Evidence-based management of a patient with anosmia Geyer, M. & Nilssen, E
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Evidence-based management of a patient with anosmia Geyer, M. & Nilssen, E. Department of Otorhinolaryngology, Head and Neck Surgery, Queen Alexandra Hospital, Cosham, Portsmouth, Hampshire PO6 3LY, UK A 52-year-old female comes to the out patient clinic with a 4-month history of anosmia and reduced taste. Anosmia is defined as loss or absence of the sense of smell. It is a common condition and affects approxi- mately 1% of the population under age 60 years. 1 Olfac- tory function also decreases with aging. 2–4
Abnormalities of olfaction include: (i) anosmia (inability to detect odours), (ii) hyposmia (diminished olfactory sensitivity) and (iii) dysosmia (distorted identification of smell), which includes (a) parosmia (altered perception of smell) and (b) phantosmia (smelling non-existent odours). 5 Loss
of smell often manifests as a loss of taste. In addition, cranial nerves V, IX and X sense noxious stimuli. 6 Disorders of smell may be broadly classified into three groups: (i) conductive (transport) loss: conditions that interfere with access of the odorant to the olfactory neu- roepithelium, (ii) sensory loss: injury to receptor region or (iii) neural loss: damage of central olfactory pathways. 7 The three most common causes of olfactory disorders are: (i) sinonasal disease ( 25%), (ii) postviral anosmia ( 20%) and (iii) head trauma (15%). What should you cover in the history A thorough history will provide important clues as to the aetiology and is a cornerstone of making a correct diag- nosis.
8 1 Onset. A viral upper respiratory tract infection precedes the onset of anosmia in around 20% of patients. Postviral anosmia is more common in those over 40 years and is usually reported within 6 months of the infection. 9 Head trauma is complicated by anosmia in 15% of cases, and is usually of immediate onset, but often only recognised once the patient recovers from their head injury. How- ever, of all head trauma cases, only 0.5–5% present with anosmia. Shearing force on olfactory filaments, olfactory bulb contusion and frontal lobe injury are proposed potential causative mechanisms. 10 The degree of olfactory loss may be associated with severity and site of cranial trauma. An occipital blow is commonly implicated. 2 Duration. Spontaneous return of function is known to occur if anosmia or hyposmia has been present for <2 years after a viral infection or head trauma. If present for longer than 2 years the condition is likely remain permanently. 11 3 Nature of the disorder of smell. In postviral cases, hy- posmia or dysosmia are more likely to occur than anos- mia. This is typically either a constant foul smell or a distortion of normal smell. 12,13
4 Related sinonasal disease. Twenty to 30% of patients have nasal and sinus disease, most commonly polyp dis- ease, 14
15 or allergic rhinitis. 16 Sino-
nasal disease is the most treatable aetiology of anosmia. Although nasal obstruction of the olfactory cleft, second- ary to nasal mucosal swelling, polyps, bony deformities and rarely tumours can result in anosmia, olfactory sensi- tivity does not correlate with nasal patency alone. 5 Episodic improvement and previous olfactory dysfunction. Patients with episodic loss may be more likely to recover function, and may benefit from topical nasal treatment. 6 Associated otorhinolaryngological symptoms. Complaints such as epistaxis, nasal obstruction, an enlarging neck mass or focal neurological deficits are important warning signs and symptoms and should alert the physician to a possible neoplastic cause, such as an aesthesioblastoma or meningioma, though often these tumours remain silent and often present late. 7 Taste loss. Two-thirds of patients complain of taste loss but only few actually have taste changes identified by test- ing. Thus, most patients have normal taste thresholds. 17,18 However, 67% have objective changes of their sense of smell and complain of a loss of flavour detection, which is mainly an olfactory function. 8 Medical conditions. Systemic disease such as endocrine disturbances (e.g. hypothyroidism, diabetes mellitus) and neurological conditions (e.g. temporal lobe epilepsy and schizophrenia) 19 may present with disorders of olfaction. 9 Smoke and chemical exposure. Exposure to cigarette smoke and other toxic chemicals can cause damage to the olfactory epithelium. Examples of agents associated with olfactory dysfunction include organic compounds (e.g. acetone, benzene, ethyl acetate), industrial agents (e.g. paint solvent), dusts (e.g. cement), metals (e.g. lead, zinc, mercury) and inorganic compounds (e.g. ammonia, car- bon monoxide). Spontaneous recovery can occur if the insult is discontinued. 20 A 1 2 M INUTE C ONSULTATION Ó 2008 The Authors 466
Journal compilation Ó 2008 Blackwell Publishing Ltd • Clinical Otolaryngology 33, 466–469 10 Medications. Anosmia is a complication of many med- ications and therefore a drug history is important. Com- mon medications to ask about include antidepressants (e.g. Amitriptyline), antihypertensives (e.g. Enalapril, Nifedipine, Propranolol), anti-inflammatory agents (e.g. Penicillamine), antimigraine agents (e.g. Sumatriptan), antineoplastics (e.g. Cisplatin), antipsychotics (Trifluoper- azine), and antithyroid agents (Propylthiouracil). 21 What should you cover on examination Meticulous physical examination is essential and should include a full ENT examination as well as a careful neu- rological evaluation as appropriate. 1 Nasal examination. Rhinoscopy is the cornerstone of assessment. Anterior rhinoscopy in the non-decongested nose should be supplemented with post-decongestant flexi- ble endoscopy of the nasal cavity, postnasal space, pharynx and larynx. Inflammation, mucopurulent discharge, polyps and masses are indicative of an underlying pathology. 2 Otoscopy. Serous otitis media suggests the presence of a nasopharyngeal mass or inflammation. 3 Neck. Palpate for pathologically enlarged lymph nodes. 4 Neurological examination. Carefully examine all cranial nerves where appropriate and look for signs of raised intracranial pressure such as papilloedema. 5 Sensory evaluation. Assessment of olfactory function corroborates the
patient’s complaint, evaluates the
efficacy of treatment and determines the degree of permanent impairment. 22 Although many testing kits are available, it is our experience that outside major centres they are still not used widely in the clinical setting, and considerable variation is present in the reliability of olfactory tests. 23 • Determining qualitative sensations by smell testing (odour identification tests). There are a variety of commercially available olfactory tests. The University of Pennsylvania Smell Identification Test (UPSIT) is an example of such a test. 24 The UPSIT involves 40 microencapsulated odours in a scratch-and-sniff format, with four forced choice response alternatives accompanying each odour. The scores are compared against sex- and age-related norms. Anosmic patients score at or near chance (10 ⁄ 40 correct). Malingering occasionally occurs, and should be considered in patients scoring 5 or less. The UPSIT test-retest reliability is high (r ¼ 0.92). 24,25
• Determining the detection threshold. By using successive dilutions of phenylethyl alcohol (PEA) detection thresholds can be established 26 (r ¼ 0.88). 24 The ‘Sniffin’ Sticks’ system uses n-butanol pen-like odour dispensing devices that contain different concentrations of odours.
27 Threshold testing by
evoked response measurement is used in the research setting.
28 What management should you offer 1 Laboratory investigations. Based on history and physical examination, tests to exclude renal, hepatic and various endocrine disorders may be obtained. They are not other- wise recommended as routine tests. Allergy testing as appropriate should also be considered. 2 Biopsy. Olfactory epithelium biopsy is generally not undertaken except in the research setting. 29 3 Radiological investigations. CT and MRI imaging may be ordered if indicated by the history and examination. 30 • CT scan: Patients with signs and symptoms of sino- nasal disease should be treated in the usual way. If they fail to respond to appropriate treatment then they would undergo imaging as part of their subse- quent management. Patients with sinonasal symptoms but without any obvious pathology found on examina- tion should also undergo a scan of the paranasal sinuses as part of the evaluation of their symptom complex. This identifies a group of patients who may benefit from either further medical and ⁄ or surgical intervention if an abnormality is confirmed on imag- ing. 31
form plate and anterior skull base and may provide evidence of local bone erosion or destruction, but will not readily pick up intracranial soft tissue disease. • MRI scan: Patients without evidence of sinonasal dis- ease on history or examination should have an MRI scan of the brain to exclude a sensorineural cause for their anosmia. This will exclude uncommon tumours of the anterior cranial fossa and brain, such as menin- giomas, aesthesioblatomas, and craniopharyngiomas. 32 1 Conductive (transport) olfactory loss Treatment of sinonasal conditions should be evidence based, as provided by the recently updated EPOS docu- ment, 33
scope of this article. 34 Briefly, topical nasal steroids have been shown to have some benefit in certain trials. 22 Other modalities include a short course of oral steroids, antibi- otics, hyposensitisation and surgery where appropriate. 35 Furthermore, a short course of oral steroids may help to diagnose reversible conductive loss. 2 Sensorineural olfactory loss • Few of the sensorineural olfactory defects have specific treatments. Traumatic and postviral anosmia should be treated expectantly, accepting that no specific treatment is proven to lead to a resolution of symptoms. 36 Patient reassurance and education is A 12 minute consultation 467
Ó 2008 The Authors Journal compilation Ó 2008 Blackwell Publishing Ltd • Clinical Otolaryngology 33, 466–469 vital. Steroids may be used in an attempt to reduce inflammation in cases of viral illness, sarcoidosis and multiple sclerosis. • There is scanty evidence confirming the efficacy of treatment of idiopathic sensorineural olfactory loss. Zinc sulphate is best known, but appears unsuccess- ful. 37
38 • Rare tumours of the anterior cranial fossa are treated by neurosurgical, radiotherapy and chemotherapy intervention as indicated. 3 Smoking cessation. Elimination of this and other air- borne toxins may help to restore olfactory function. 4 Patient reassurance and education. Once the relevant investigations have proven negative the patient may be reassured that they do not have a deleterious underlying pathology. Unfortunately, a cure is often difficult to obtain. The psychological and potential health impacts of disorders of olfaction are well recognised, especially in the elderly. Anosmia may adversely affect appetite, leading to lack of interest in eating and malnutrition, complicated by weight loss and a general adverse impact on health. 39,40
Hazards resulting from this disorder also need to be highlighted. It is important to warn the patient that an olfactory disorder will render them unable to detect cer- tain hazards, and lifestyle adjustments may be necessary. For example, smoke and natural gas detectors are essen- tial to minimise risk in the home environment. 41 Patients
should also be warned to pay attention to the sell-by-date on food to avoid eating items which are spoiled. Search stategy Current texts, the Cochrane library and other evidence- based databases were searched in the preparation of this paper. The current peer-reviewed literature was also searched using Medline under the MeSH heading ‘anos- mia’ and using subheadings for epidemiology, therapy, drug therapy and surgery. The search was limited to the English language, human studies and to clinical trials, randomised controlled trials and meta-analyses. The search was performed on 1 July 2008. Conflict of interest None to declare. References 1 Deems D.A., Doty R.L., Settle R.G. et al. (1991) Smell and taste disorders, a study of 750 patients from the University of Penn- sylvania Smell and Taste Center. Arch. Otolaryngol. Head Neck Surg. 5, 519–528 2 Murphy C., Schubert C.R., Cruickshanks K.J. et al. (2002) Preva- lence of olfactory impairment in older adults. JAMA 18, 2307– 2312.
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