Gender Differences in Tremor

By Jean P. Hubble, MD

The diagnosis is usually quite obvious – rhythmic shaking of the hands. Despite the fact that essential tremor (ET) is common and easily recognized, there are many aspects about the clinical presentation which are poorly understood.

Virtually all individuals with ET have tremor of the hands. The next most frequently affected body areas are the head and voice. Head and voice tremor occurs in about 30 percent of ET patients in most reports. It is possible that age, duration of the tremor disorder, or gender might be predictive of the clinical expression of ET, including affected body region. To test this notion, we conducted a study at the University of Kansas Medical Center Tremor Clinic in 1992-1995. The results of this work were reported in the journal Movement Disorders, 1996, Volume 12, pages 969-972.

Clinical information obtained from 450 ET patients was analyzed. The average age was 67 years while the average duration of tremor was 25 years. There were 232 men and 209 women included in this analysis. Nearly all of the study subjects including men and women had tremor in the hands. However, only 30 percent of the men had tremor affecting the head and voice while 60 percent of the women had tremor of the head and voice. In addition, hand tremor was more severe in men and head and voice tremor was more severe in women. Thus, women were more often affected by tremor of the head and voice and had more severe head and voice tremor compared to men. There is no ready explanation of this finding.

It is possible that the sex chromosome (X<Y) influences the expression of tremor in men compared to women. Alternately, the sex hormones (estrogen, progesterone, and testosterone) may influence the location and severity of tremor in some way.

Another explanation for these findings is that women with tremor may have another neurological symptom called “dystonia.” Dystonia refers to involuntary, sustained muscle contractions, which can cause unusual postures including head turning. It is possible that some of the head tremor in subjects participating in the study was due to dystonia of the neck (torticollis). In contrast to gender, age and duration of tremor did not distinguish those individuals who had tremor affecting the head and voice from those who had hand tremor only.

Unfortunately, there are few effective remedies for head and voice tremor. Sometimes, the conventional tremor medications will help suppress head tremor to some degree. These medicines include propranolol, primidone, and clonazepam. Botulinum toxin injections into the neck muscles may help suppress head tremor. However, botulinum toxin injections can result in transient muscle weakness so that the patient who undergoes injections may have difficulties with head droop or difficulties with swallowing for several days or a few weeks. Botulinum toxin injections may help voice tremor when it is associated with dystonia of the vocal cords (muscle contractions of the vocal cords). Deep brain stimulation of the VIM nucleus of the thalamus has been shown to improve head and voice tremor in some patients.

Part of the limitation in our ability to better treat tremor is due to the fact that the causative brain mechanisms for tremor are not precisely understood. It is possible that a better understanding of the brain chemistry in ET will lead to better treatments.

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This article is taken from “Essential Tremor: What the Experts Say” third edition published in 2014 by the IETF. At the time of its publication, Dr. Jean Hubble was senior medical director, U.S. WorldMeds, New York, NY.

Record Clinical Trial Enrollment Made Possible by IETF and Their Members

Patient recruitment is usually the biggest challenge in conducting clinical trials. Thanks to the International Essential Tremor Foundation and their members, Cala Health recently enrolled the largest therapeutic essential tremor study in record time.

By Kate Rosenbluth,
Founder/CEO of Cala Health, Inc.

About five years ago, my co-founders and I spun Cala Health out from Stanford University to develop a wearable therapy for essential tremor. We spent several months observing and interviewing patients, neurologists and neurosurgeons, and were captivated by the unmet need to give people back their hand control without undergoing brain surgery. The International Essential Tremor Foundation and its members gave generous time to helping us understand the condition and how we could help. We formed a company and began product development of a peripheral stimulation device worn on the wrist to interrupt the tremulous signal driving the tremor in the brain.

Photo of Cala CEO Kate Rosenbluth

Our careful research and development process brought us to the final stage, clinical trials. Clinical trials produce the most reliable data available for health care decision making. They follow strict scientific standards to protect patients and produce dependable study results. Oftentimes, the single greatest challenge in conducting a successful clinical trial is recruiting participants. Typically, most participants are recruited by physicians serving as Principal Investigators for the study, or by engaging advertising agencies to inform potential participants that a clinical trial is available. This can take months, if not years, and require significant investment in advertising.

Fortunately, Cala Health has partnered with the International Essential Tremor Foundation, who announced this research opportunity to their members nationwide. We immediately received interest from qualified participants who have been struggling with essential tremor for years and connected them with the leading neurologists in movement disorders who were participating in our trial. We have been so pleased with the response. Most recently, this generated and enrolled hundreds of patients into our PROSPECT study in record time. During the study, patients wore the therapy on their wrist like a smart watch and patterned electrical stimulation was delivered to the nerves through the skin twice per day over a three-month period. This fast enrollment enables a key milestone to share the results later this year and make this FDA-cleared therapy commercially available. 

People who take part in clinical trials are vital to the process of improving medical care. IETF is an essential partner to Cala Health informing the ET community of the clinical research opportunities to advance medical knowledge and patient care.

About Cala Health, Inc.

Cala Health is a bioelectronic medicine company transforming the standard of care for chronic disease. The company’s wearable neuromodulation therapies merge innovations in neuroscience and technology to deliver individualized peripheral nerve stimulation. The first indication for Cala Health’s wearable therapy is essential tremor, a disease experienced by more than seven million people and characterized by severe hand tremors. Visit www.CalaTrio.com to learn more.  New therapies are under development in neurology, cardiology and psychiatry. The company is headquartered in the San Francisco Bay Area and backed by leading investors in both healthcare and technology.

Research Brings Hope for a Brighter Tomorrow, and World Without Essential Tremor

We sometimes take for granted the vast history of medical research and its impact on human ailments and diseases. Most people have heard of polio and tuberculosis, which today are easily preventable with a vaccine. Organ transplants extend life for many and the pacemaker regulates the heart’s rhythm for people with irregular heartbeats. Physicians can remove cataracts and cancerous tumors, and use artificial insemination to help couples conceive.  And surgical options for essential tremor (ET), including focused ultrasound and deep brain stimulation, have enhanced the quality of life for thousands. None of these would be possible without medical research.

The International Essential Tremor Foundation (IETF) knows through continued medical research, there will one day be improved treatments and possibly a cure for essential tremor. So each year, we continue to fund research projects to address the nosology, etiology, pathogenesis and other topics relevant to essential tremor. Through promoting and awarding research grants, we also know we can stimulate inquiry into essential tremor (ET) by leading scientists.

IETF Research Appeal Graphic 2019

July is a time when we focus on essential tremor research and work to raise money for research grants. Since 2001, the IETF has dedicated more than $800,000 toward essential tremor research and we are not done yet.

This year, we presented a $25,000 research grant to Dr. Adrian Handforth with The Veterans Affairs Greater Los Angeles Healthcare System. His research project is titled, Evaluation of an a6ßy2 GABA Receptor-Specific Drug as Potential Therapy. It will explore the potential of developing a drug that mimics how low doses of alcohol can suppress the effects of tremor, but with more selectivity of molecular targets to try to avoid adverse effects found with other medications used for management of essential tremor.

Please consider supporting our “Shine a Light on Essential Tremor Research Campaign” this month. Watch for a special letter in your mailbox outlining how you can help. Or go online and make a donation.

Research provides hope for all of us, and means a better and brighter future for the next generation. Perhaps our scholarship recipient, Deirdre, summarized it best when she said:

New and ongoing research for ET gives hope to us young people. Even though our conditions may worsen over time, there are also so many ways that modern medicine can help us live our lives normally and we all need to work toward that goal together.”