoms of hypoglycemia.

2.) PRIMIDONE

          Primidone is a medication used for epilepsy that was found to be helpful in the treatment of essential tremor. The initial dose is 62.5 mg once daily which could be increased slowly, however some patients have difficulty tolerating, and they might feel drowsy, dizzy with Primidone. If patients are compliant with this medication the side effects may go away in 2 to 3 weeks.

3.) OTHER THERAPIES

BOTOX injections may offer some improvement but may cause finger or wrist weakness in these patients.

Gabapentin was used in few studies and found to have mild to moderate effect. Other medications include benzodiazepines like clonazepam. Topiramate, an antiepileptic  medication also has mild to moderate effect in reducing essential tremor. The initial starting dose of topiramate is 25mg once a day which can be slowly increased overtime.

Surgical treatments are used for patients who have very advanced essential tremor and they fail pharmacological management. Two types of surgeries are done include thalamotomy and deep brain stimulation. Deep brain stimulation has shown greater improvement and fewer side effects as compared to thalamotomy. However these procedures are invasive and they do cause side effects like speech and swallowing difficulties, sensory disturbances and balance problems. There is also a risk of infection and haemorrhage. These surgeries are performed on the side of the brain contra lateral to the severe tremor.