A case of tics presenting as chronic intractable cough successfully treated with tetrabenazine.

Sir,

Gilles de la Tourette syndrome is a motor disorder. The prevalence of Tourette syndrome is stated to be about 4.9/10,000 males and 3.1/10,000 females.[1]

Prevalence studies indicate a 10-fold higher rate of Tourette syndrome among children compared with adults.[2] Tic disorders presenting during adulthood have infrequently been described in the medical literature. Most reports depict adult onset secondary tic disorders caused by trauma, encephalitis, and other acquired conditions. Only rare reports describe idiopathic adult onset tic disorders, and most of these cases represent recurrent childhood tic disorders. Adult onset tic disorders represent an under-recognised condition that is more common than generally appreciated or reported.[3]

We report a case of a man who presented with tics in the form of intractable cough. A 62-year-old unemployed man presented each time to various outpatient departments with the complaint of cough. He was first seen in April 1990 with a presenting complaint of dry cough with no history of wheezing. There was no history of associated hypertension, diabetes, ischemic heart disease, tobacco smoking or alcohol consumption. With minor variations such as production of minimal white sputum and slight wheezing with nocturnal worsening, he was managed with the same medication as the first visit with marginal improvement of symptoms. These included cough suppressant syrups, theophylline, and salbutamol inhaler. This went on till August 2003 when his diagnosis was altered to cough variant bronchial asthma owing to his exposure to woodwork in the past, with an additional differential diagnosis of pneumoconiosis.

He was first referred to the pulmonologist in December 2010 when a diagnosis of moderate persistent asthma was made, and further evaluation was considered in the form of spirometry and chest X-ray. By June 2011, when the cough persisted despite all interventions, he was advised to undergo dynamic computed tomography-scan of the chest and diagnostic bronchoscopy to rule out proximal bronchiectasis, both of which were normal. He was given homeopathic tablets, and later Ayurvedic treatment to relieve his symptoms, but found no relief despite continuing with the same for about 6 months, during which period his cough and jerks worsened. His cough was noted to be dry and grunting type while the jerks comprised of shoulder movements and “shaking” in the legs.

By April 2006, a diagnosis of “psychogenic cough” was recorded, and he was referred to psychiatry. He was put on a combination of haloperidol 1.5 mg in the night, trihexiphenidyl 2 mg in the morning, and fluoxetine 20 mg in the night. This combination was persisted with over several years, with only minor variations in doses of individual medication and the addition of prednisolone on one occasion, as well as a continuation of bronchodilators and cough syrups.

A further ENT referral during May 2013 showed no abnormality in his throat or vocal cord in a video laryngoscopic examination. During psychiatric consultation, he was commenced on tetrabenazine 12.5 mg in the night in the same month, in addition to the haloperidol and fluoxetine. During his review in June 2013, he reported an improvement in his symptoms, and by July 2013 his tics had stopped completely. By December 2013 the haloperidol and fluoxetine were reduced in dose, and he was advised to continue tetrabenazine at a dose of 12.5 mg once a day. He continues to maintain his improvement with no recurrence of cough till date.

Cough that lasts for >8 weeks is considered to be chronic. Usually, a syndromal approach is advised and 90% of chronic cough is found to be due to three major causes: Upper Airway Cough Syndrome, Gastro-oesophageal Reflux Disease or cough-variant asthma, all of which were ruled out in his case. It is further recommended that in adult patients with chronic cough, the diagnoses of habit cough or psychogenic cough can only be made after an extensive evaluation has been performed that includes ruling out tic disorders and uncommon causes and cough improves with specific therapy such as behaviour modification or psychiatric therapy. Indeed, a diagnosis of unexplained cough, rather than a habit cough or psychogenic cough is further recommended after ruling out the above causes.[4]

Since tetrabenazine has both presynaptic mono-amine depleting effects and postsynaptic blocking action, it is said to have an advantage over drugs that are dopamine blockers, with the additional benefit of less side-effects compared to antipsychotics. The dramatic improvement in cough with a small dose of 12.5 mg suggests that tetrabenazine has a role to play in the management of tics – both typical and atypical.