Propranolol, clonidine, urapidil and trazodone infusion in essential tremor: a double-blind crossover trial

Fragile X premutation and associated health conditions: A review

Fragile X syndrome (FXS) is the most common single gene disorder, which causes autism and intellectual disability. The fragile X mental retardation 1 (FMR1) gene is silenced when cytosine-guanine-guanine (CGG) triplet repeats exceed 200, which is the full mutation that causes FXS. Carriers of FXS have a CGG repeat between 55 and 200, which is defined as a premutation and transcription of the gene is overactive with high levels of the FMR1 mRNA. Most carriers of the premutation have normal levels of fragile X mental retardation protein (FMRP) and a normal intelligence, but in the upper range of the premutation (120-200) the FMRP level may be lower than normal. The clinical problems associated with the premutation are caused by the RNA toxicity associated with increased FMR1 mRNA levels, although for some mildly lowered FMRP can cause problems associated with FXS. The RNA toxicity causes various health problems in the carriers including but not limited to fragile X-associated tremor/ataxia syndrome, fragile X-associated primary ovarian insufficiency, and fragile X-associated neuropsychiatric disorders. Since some individuals with neuropsychiatric problems do not meet the severity for a diagnosis of a "disorder" then the condition can be labeled as fragile X premutation associated condition (FXPAC). Physicians must be able to recognize these health problems in the carriers and provide appropriate management.

Current and Future Neuropharmacological Options for the Treatment of Essential Tremor

BACKGROUND

Essential Tremor (ET) is likely the most frequent movement disorder. In this review, we have summarized the current pharmacological options for the treatment of this disorder and discussed several future options derived from drugs tested in experimental models of ET or from neuropathological data.

METHODS

A literature search was performed on the pharmacology of essential tremors using PubMed Database from 1966 to July 31, 2019.

RESULTS

To date, the beta-blocker propranolol and the antiepileptic drug primidone are the drugs that have shown higher efficacy in the treatment of ET. Other drugs tested in ET patients have shown different degrees of efficacy or have not been useful.

CONCLUSION

Injections of botulinum toxin A could be useful in the treatment of some patients with ET refractory to pharmacotherapy. According to recent neurochemical data, drugs acting on the extrasynaptic GABAA receptors, the glutamatergic system or LINGO-1 could be interesting therapeutic options in the future.

Treatment of fragile X-associated tremor ataxia syndrome (FXTAS) and related neurological problems

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive neurological disorder that affects older adult carriers, predominantly males, of premutation alleles (55 to 200 CGG repeats) of the fragile X (FMR1) gene. Principal features of FXTAS are intention tremor, ataxia, parkinsonism, cognitive decline, and peripheral neuropathy; ancillary features include, autonomic dysfunction, and psychiatric symptoms of anxiety, depression, and disinhibition. Although controlled trials have not been carried out in individuals with FXTAS, there is a significant amount of anecdotal information regarding various treatment modalities. Moreover, there exists a great deal of evidence regarding the efficacy of various medications for treatment of other disorders (eg, Alzheimer disease) that have substantial phenotypic overlap with FXTAS. The current review summarizes what is currently known regarding the symptomatic treatment, or potential for treatment, of FXTAS.

Benefits and risks of pharmacological and surgical treatments for essential tremor: disease mechanisms and current management

Essential tremor (ET) is a neurological disease (and possibly a family of diseases) whose most recognisable feature is an action tremor of the hands and occasionally of the voice and head. Current data support the view that CNS gamma-amino-butyric acid (GABA)-ergic mechanisms may underlie ET and that the tremor may be further modulated by peripheral (muscle) adrenoreceptors. Potential pharmacotherapeutic options, targeted to influence the activity of the neurotransmitter GABA within the CNS and the peripheral adrenergic receptors, are part of the current armamentarium to treat ET. As such, primidone and propranolol remain the mainstays of the therapy for ET. Intramuscular injections of botulinum toxin A may play a role in the treatment of voice and head tremor. Surgical options, which are reserved for patients with severe, medically-refractory tremor, provide adequate tremor control in the majority of patients. As with other progressive neurological disorders of late life, the ability to use neuroprotective medications to intervene in the developing disease to either slow or halt the progression of the pathological process, would involve an understanding of underlying disease mechanisms. The understanding of these mechanisms in ET is limited and further study of these mechanisms is critical for the development of such therapies.

Essential Tremor

BACKGROUND

Essential tremor (ET) is the most common adult tremor disorder and is characterized by postural and kinetic tremor. Symptoms are typically progressive and potentially disabling, often forcing patients to change jobs or seek early retirement. Proper treatment is contingent on a correct diagnosis, and other possible causes of tremor must be excluded.

REVIEW SUMMARY

Although primidone and propranolol have been regarded as the mainstays of pharmacologic therapy for ET, additional agents may be useful in reducing tremor. Surgical procedures are available that effectively ameliorate tremor that is refractory to medical management. This article reviews the epidemiology, pathophysiology, and treatment options for ET.

CONCLUSIONS

Despite a range of treatment options currently available, further research is necessary to manage this syndrome most effectively. Double-blind, controlled trials are needed to determine whether primidone, propranolol, or a combination of these medications is superior in the initial management of ET. Other pharmacologic agents have shown potential to reduce tremor and should be investigated further. Additional studies are also needed to determine the best treatment of head and voice tremor with pharmacologic and surgical interventions. With proper treatment, tremor is sufficiently reduced in the majority of patients.

Benefits and risks of pharmacological treatments for essential tremor

Essential tremor can cause significant functional disability in some patients. The arms are the most common body part affected and cause the most functional disability. The treatment of essential tremor includes medications, surgical options and other forms of therapy. Presently there is no cure for essential tremor nor are there any medications that can slow the progression of tremor. Treatment for essential tremor is recommended if the tremor causes functional disability. If the tremor is disabling only during periods of stress and anxiety, propranolol and benzodiazepines can be used during those periods when the tremor causes functional disability. The currently available medications can improve tremor in approximately 50% of the patients. If the tremor is disabling, treatment should be initiated with either primidone or propranolol. If either primidone or propranolol do not provide adequate control of the tremor, then the medications can be used in combination. If patients experience adverse effects with propranolol, occasionally other beta-adrenoceptor antagonists (such as atenolol or metoprolol) can be used. If primidone and propranolol do not provide adequate control of tremor, occasionally the use of benzodiazepines (such as clonazepam) can provide benefit. Other medications that may be helpful include gabapentin or topiramate. If a patient has disabling head or voice tremor, botulinum toxin injections into the muscles may provide relief from the tremor. Botulinum toxin in the hand muscles for hand tremor can result in bothersome hand weakness and is not widely used. There are other medications that have been tried in essential tremor and have questionable efficacy. These drugs include carbonic anhydrase inhibitors (e.g. methazolamide), phenobarbital, calcium channel antagonists (e.g. nimodipine), isoniazid, clonidine, clozapine and mirtazapine. If the patient still has disabling tremor after medication trials, surgical options are usually considered. Surgical options include thalamotomy and deep brain stimulation of the thalamus. These surgical options provide adequate tremor control in approximately 90% of the patients. Surgical morbidity and mortality for these procedures is low. Deep brain stimulation and thalamotomy have been shown to have comparable efficacy but fewer complications have been reported with deep brain stimulation. In patients undergoing bilateral procedures deep brain stimulation of the thalamus is the procedure of choice to avoid adverse effects seen with bilateral ablative procedures. The use of medication and/or surgery can provide adequate tremor control in the majority of the patients.

A multicenter randomized crossover multiple-dose comparison study of arotinolol and propranolol in essential tremor

BACKGROUND

A new medication is needed to treat essential tremor. Preliminary evidence suggests that arotinolol may be effective in the treatment of this disorder.

OBJECTIVE

To study the effect of arotinolol and propranolol in a crossover, multiple dose comparative trial of patients with essential tremor.

PATIENTS AND METHODS

One hundred and seventy-five outpatients, with essential tremor were included in the study; 161 patients completed the study. Patients were identically evaluated at eight consecutive visits. The study consisted of two treatments, which were arranged according to a crossover design that evaluated the dose of each (arotinolol 10 mg per day and propranolol 40 mg per day, arotinolol 20 mg per day and propranolol 80 mg per day, arotinolol 30 mg per day and propranolol 160 mg per day). Each course of treatment lasted 6 weeks. Major outcome evaluations consisted of a self-reported disability scale, and motor performance score obtained before drug intake and 14 days after each treatment. The treatment effects were evaluated by analysis of variance using the Hills-Armitage test.

RESULTS

Arotinolol was found to be as effective as propranolol at reducing tremor. Drug effects as evaluated using motor-task performance scores revealed that arotinolol had a more significant effect than propranolol.

CONCLUSIONS

Arotinolol may be more useful than propranolol for the treatment of essential tremor.

Clinical and electromyographic assessment of essential tremor treatment

It is a matter of debate whether beta-blockers or primidone have a better influence on essential tremor. It is also controversial whether essential tremor with synchronous electromyographic activity is influenced by the administration beta-blockers, while tremor with alternating electromyographic activity is influenced by primidone. The aim of this study was to reevaluate the effects of beta-blockers and primidone on essential tremor. We also aimed to evaluate the differential effects of beta-blockers and primidone on tremor with synchronous or alternating electromyographic activity and on tremor in different limb positions. One hundred patients (57 female, 43 male) with essential tremor were included in this study. According to the electromyographic pattern recorded from the antagonistic muscles, the patients were subdivided into group with synchronous (SYN) and group with alternating (ALT) activity. After the initial clinical and electromyographic examinations the patients were randomly assigned first to treatment with propranolol (180 mg daily), or to treatment with primidone (500 mg daily) for 30 days. After a washout period of 20 days the patients were assigned to the other treatment. Our results revealed that the effects of propranolol and primidone on essential tremor and on SYN or ALT tremor were similar. Differences between both drugs existed as regards to better primidone influence on the kinetic and intention tremors and to tremor localized outside the limbs. In conclusion it is better to treat patients with kinetic and intention essential tremor and tremor localized outside the limbs with primidone.

Phenomenology and treatment of tremor disorders

Tremor is classified according to anatomic distribution among body parts, and by frequency and amplitude during rest, postural maintenance, movement, intention, and the performance of specific tasks. Key historical features include age at onset, progression over time, family history, exacerbating and remitting factors and behaviors, response to alcohol and medications, and additional neurological signs and symptoms. Accurate diagnosis is a critical factor in predicting the natural history and response to treatment.