Category: Otolaryngology

Throat cancer refers primarily to malignant tumours of the voice box and the lining of the muscular tube that lies behind it. The main risk factors are smoking and alcohol and these are synergistic when both factors are present. Throat cancer usually affects older males but it can also affect younger patients of any gender who are non-smokers and non-drinkers too. This article aims to inform the reader of the structure, disease process and management of this type of cancer and what to watch out for to avoid unnecessary delay in treatment.

Anatomy and physiology

The throat is a complex structure consisting of the muscular tube (pharynx) that connects the back of the nose and throat to the gullet (oesophagus) and voice box (larynx). It allows for the safe flow of food and fluids to the gullet and of air through the larynx into the lungs. The larynx consists of muscles, cartilage and nerves which are designed to safeguard the airway, protecting it from potential entry of food and drinks by “closing” itself off. This reflex is paramount in survival and is what allows us to thereafter generate immense force from our lungs to produce a cough to clear the airway. Failure to do so can result in choking and lead to chest infections such as pneumonia.

Other functions of the larynx include voicing and the capacity to strain and raise the abdominal pressure. There are three main parts of the larynx (Fig 1): the upper part is the supraglottis; the middle, the glottis – where the vocal folds/cords are located; and the lower part is the subglottis, where the voice box joins the windpipe (trachea). The lining of the throat is known as its mucosa. It is the toxic irritation of cigarettes and alcohol with their chemical compounds that alter the cells of the mucosa causing them to change their appearance and behaviour leading to an irreversible genetic alteration and to cancer. Genetic factors, exposure to certain chemicals and chronic exposure to acid, viral infections and other irritants have been postulated as causes in other patients.

Symptoms and signs

Patients with throat cancer present in several ways. Hoarseness in patients with no obvious precipitating cause exceeding a fortnight should be referred on for specialist investigation. Lesions on the true vocal folds affect their vibratory capacity and result in an abnormal rough voice. If the mass of the tumour or its extension reduce the mobility of either or both cords, the voice can sound breathy too. Swallowing difficulties and choking are also symptoms that can be present as signs of possible throat cancer.

Throat or ear pain on swallowing are also important complaints that warrant investigation. Blood in the saliva and increasing noise while breathing and shortness of breath can be later features of throat cancer and warrant rapid referral to an ENT surgeon. Patients with extension of their cancers may, rarely, present with disease that has spread to the lymph nodes in their neck which are often painless and hence should be seen urgently for further assessment.

History and examination

A full history is sought and risk factors ascertained. The state of the patient is appraised to assess the severity of the disease, especially in cases where the airway is either compromised physically, potentially leading to asphyxia, or in its inability to protect the lungs from aspiration of ingested solids and liquids. Thereafter, patients are examined with particular attention paid to their larynx, back of the tongue and side of their throats. This is achieved using a flexible fiberoptic endoscope known as a nasendoscope which is passed via the nostril, through the nose and above the voice box. Other methods of examining the larynx include using a laryngeal mirror and rigid endoscopes that are angled so they can visualise the throat through the mouth.

Investigations

Imaging of the neck and throat are achieved using sophisticated cross-sectional imaging modalities such as an MRI or CT scan. Further investigation includes examining the patient’s upper aerodigestive tract under a general anaesthetic with concomitant biopsies of the lesion/s in question with analysis by the pathologist. Thereafter, the confirmed cancer is staged and treatment recommended after discussion in a multi-disciplinary tumour board made up of specialist oncologists in surgery, radio and chemotherapy, pathology, radiology and specialist nurses, speech therapists and dietitians.

Treatment

Throat cancer may present at various stages, often divided into early or late. There are also pre-cancerous stages that if untreated may develop into cancer. Hence, treatment is tailored to the disease and patient along with risk factors such as persistent smoking, drinking etc. Early cancers can be treated with a single modality of treatment – that is, either by surgery alone or radiotherapy.

The decision to use a particular modality is made based on the site and accessibility of the  tumour, the ensuing risks to the voice and swallow and cost. Minimally invasive surgery utilising lasers (Figure 2A and 2B) has been well established as an effective method to treat laryngeal cancer. It is very accurate and can be repeated unlike radiotherapy that is often a one-off treatment and therefore rarely repeatable.

More advanced cancers require more aggressive treatment including the incorporation of chemotherapy where applicable to radiotherapy. Transoral robotic surgery has also been used to great success and in cases where patients may have already had radiotherapy and salvage surgery is advocated but carries higher risks of complications. Open surgery has become less common currently as “laryngeal preservation” is advocated to avoid what is generally a mutilating removal of the voice box with subsequent permanent changes to the patient. Total laryngectomy, however, in cases of advanced cancer is still a very oncologically sound and effective operation.

Voice rehabilitation

With the loss of the larynx comes the obvious loss of the capacity to speak. Along with this is the fact that the patient’s throat is no longer at the junction box between the airway (trachea) and food way (oesophagus). The patient therefore has a complete separation between the two tubes with the windpipe now attached to the skin of the neck below the removed voice box.

Various ways of voice rehabilitation have been developed including “oesophageal speech” where the patient swallows air and belches it out in a controlled manner causing vibration of the back of his tongue, mouth and lips while moving his tongue to speak. Other ways include the use of a speech valve – a purpose-built device that is inserted through the back wall of the windpipe into the oesophagus. This valve allows for the channelling of air from the lungs into the oesophagus and similarly out through the mouth causing vibrations that result in sound.

An electronic device that resembles a microphone known as an electrolarynx can be used and this transfers vibrations from the cheek to the device.

Finally, some patients rely on sign language and writing to communicate.

Conclusion

Laryngeal cancer is a cancer that can affect the young and old. It is seen in non-smokers and non-drinkers too. Symptoms that affect the voice box and throat that do not improve after a fortnight or so such as hoarseness, pain, swallowing problems, cough and shortness of breath should be referred on for specialist input quickly.

Asthma is a common medical condition affecting the lower respiratory tract. It affects all age groups, genders and is seen globally. It has several causes – namely genetic and environmental factors. However, in the absence of an obvious precipitant, it is often idiopathic (when the cause is unknown). Asthma is characterised by breathing difficulty, often at night and associated with wheezing, shortness of breath (hence its name from the Greek “to pant”), chest tightness and coughing. There are however other medical conditions which present in a similar vein which are characterised by noisy breathing when the patient is awake, strained/rapid breathing (and in severe cases) leading to cessation of breathing and death. Some of these conditions manifest very early in life and others in adulthood.

The aim of this article is to provide the reader with a few causes of breathing problems affecting children and adults that may occasionally be treated as asthma but affect the upper airway as opposed to the lungs.

Anatomy

The airway can be divided into two broad parts – the upper and lower. The upper part provides a common passage for food, fluid and air to pass through the oral cavity (such as from the nose for air) and into the back of the mouth and thereafter into the throat (pharynx). It is at this crossroads that our physiological control mechanisms separate what enters the lungs and what enters the gullet (oesophagus). The upper airway descends into our voice box (larynx) through the windpipe (trachea) and into the lungs which are found within the chest (thorax).

The narrowest portion of the child’s upper airway is just below the vocal folds (level of the cricoid cartilage) and above the start of the trachea while the adult upper airway is narrowest at the level of the vocal folds. The vocal folds are found within the voice box which is a cartilaginous structure comprising a shield-like structure and a complete cartilaginous ring. The level at which the vocal folds are is described as the glottis and following on, the area above the supragottis and below – the subglottis before descending into the trachea (Figures 1 and 2).

Noisy breathing

Not all noisy breathing is wheeze. Narrowing of the lower air passages with a characteristic high-pitched noise due to the vibration of the walls of the partially obstructed “air tubes” is effectively wheeze. A frequently confused sound which arises from laryngeal obstruction is called stridor. This sound is also high-pitched, often higher pitched than a wheeze and can vary depending on the location of the obstruction in the larynx and trachea i.e. being present when breathing in (inspiration), out (expiration) or both.

Another noise which is low-pitched and related to obstruction of air above the voice box, at the level of the back of the tongue or tonsils, is called stertor. These noises are present when the patient is awake, unlike snoring which is low-pitched noisy breathing when asleep.

Childhood conditions

Paediatric causes of breathing difficulties can be congenital and present very early in life. Severe cases of upper airway obstruction can be due to the incomplete canalisation of the tubular structures that eventually become the larynx and trachea. These conditions are rare and the milder forms may not present that early in life and become more evident as the child becomes more active or starts to make noises or speaks. Other conditions affecting the child but not present at birth are acquired and can be due to a variety of causes including infections, tumours, foreign body inhalation and neurological conditions.

Laryngeal webs

Mild laryngeal webs in children may cause noisy breathing which can be confused for a wheeze. As the child grows, parents may notice that their child has a hoarse voice and on exertion starts to “wheeze”. Mild laryngeal webs can be asymptomatic and go unnoticed for years, while more severe ones will manifest earlier. Surgery in symptomatic cases is the treatment of choice and is generally successful.

Laryngeal papillomatosis

Recurrent respiratory papillomatosis (RRP) is a viral infection of the upper airway – most commonly involving the voice box but occasionally the trachea and rarely (but potentially fatally) – the bronchioles (lung air passages). It is caused by the human papilloma virus (HPV) which causes skin warts and other tumours such as the cancers of the female cervix and palatine tonsil. The condition affects both adults and children although the disease profile is somewhat different with remission generally a feature in the childhood form. Despite this, many children with this condition can be misdiagnosed for having noisy breathing commonly ascribed to wheezing and if associated with a hacking cough – to croup (laryngotracheobronchitis).

Recalcitrant “wheeze” with hoarseness in children should therefore be a consideration for specialist ENT referral to assess the airway. Treatment of RRP can be fraught with multiple operations to reduce the bulk of viral growths and restore the airway while making every effort not to cause damage to the vocal folds that are very delicate and scarring of the airway.

Adult conditions

Unlike childhood causes of laryngeal obstruction, most adult onset upper airway conditions are acquired. Throat cancer is often seen in smokers and when tumours of the larynx narrow the air passage, the ensuing “noise” can be mistaken for a lower airway pathology. Operations to the thyroid, carotid arteries and upper spine can affect the nerves (causing various degrees of paralysis) that control the movement of the vocal folds and may be subtle – only becoming evident if a co-existing problem such as a throat infection worsens the airway resulting in noisy breathing/stridor. Here are some other interesting causes that may be mistaken for asthma:

Exercise-induced laryngeal obstruction

This condition is seen in young adults who are usually involved in high intensity sporting activities or exercise. The attacks of noisy breathing and breathlessness only come on when performing certain tasks but otherwise the subject is well when not under such duress. The confusion with asthma is common and diagnosis in subjects who already have asthma – difficult. Special investigations including a real-time examination of the patient’s larynx (continuous laryngoscopy examination, CLE) with a flexible nasendoscope while performing the said exercise is indicative but, in many instances, impractical.

Idiopathic subglottic stenosis

This condition is characterised by a deposition of scar tissue in the region of the subglottis below the true vocal folds and above the start of the trachea. It is almost exclusively seen in Caucasian women and is, as the name implies, of unknown cause. Treatment options include minimally invasive “closed” techniques which are performed through the nose using flexible endoscopes.

Conclusion

Upper airway narrowing in the context of the voice box and windpipe can be confused with asthma and leads to delays in the diagnosis and subsequent management of the root cause. It is worthwhile reconsidering whether patients who have been erroneously diagnosed with asthma really suffer from this condition. Recalcitrant cases or cases where two or more co-existing pathologies are present should be referred on to ENT surgeons for the necessary investigations and management promptly.

Dr Vyas Prasad
Senior Consultant Otolaryngologist Head and Neck Surgeon
MB BCh BAO BA (Dublin), MSc DIC (London), DLO (England), MRCS (Edin), FRCS (ORL-HNS)(Edin), FICS

THE BUSINESS TIMES WEEKEND, OCTOBER 19-20, 2019

Age-related hearing loss has wider ramifications

The Impact of hearing loss on health Issues such as cognition and dementia should be recognized and managed

Hearing loss affects an estimated 5 percent of the world’s population, and will affect twice that number (900 million) in 30 years. The majority of these will be adults and especially the elderly because of the declining population (in the developed world) with increasing longevity.

Besides the obvious disability that hearing loss is associated with are other equally compelling health issues that are important to recognise, prevent or manage. Cognitive impairment, dementia, depression and social isolation are several of the conditions that are associated with hearing loss in the elderly.

The aim of this article is to explain the fundamentals of the ear, mechanisms of hearing and the causes of hearing loss in the elderly briefly. Thereafter, a discussion on the impact of hearing loss on cognition and dementia is provided with ways of delaying these conditions.

Anatomy

The human ear consists of three parts, the external, middle ear and inner ear. The external and middle ear are air-filled, while the inner ear lies within the substance of the side bone of the skull – the temporal bone. The ear drum (tympanic membrane) separates the external ear from the middle. The Eustachian tube connects the front of the middle ear to the back of the nose.

Besides the three smallest bones of the human body – the malleus (hammer), incus (anvil) and stapes (stirrup) – the middle ear also contains important nerves that control facial movement, taste and salivation.

The inner ear has two main parts, the bony outer part and soft (membranous) inner part. Fluid bathes these two parts and important receptors for balance and hearing are activated according to the stimuli that reach them. Similarly, the nerves of balance and hearing pass back into the skull where they connect to the brainstem and brain.

How we hear

Sound is a form of energy created by cyclical compression and rarefactions (decompression) of any medium it travels through and is transmitted as waves across different media – air being the most obvious. As the waves pass by, they enter the ear canal cause the intact ear drum to vibrate and transmit the energy to three small bones in the middle ear – a purely mechanical process that aims to increase the efficiency of sound transmission.

This mechanical process transfers to the inner ear via the flat footplate of the stapes bone into the inner ear’s membranous part. Movement of this fluid excites specialized cells with hairs on their end changing their properties and causing the movement of charged electrical atoms, thereby generating electric current that flows in the nerve of hearing to the brain.

Assessing hearing loss

Hearing is assessed in several ways. History taking and examination can provide some clues as to how poor the patient’s hearing can be. Genetic causes, medication, trauma, noise exposure and infection can all affect hearing. Simple clinical assessment in the form of free field hearing tests provide quick and fairly useful information of the hearing capacity. Tuning forks are also used to assess hearing loss and whether or not it is related to conduction of sound through the external and middle ear (air conductive hearing) or to the nerve of hearing (sensorineural hearing).

Formal hearing assessment (eg. a pure tone audiogram) is done in a soundproof room and assesses the ability to hear pure tones (pitches / frequencies) at different sound levels)

Speech audiometry is performed in cases where hearing loss is severe to profound and when the subject is not benefiting enough from hearing aids. Other tests measure the compliance of sound energy transfer from external ear to the middle.

Finally, “electrical” testing of the inner ear and brain can be done to objectively assess hearing where the other “subjective” tests cannot provide an accurate gauge of the hearing loss.

Severity of hearing loss

Sound is measured using a special scale called the decibel (dB) scale. It is a mathematically derived scale and ranges from -10dB to 120dB in most settings. If the sound level at any frequency is 20dB or less (i.e. -10dB to 20dB), it is normal. The other categories are: mild hearing loss (20dB – 40dB), moderate (40dB – 70dB), severe (70dB – 90dB) and profound – any value beyond that. The World Health Organization defines a disabling hearing loss as any hearing above 40dB in adults and 30dB in children.

The ageing ear

As we age, it may seem unsurprising that our ears age too – the nerves of hearing and balance deteriorate due to “unavoidable” wear and tear.

The difficulty however is predicting who, why and when this process affects and whether or not it is purely a function of chronology. For example, not all individuals at 80 years are profoundly deaf, while some patients present at 50 and are already showing signs of severe hearing loss.

Ageing does need not be the single critical factor in what is often attributed as “age-related” hearing loss. Reduced blood flow to the brain, genetics, medication and other neurological conditions may have  an impact on hearing.

Mild cognitive impairment and dementia

By 2050, an estimated 131.5 million patients worldwide will have dementia. Recent studies have shown that cognition is significantly poorer in individuals with untreated hearing loss.

Hearing loss has been consistently shown to be associated with increased risk of developing dementia in the western world but the link with mild cognitive decline has yet to be established given the paucity of work in this regard.

The Singapore Longitudinal Aging Study is a multi-centre project involving several key opinion leaders who have varied backgrounds including ENT surgery and Gerontology / Geriatric Medicine (ref. Heywood and Ng). This study includes nearly 2,600 subjects and a follow up of eight years and has established that like the West, the Asian population is affected equally vis-a-vis cognitive impairment in hearing impaired subjects.

Treatment options

The results of the aforementioned study suggest several treatment options. Hearing aids have been the mainstay of treatment but in cases where they are clearly unhelpful given the severity of the loss, a speech audiometry may demonstrate that the patient, despite being “aided”, is still missing out on a lot of the sound stimuli.

Only 4.3 percent of 50- to 59-year-old and 22.1 percent of those above 80 years with hearing impairment wear hearing aids in the US.

Lack of awareness, stigma, persistently high cost and lack of reimbursement by insurance companies all contribute to the poor uptake of hearing rehabilitation.

In some cases where conventional hearing aids do not help, cochlear implantation is recommended. Cochlear implants have become more accessible and are being recommended to older patients with severe to profound hearing loss that need not affect all the hearing frequencies.

Given that hearing rehabilitation may slow down the progress of dementia and cognitive decline, recommendation for hearing rehabilitation should be made.

Conclusion

Hearing loss in the elderly has ramifications beyond just day to day sound perception and conversation. The increased cognitive load required to process sound in individuals with hearing loss may direct the innate cognitive resources away from centres for memory processing to centres for speech perception.

A focused approach to the elderly with this condition is essential in promoting health, social well-being and reducing cognitive decline and dementia.

Business Times
14-15 September 2019