Phantosmia and psychogenic non-epileptic seizures in a patient with burning mouth syndrome suffering from severe depression

Abstract

Burning mouth syndrome (BMS) is a rare but serious medical condition with important psychiatric comorbidity and specific psychological correlates. Psychopathology related with BMS represents a real challenge for clinical decision-making. In this case, depression is the leading psychiatric diagnosis associated with patient’s BMS somatic pain and is driven by anxiety and a dissociative functioning. Facing a complex psychosomatic symptomatology, we offer new clinical perspectives for the screening of psychological traits of BMS. Moreover, we highlight the need to foster interdisciplinarity to improve differential diagnosis and defining an optimal care path. This case report stimulates a reflection on management challenges for the consultation–liaison psychiatry and shows the importance of a person-centred approach when communicating the diagnosis.

Background

Burning mouth syndrome (BMS, also referred to as burning mouth disease or glossodynia) is a rare but serious medical condition with important psychiatric comorbidity and with a high negative impact on functionality and quality of life.¹ Persistent and severe localised perioral burning pain is experienced by patients and accompanied by oral dysesthesia, decreased or impaired taste and xerostomia. There is no actual consensus on its classification or definition, even if there is increasing evidence that BMS could be a neuropathic disorder.^{2 3} The International Association for Study of Pain has described BMS as a chronic condition characterised by a burning sensation of the oral mucosa for which no cause can be found.⁴ In the International Classification of Orofacial Pain, it has been classified as idiopathic orofacial pain with or without somatosensory changes.⁵ The general prevalence of BMS is 0.01%–0.02%, confounded by age and gender. The mean age is approximately 60 years old, and is slightly higher in women than in men.⁶ Establishing a BMS diagnosis requires relevant care investments by the patient and his clinicians: as a medical unexplained physical symptom (MUPS) it challenges underestimation or leads to unnecessary investigations.⁷ Differential diagnosis typically involves different medical specialties such as pain and oral medicine, gastroenterology, neurology, internal medicine and psychiatry. Looking into BMS seems to produce a prismatic effect, it presents itself indeed as a complex and multifaceted syndrome for every clinical discipline.

Psychiatric and psychological studies and case reports indicate in fact the co-occurrence of anxiety, depression and personality disorders in association with the invalidating pain condition.^{8 9} Among personality traits, research has particularly investigated neuroticism with components of introversion and hostility.^{10 11} A recent study has shown that neuroticism correlates with a more serious condition for BMS patients with and without a psychiatric history of depression.¹² Alexithymia, a psychological trait elevated in individuals with chronic pain,¹³ should be routinely screened in those patients.^{14 15} Catastrophising, one of the most influential psychological factors negatively associated with pain perception and prognosis, should be assessed as well.¹⁶ All these psychological factors are relevantly associated with somatisation and somatoform diseases.^{17 18} Unsurprisingly, somatisation is as well associated with BMS, in particular, functional somatic syndromes have been observed as salient comorbidity.^{2 19} If BMS has often been attributed to a psychosomatic condition, the evidence contradicts the central sensitisation theory linking this pain condition with other pain syndromes such as fibromyalgia.²⁰ However, BMS enters in differential psychiatric diagnosis with somatic symptom disorder for the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) or somatoform disorder for the International Classification of Diseases, 10th Edition (ICD-10).²¹

Psychiatric comorbidity is important for BMS and a pathogenetic model hypothesises that orofacial pain could be seen as a somatic feature of depression, triggered by the demoralisation induced by anxiety.²² Despite advances in research, BMS aetiopathogenesis remains unclear at present, psychogenic factors, and peripheral and central neuropathies appear to be jointly implicated.²³ No more certainty exists at the therapeutic level. Evidence on the most effective treatment is scarce, especially for short-term relief (up to 3 months), but a consensus exists on the need for a long-term multidisciplinary intervention combining topical and psychiatric pharmacological treatment with psychotherapy.^{24 25}

In this case report of BMS, we relate many of the previously described psychopathological and psychometric aspects with the addition of specific MUPS symptoms such as hyperosmia, phantosmia and an episode of psychogenic non-epileptic seizure (PNES), which, to our knowledge, have not been previously described. Hyperosmia is defined as an amplification of the olfactory sensibility, and it has different causes (genetic, hormonal, neurological, infectious, environmental). Phantosmia, or olfactory hallucination, is the perception of smells that are not present in the environment, and it has different possible aetiologies, typically neurological (epilepsy in the temporal lobe) or psychiatric.²⁶ PNES are operationally defined as episodes of altered movement, sensation or experience similar to epilepsy, but caused by a psychological process and not associated with abnormal electrical discharges in the brain.²⁷ In the DSM-5, PNES is considered as a subtype of functional or conversion/somatisation disorders. Such specific severe psychopathological correlates of BMS motivated us to review the literature looking for structural phylogenetic organisation of the symptomatology as to provide the best treatment options. This clinical presentation offers indeed new insight into the discussion of psychiatric comorbidity of BMS and adds new perspectives for an integrated consultation–liaison (C–L) psychiatry model and a person-centred approach to this disease.

Case presentation

A 69-year-old man has been referred by the general practitioner to the outpatient’s internists of the hospital, to better explore a complex presentation of symptoms: perioral burning pain, hyperosmia, painful abdominal paraesthesias, weight loss. A diagnosis of BMS was posed, with differential diagnoses including a post-COVID-19 syndrome, a dysimmunopathy, a corticosteroid deficiency, a paraneoplastic syndrome, an intestinal parasitosis and drug toxicity. Somatic investigations followed by a psychiatric and psychological evaluation for investigating somatisations were organised for establishing the differential diagnosis.

Somatic investigations, such as laboratory tests including screening for autoimmune diseases, gastrointestinal endoscopy, ears, nose and throat and allergological evaluations, abdominal CT scan, cerebral magnetic resonance, did not reveal pathological conditions.

The psychiatric evaluation, requested by the internist to evaluate a possible somatisation, assessed depressive symptoms that met the ICD-10 criteria for a severe depressive episode without psychotic symptoms: low mood, apathy and anhedonia, reduction of energy, loss of self-confidence and self-esteem, death thoughts, reduced concentration and attention, sleeping disturbance, diminished appetite, difficulty in dealing with normal daily activities.

The patient had not experienced previous depressive episodes in his life. The psychological assessment showed as well high anxiety and elements of alexithymic functioning characteristics of somatisation. Traits of introversion and obsessive thought were observed during the clinical evaluation, with particular focus on somatic concerns, assessed through significant catastrophising scores, especially for helplessness and rumination (see table 1 for detailed psychometric and pain evaluations). The reported stressful context given by the COVID-19 pandemic, in particular coping with personal loss, was concomitant with the onset of symptomatology. The patient comes from Italy within the borders of Switzerland, where different members of his family live. Unfortunately, during the first pandemic lockdown, his mother died. He could not visit her due to public health measures between the two countries. Most of the contacts with his family were interrupted. His work activity in a factory stopped as well. He describes a withdrawn daily life and a strong dependence on his wife for all normal activities. During the first clinical assessment, sertraline was prescribed to treat depressive symptoms, together with zolpidem, already prescribed by the general practitioner. The patient did not tolerate the antidepressant (general malaise), which was interrupted after some days.

Table 1.

Timetable of psychometric and pain evaluations

	Time	MADRS	HADS anxiety	HADS depression	TAS-20	PCS	VAS Pain
Outpatient evaluation	First evaluation	43	14	10	71	37	10
Inpatient evaluation	Admission	/	16	7	/	/	8
	Discharge	32	8	3	/	/	7
Outpatient follow-up	1 month	/	10	5	/	/	/
	2 months	/	6	4	/	/	/
	3 months	1	4	1	50	25	4

MADRS,⁴¹ cut-off scores: 0–6—normal/symptom absent, 7–19—mild depression, 20–34—moderate depression, >34—severe depression; HADS,⁴² anxiety and depression cut-off scores: 8/21; TAS-20⁴³: cut-off score: 61/10; PCS⁴⁴: cut-off score: 30/52.

HADS, Hospital Anxiety and Depression Scale; MADRS, Montgomery-Asberg Depression Rating Scale; PCS, Pain Catastrophizing Scale; TAS, Toronto Alexithima Scale; VAS Pain, Visual Analog Scale for Pain.

A few days after the interruption of sertraline, the patient was hospitalised for 1 week due to an episode of psychogenic non-epileptic seizure, triggered by an olfactory hallucination (phantosmia). At home, lying on the sofa, the patient perceived a disturbing smell (similar to a female perfume, without real stimuli, as testified by the patient’s wife). Then he presented a similar tonic–clonic seizure without loss of consciousness, corresponding to the criteria of dissociative (conversion) disorder—dissociative convulsion for the ICD-10. The symptoms regressed after the administration of oral lorazepam 1 mg by the rescuers, whose had been alerted by the patient’s wife. The week of hospitalisation was a turning point in the clinical history of the patient, as he was monitored by different specialists (internist, neurologist, psychiatrist, psychologist) in regular comparison with each other, and as he felt reassured by the hospital context. He expressed feelings of trust and said he felt ‘treated as a person’. A family conference informing about the psychiatric comorbidities and psychological assessment was organised. The patient showed good motivation to try an antidepressant again, therefore he started, as inpatient, oral escitalopram (up to 10 mg), together with zolpidem and lorazepam. Brief integrated psychodynamic psychotherapy intervention was initiated within the hospitalisation and planned after discharge with regular weekly consultations.

Differential diagnosis

It is not easy to establish if BMS, hyperosmia, phantosmia and PNES were related or independent comorbidity conditions of depression.

The clinical presentation of depression was ‘masked’, not recognised by the patient and not even by the internists, and likely showed through the suffering body.²⁸ Depressive symptomatology required a specific assessment by the psychiatrist and psychological evaluation. Somatisation was effectively associated to the depressive state; however, it did not meet the criteria for establishing a diagnosis of somatoform disease for the ICD-10. In particular, neither the duration of symptomatology nor the persistent request of medical exams were present. Moreover, the follow-up suggests that BMS and hyperosmia were probably comorbidities that persisted, even if in significant reduced form, after the clinical resolution of depression. PNES and phantosmia could instead represent more likely clinical manifestations strictly connected with depression. For these reasons, we consider depression as ‘the leading diagnosis’ of the multidisciplinary therapeutic process in this clinical case.

PNES has high rates of psychiatric comorbidity overall, notably including post-traumatic stress disorder, depression, and personality and anxiety disorders.²⁹ According to this study, patients with PNES often present somatic symptoms rather than psychological distress. For this reason, clinicians need to be aware that depression might present as focused on somatic symptoms.³⁰ Olfactory hallucinations have been described in somatoform dissociation, possibly associated with PNES.³¹ However, for establishing an accurate differential diagnosis, it should be noted that olfactory dysfunctions might represent clinical manifestations of temporal lobe epilepsy. In a population-based study olfactory hallucinations have been reported as associated with anxiety and stressful life events.³² In a study with veterans, increased distress has been found to be linked to specific smells experienced during traumatic episodes.³³ Meanwhile, the association between olfaction dysfunction and depression is known in the psychiatric literature, in particular depressed patients tend to show a lower olfactory identification capacity,³⁴ in contrast to our patient, who showed an upper olfactory identification capacity. Further future investigations are needed to better clarify these aspects as well as to link the different clinical symptoms observed in this clinical case to a common ground in terms of brain networks changes.

Outcome and follow-up

During the weeks of posthospitalisation follow-up the patient presented a progressive and consistent clinical improvement of anxiety and depression, a significant reduction of the BMS symptoms, and a complete remission of episodes of phantosmia. During the follow-up the patient did not present any other PNES. To exclude temporal lobe epilepsy, he also had a further neurological evaluation and performed an electroencephalogram with temporal electrode montage that resulted normal.

Psychotherapy intervention focused on alexithymia through the writing of personal thoughts and memories initiated spontaneously by the patient during the hospitalisation. Scores of alexithymia and pain catastrophising significantly improved (table 1). After 3 months of regular psychotherapy treatment, monthly follow-up consultations jointly with psychiatric monitoring were sustained.

Discussion

The available guidelines and systematic reviews for the treatment of BMS do not give any evidence-based indications,^{24 35} we think therefore that the observations on the diagnostic and treatment process described in this clinical case could be useful in fostering a best practice and informing future clinical trials. In particular, our observations will focus on the relevance of information and communication in the treatment of BMS.

This clinical case highlights the need for a liaison model in consultation psychiatry, defined as a ‘broader role (for the psychiatrist) (…) integrated into the work of their general hospital colleagues’.³⁶ In the reported case, hospitalisation in a medicine department with a C–L psychiatry intervention represented indeed a ‘turning point’ in the clinical course of the patient, with a length of stay reduced in comparison to classic psychiatric inpatient treatment for depression.³⁷ It has allowed to build and consolidate physician–patient trust, initiate a stable psychotropic treatment and start psychotherapeutic intervention. Without the possibility of assuring multidisciplinary continuity, within the care path of this patient (from outpatient first evaluations to inpatient acute stabilisation and outpatient treatment and follow-up) would probably have been postponed and less effective. Furthermore, the patient, faced during his acute phase with a profound anguish and threatened by loss of sense of meaning and self-esteem, has expressively talked about his gratitude for being ‘treated as a person’. Information and communication played a central role. They are well recognised as a central point in MUPS; specific high communication skills and emotional competence are indeed required by practitioners.³⁸ First, the hospital somatic assessment played a role of reassurance, probably diminishing the patient’s health anxiety. Then, the possibility to understand the psychological factor associated with the pain syndrome, as well as to share those insights with his relatives, was of great value to the patient. The disclosure of emotional components of pain in BMS and co-occurrent diagnosis of PNES was not only well received by the patient and his relatives, but also seen as a confirmation of their shared suspects about what was the psychological trigger of the disease. The integrated approach described in this case could actually be seen as consistent with the person-centred approach in medicine, focused on individual needs besides the tendency to reduce the people to their disease or to institutional issues.³⁹ The person-centred approach has been highlighted by recent conceptualisations in the biopsychosocial model in C–L psychiatry and could be seen as a promising theoretical foundation for the organisational development of the discipline.⁴⁰

Patient’s perspective.

Our patient expressively talked about his gratitude for being ‘treated as a person’. Information and communication indeed played a central role during his care path. The experience of recovery from illness has changed his communication modalities as well. First, the patient started writing personal thoughts on his condition during the hospitalisation and discussing them with the psychotherapist. Afterwards, he started to tell more to his relatives and friends about his health condition. He talked about being mentally ill, namely, he spoke about ‘nerves problems’, a common local expression referring to depression. Openness to others contributed to relieve the feeling of isolation and shame in social contexts. The following quotes are transcriptions of his writings notes.

During the hospitalisation

Admitted by ambulance for a nervous breakdown treated with a pill. My wife was frightened, she displaced me. In the emergency room, I made all the visits to calm down. Then transferred to a room. Everyone very nice, compliments to the nurses.

Now I'm being treated by the (name of the psychologist and the psychiatrist), hopefully, everything will be ok.

I took a blood sample and went for a walk in the corridor, thinking to be with my wife by the hand. (Name of the psychologist) passed for a visit. Then he came back with other doctors for consultation and discussion. Today, I realised that many doctors do not care much about people’s morale and say things point blank. Most are very human and sincere.

During the follow-up

Yesterday, I came home after 8 days of hospitalisation. I was hospitalised because I had nerve problems.

Bad day, little desire. Burning in the mouth, nose, palate and ears all day and a lot of agitation. Went for a walk but with little desire […]. It is hard not to think on such a day. We went for a walk with my wife to get rid of the crisis. When I know that someone’s coming to visit me, I get a bellyache.

Since the last time we saw each other, everything went well without any problems, both for the holidays and for everything. We ate a lot during the holidays. Bicycling on the road and rollers and long walks. Friends and brothers-in-law have not abandoned me, especially my brother-in-law. My wife never abandoned me, she pampered me. My sisters call me every day to see how I am.

Learning points.

• In burning mouth syndrome (BMS), the presence of dissociative or somatic symptoms of depression should be assessed.

• Consultation–liaison psychiatric evaluation and psychotherapeutic follow-up are needed in BMS cases.

• The diagnostic work-up should be shared with the patient, in case of complex somatic symptom’s presentation.

Ethics statements

Patient consent for publication

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