Gabapentin as a potential treatment for cough syncope

Cough medicines for children- time for a reality check

Cough medicines have been in use for over a century to treat the common and troublesome, but often helpful, symptoms of cough in children. They contain various combinations of "anti-tussive" drugs including opioids, antihistamines, herbal preparations, mucolytics, decongestants and expectorants. Whilst theoretically attractive for symptom relief when children are suffering, as time has passed these popular over the counter medicines have been shown to lack efficacy, delay more serious underlying diagnoses, and can cause complications and sometimes death. This has resulted in clinician concerns, a citizen petition to the American Food and Drug Association in 2007, some self-regulation from manufacturers and escalating restrictions on their use from regulatory agencies across the world over the last twenty years. This article will review the protective role of cough, juxtapose the conflicting treatment goals of suppressing a dry cough and promoting expectoration for a wet cough, consider the evidence basis for prescribing cough medicines in comparison to other more specific treatments such as for asthma [beta agonists] or infection [antibiotics], regulatory interventions, and conclude with the view that over counter cough medicines should not be used in children, especially young children.

Can clinical characteristics differentiate patients with unexplained chronic cough from patients with asthma and COPD?

Background: Chronic cough is reported in up to 20% of the adult population and often persists despite medical treatment with currently available therapies. Many clinical conditions, including asthma and chronic obstructive pulmonary disease (COPD), must be excluded before making a Unexplained chronic cough diagnosis. Methods: The primary objective was to use a large hospital dataset to compare clinical features of patients with a primary diagnosis of UCC with those with asthma or COPD without a primary diagnosis of UCC to help clinicians differentiate between these conditions more readily. Data were collected for all hospitalization and outpatient medical encounters for each patient between November 2013 and December 2018. Information included demographics, encounter dates, medications prescribed at every encounter for chronic cough, lung function testing, and hematologic parameters. Asthma and COPD were combined into one group to ensure there was no overlap with UCC and due to limitations of International Classification of Diseases coding to confirm an asthma(A)/COPD diagnosis. Results: Female gender represented 70% of encounters for UCC versus 61.8% for asthma/COPD (p < 0.0001); the mean age was 56.9 years for UCC versus 50.1 years for A/COPD (p < 0.0001). The number of patients on cough medications and the cough medication frequency were significantly higher in the UCC versus A/COPD group (p < 0.0001). UCC versus A/COPD patients had a total of eight versus three cough-related encounters over the study duration (i.e., 5 years) (<0.0001). The average interval between successive encounters was less for UCC (114 days) versus the A/COPD (288 days) group. Gender-adjusted Forced expiratory volume in the first second of exhalation/Forced vital capacity (FEV₁/FVC) ratios, residual volume%, and Diffusion capacity for carbon monoxide (DLCO%) were significantly higher in UCC versus A/COPD, whereas the response to bronchodilators of FEV₁, FVC and residual volumes were significantly greater in A/COPD patients. Conclusions: Clinical characteristics differentiating UCC from A/COPD could accelerate recognition of UCC diagnosis especially in the subspecialty setting where patients with these disorders are referred.

Cough syncope and hyperventilation-induced convulsion in Chiari 1.5 malformation

Chiari malformation type I (CM1) is defined as cerebellar tonsillar herniation below the level of the foramen magnum. Syncope, especially cough syncope, is a rare but important symptom of CM1 patients. Here, we report a CM1 patient, in combination with brainstem herniation (CM1.5), presenting with repetitive syncope who was successfully treated by decompressive surgery. A 43-year-old right-handed male, with 5-year history of repeated episodes of loss of consciousness in association with cough, was investigated. Neurological examination revealed slight muscle weakness, clumsiness, and sensory disturbance in the left upper limb. There was no sign of orthostatic hypotension or orthostatic intolerance. Cranial and spinal magnetic resonance imaging revealed a herniation of the cerebellar tonsils and a syringomyelia. Forced hyperventilation during electroencephalogram (EEG) induced brief generalized symmetric clonic convulsions with preserved consciousness, but no overt EEG seizure patterns or slow activities were found. Based on the diagnosis of CM1.5 with recurrent episodes of loss of consciousness, he underwent foramen magnum decompression. He has no recurrence of the episode after the surgery on 1 year follow-up. Decompressive surgery was an effective procedure for cough syncope and other symptoms of the current patient with CM1.5. Dissociation of cerebrospinal fluid pressure between the cranial and spinal compartments which leads further herniation of the cerebellar tonsils and subsequent compression on the cerebellum and the brainstem is considered to be the major mechanism of his cough syncope. Analysis of EEG can be useful not only to diagnose epileptic seizures but also to elucidate mechanisms of syncope and concurrent involuntary movements.

Treatment of Chronic Refractory Cough in Adults: Focus on Neuromodulators and Other Therapeutic Modalities

Objective: To evaluate the literature and educate health care professionals about the different management options for chronic refractory cough (CRC). Data Sources: Searches were performed through MEDLINE (1966 to July 2020) using OVID and EBSCOhost and EMBASE (1947 to July 2020) using OVID. Search terms included chronic cough, neurogenic cough, neuromodulators, chronic cough management, and chronic cough treatment. References of all relevant articles were further used to obtain additional articles. Study Selection and Data Extraction: This review includes articles in the English language and human trial literature. Twenty-three trials explored the use of oral neuromodulators in the management of CRC. Data Synthesis: CRC is a poorly understood disease that may have a complex neuropathic etiology. Oral neuromodulators, such as amitriptyline, baclofen, gabapentin, and pregabalin, continue to be the most commonly used agents for the management of CRC. Alternative pharmacological therapies such as botulinum toxin, anesthetic agents (benzonatate, lidocaine), and narcotic agents have efficacy data, and further research into effective doses and routes of administration is warranted. Alternative nonpharmacologic therapies more commonly used included speech pathology treatment. Conclusion: Several medication and alternative treatment interventions may be effective in managing CRC. Current studies used wide dosing and titration strategies, making it challenging to standardize therapy. No consistent method of assessing cough reflex was used between studies, as well as a lack of consistent randomization and small sample sizes. Additional research is needed to standardize treatment durations, optimum doses, and place in therapy of the available interventions in the management of CRC.

The Wide-Ranging Spectrum of Cough-Induced Complications and Patient Harm

Cough is one of the most common complaints encountered in every setting; however, complications associated with coughing have received relatively little attention. An exhaustive systematic review of the English literature revealed an exceedingly large and varied spectrum of cough-induced complications affecting many systems, including upper airways, chest wall and thorax, abdominal wall, heart and aorta, central nervous system, eye, gastrointestinal tract, urogenital system, and emotional and psychological harm. Prospective studies and prevalence data are conspicuously missing. Reported cough-induced pathology ranges from rare (the majority) to common and from trivial (eg, lightheadedness, subconjunctival hemorrhage) to severe and life-threatening (eg, cervical artery dissection, rupture of a normal spleen). Other seemingly benign entities may mask a serious underlying pathology (eg, cough headache, cough syncope). A substantial proportion of patients experience anxiety and insomnia, and their quality of life is affected. Thus, the wide spectrum of cough-induced pathology need to be recognized and considered in patients complaining of cough. Suppression of cough must not be neglected in patients at risk, and areas of uncertainty need to be clarified by future prospective studies.

Cough syncope induced by post nasal drip successfully managed by Gabapentin

Syncope is a common complaint in both neurology clinic and emergency department. It is defined as transient loss of consciousness with loss of postural tone, which is usually self-limited and followed by a spontaneous recovery. Our report describes a case of cough syncope resulting from chronic intractable cough caused by post nasal drip. Although his experience was debilitating, we were able to control his symptoms significantly using a small dose of Gabapentin. This dose is much lower when compared with the already established licensed indicated higher doses used for the treatment of neuropathic pain and epilepsy. Cough syncope is a demanding condition that results in comprehensive costly investigations. In addition, cough syncope could be misinterpreted as epilepsy by the treating team. Pulmonologists should be aware of the use of Gabapentin as the management of cough refractory to standard antitussive therapy. Further studies are needed to assess the effectiveness of low doses of Gabapentin in the management of chronic cough.

Towards understanding and managing chronic cough

Chronic cough is a common and troublesome condition affecting approximately 12% of the general population. It is associated with poor quality of life with psychological, social and physical consequences. Patients typically complain of a dry irritating cough, driven by a strong urge to cough associated with a sensation or irritation located in the throat. Treatment of potential 'causes', ie asthma, gastro-oesophageal reflux disease and rhino-sinusitis, may produce a complete or partial response, but the response of some patients to opiates and alpha-2-delta ligand antagonists (gabapentin and pregabalin) supports the concept that this is primarily a neurological disorder, characterised by hyper-responsiveness of the nerves. Novel and highly effective neuronal treatments are in development and offer hope of better symptom control with fewer side effects within a few years. This review focuses on understanding the mechanism of chronic cough, current management approaches and research that may lead to novel therapies.