Little has been published about the progression of neuropsychiatric features in SC. Extensive semi-structured interviews elicited accounts of the longer-term course of SC in patients referred to psychiatry from a UK regional paediatric neurology service. From symptom onset SC could be distressing for the family as well as the patient, with psychiatric symptoms an early feature. Sometimes, early physical signs of chorea were poorly recalled, but a wide range of physical symptoms was identified, some were disabling, and most resolved but persistent signs of chorea were elicited in 5/12. Possible predisposition to neuropsychiatric symptoms of SC is suggested by pre-existing developmental and neurological conditions and pre-existing emotional and behavioural vulnerabilities in this study. In most cases, signs of behavioural, psychiatric, and cognitive problems emerged over a significant period, related to the onset of physical symptoms. Some, seemingly in keeping with temperament, were present prior to SC onset but others were noticed early in the development of SC, sometimes before the importance of physical symptoms had been recognised.
The KSADSPL provided a framework for detailed exploration of the experience of SC and psychiatric diagnoses found are in keeping with previous research [4]. Psychiatric disorders were often time-limited but varying prolonged neuropsychiatric sequelae and relapses impacted on function. Rates of current psychiatric morbidity and co-morbidity appear high in comparison to population norms (eg 7/12 children reached criteria for a current ADHD diagnosis at interview and as the sample comprises around half of those diagnosed with SC, this represents around 30% of all children diagnosed, compared with an average 5% global prevalence for ADHD, [19]. This prevalence of ADHD in SC is in keeping with previous research [20], one American study using KSADSPL [21] found a similar rate of ADHD present even before onset of chorea. Variation in reports of ADHD symptoms over time may reflect difficulty in using KSADSPL retrospectively to distinguish ADHD symptoms from motor restlessness secondary to active chorea [14]. Affective and anxiety disorders are prominent as reported in SC [22], whilst separation anxiety has been particularly associated with PANDAS [23]. It is striking that hallucinations sufficient for a DSM diagnosis of psychosis were recorded in two cases.
Early stages of SC presentations included both high levels of physical impairment and psychiatric symptoms, which can be frightening for children and families, yet diagnosis was sometimes delayed and not all subjects were recognised as requiring paediatric review at first presentation. The specific experience of chorea is not often recalled as a prominent feature of the acute illness, which could lead to misdiagnosis both at initial assessment and in re-presentations with predominantly psychiatric symptoms [14]. Difficulties may arise if a clinician does not recognise the rare presentation of chorea and delayed diagnosis could contribute to high rates of psychiatric symptoms occurring before the diagnosis of SC [14, 24, 25].
A predisposition to SC is suggested by findings of developmental delays and pre-existing neurological conditions as well as descriptions of pre-existing emotional and behavioural vulnerability. Family histories of RF are in keeping with known heritability [26]. Family histories of psychiatric disorder are of interest, but numbers too small to suggest links to a child’s vulnerability to SC as nearly half of UK adults report that they had had at least one of eight forms of common mental disorder in their lifetime [27]. Maternal depression after onset of SC may reflect disease-related stress, associated with adverse psychological adjustment in caregivers and children [28].
The rate of persistent difficulties appears higher than found in a sample from a non-psychiatric setting [29], perhaps a result of different methodology in a retrospective review but children with SC complicated by psychiatric symptoms may have a more difficult course with varying neuropsychiatric sequelae of SC and chorea relapse. Patients’ experiences of physical and psychiatric aspects of SC in relapses and in some cases persistently support the case for on-going collaborative management from Neurology and Psychiatry [24]. The range of drug prescriptions further supports a joint approach. For example, there may be increased risk of motor side effects of psychiatric medication in SC [14, 24, 25]. Recurring and persisting psychiatric symptoms after streptococcal infection and in the absence of ongoing chorea indicate parallels between SC and PANDAS. Snider and Swedo [30] and Mabrouk and Eapen ([31] both suggested that PANDAS has a more sudden onset with psychiatric symptoms of OCD and tics, whereas patients in this study with a mixture of psychiatric symptoms, generally described more gradual onset. Some had current signs of chorea without reporting a subjective experience of chorea on direct questioning and chorea was often not specifically described as a symptom of past episodes, even in children who were quite severely affected. Thus, if insufficient attention was given to the history and there was no specific examination, the diagnosis of SC could be missed, and patients might be diagnosed incorrectly as having PANDAS [31]. Relapsing and remitting symptoms characterise the complex course of SC with psychiatric co-morbidities, associated educational difficulties and behavioural problems challenging services. “Working diagnoses” may be helpful, with watchful waiting before completing diagnoses with lifelong implications, such as ADHD or ASD.
Care after diagnosis fitted contemporary guidance that management of SC requires a clear explanation of the likely course of the disorder and advice regarding prevention of rheumatic heart disease with long-term penicillin, with occupational therapy, physiotherapy, support with schooling and medication if required to decrease the burden of abnormal movements [24]. These patients presented before the current interest in immuno-modulatory therapies such as corticosteroids, intravenous immunoglobulins (IVIGs) and plasma exchange which may shorten the course of the illness and prevent complications [32].
The children described represent around half of patients diagnosed with SC in the West of Scotland tertiary service during a 3-year period of increased SC presentations suggesting a regional annual incidence of SC of around 2–3 per 100 thousand children, 10 times greater than that found by Crealey et al [12]. Some milder cases may not have been identified and not every child with a diagnosis of SC will have reached specialist services. It is possible that not all patients with psychiatric symptoms were referred to Neuropsychiatry. Cases may be atypical as this cluster of SC presentation is unusual and its cause unknown. With a 75% response rate it is unfortunate that there is little information about non-responders.
Limitations
The interview provided only limited information on the condition of SC per se. Very detailed exploration being limited to the most severe episode means that some pre-morbid conditions may not have been fully delineated and limits the available detail about psychiatric symptoms occurring before the diagnosis of SC. Psychiatric diagnoses depend upon KSADSPL, which does not include educational or cognitive reports that contribute to diagnoses in clinical practice and is not specifically validated for use with co-morbid neurological disorders [17]. The validity of retrospective identification of tics and motor over-activity in the presence of a movement disorder is not established [14] which may be a particular difficulty in relation to reports of tics prior to SC diagnosis. Clinicians, parents and patients may experience difficulty in discriminating between tics and choreiform movements as in a recent case study [33]. Rates of psychiatric disorder in a highly specialist clinic may be poor indicators of prevalence of psychiatric disorder in SC.
Further studies are required to place these findings in the wider context of the incidence and course of SC in Western Europe [20, 21]. Increasing recognition of SC as a rare neuropsychiatric disorder could improve the quality of diagnostic practice and subsequent interventions. This might support a better understanding of the relationship between SC and related concepts such as PANDAS [30]. Future research could explore the possibility of a predisposition to neuropsychiatric symptoms in SC and a possible excess of psychiatric disorder in families [20, 21], which may imply genetic vulnerability to neuro-psychiatric symptoms.