Prognosis and time course
A Pubmed search on a CFS prognosis was done with the search terms ("chronic fatigue syndrome" OR "Myalgic Encephalomyelitis") AND prognosis AND (young OR pediatric OR paediatric OR teenager OR adolescent) revealing 1,350 results. Titles and abstracts were screened and the relevant articles full text were read of which nine stated the course or prognosis of CFS (4–12). References in relevant articles were also screened revealing two additional articles (13, 14).
CFS can begin suddenly or gradually with a spectrum of severity of loss in physical and cognitive functioning, with mildly affected patients being able to attend school full time or part time with a limitation in sport and after school activities and school absences(7). Severely affected patient may be homebound or wheelchair bound with inability to participate in home tutoring sessions (7). Affected adolescents can make a full recovery with time, patience, explanation of factors contributing to illness, and managing setbacks (4).
A thirteen year follow up of 35 children and adolescents found that the average age of disease onset was 12 and that 37.1% considered themselves resolved of illness; 42.9% considered themselves well but not resolved; 11.4% considered themselves chronically ill; and 8.6% considered themselves more ill than before (14). Eight participants (22.9%) missed more than two years of school (14). The impact of the illness was most evident in terms of education (6).
In another study of 25 adolescents with CFS, 68% were unable to attend school with a mean time of 1 year out of school (8). The mean duration of illness was 37.5 months (8).
An observational study of 784 young people attending a paediatric outpatient service found that the mean duration of illness was 5 years with 38% and 68% of patients reporting recovery by 5 and 10 years respectively, with depression, anxiety and severity of illness being non predictive of recovery (9).
In contrast, a systematic review of 26 studies found an older age, more chronic illness, having a comorbid psychiatric disorder and holding a belief that the illness is due to physical causes are factors for poor prognosis(13).
A longitudinal study of 13, 978 children found that 75% of adolescents with chronic disability fatigue recovered after two to three years (10).
Pathophysiology and triggers
CFS is proposed to be caused by an immune system dysfunction, hypothalamic pituitary, or adrenal gland dysfunction, or central and autonomic nervous system abnormalities. Predisposing factors include being female in post pubertal adolescents with prevalence being 3 – 4 times higher than in boys, and also a family history of CFS (7). Viral infection, such as Epstein-Barr virus or human herpesvirus 6 infection are possible precipitating factors (15)(16). In some patients no physical or emotional trauma, over exertion or no precipitating factors have been identified (7). Cytokine expressions have been implicated in CFS; the “cytokine storm” exhibited by some COVID-19 patients has been hypothesized to lead to post infectious fatigue (17). Perpetuating factors include a late diagnosis, overexertion resulting in “crashes,” stress, inadequate sleep (7).
A pubmed search for case reports on CFS with the following search terms (chronic fatigue syndrome) NOT adult AND (evidence) NOT (covid-19) NOT (protocol)) AND (case study) revealed two articles (18)(19). The first showed elevation of choline concentration in the brain of three patients with CFS indicating abnormal cerebral blood flow. The second was a case report showing parvovirus infection should be excluded in patients with CFS.
Evaluation
A careful history taking including precipitating factors, sleep disturbances and psychosocial stressors is needed. OSA screening can be done e.g. using STOP-BANG questionnaire. Red flag symptoms to rule out include chest pain, dyspnoea, lymphadenopathy, weight loss, inflammatory signs or joint pain, and focal neurological deficits. These may point towards cardiac, pulmonary disease, malignancy, autoimmune disease, and central nervous system malignancy/ abscess/ multiple sclerosis (20).
Examination may include signs of low blood pressure or orthostatic hypotension, tachycardia, a positive rhomberg sign, low oral temperature or slightly elevated body temperature <37.7 degrees (15).
Testing is done to confirm or exclude other causes of fatigue or syndromes (see section on differentials below). These may include a full blood count, glucose, calcium, electrolytes, renal and liver function tests, and thyroid function tests. Depending on the symptoms/ signs, other tests such as evaluation for adrenal insufficiency, creatinine kinase for muscle pain or weakness, or sleep study is performed if sleep apnoea is suspected. Neuroimaging is not routinely performed.
In the primary care setting, patients are periodically followed up and laboratory investigations done as required. Comorbidities such as anxiety and depression identified. Although a diagnosis requires at least six months of illness, this time period should include follow up appointments, complete investigations and allow time for improvement for children with illnesses with similar symptoms as CFS, but do not usually last as long as CFS (1). Management should also occur during this period. A referral to a rheumatologist, neurologist or sleep specialist can made as necessary.
Differentials
The fact that there are many diseases with lethargy as a symptom makes it essential to rule them out before reaching a diagnosis. These include autoimmune disease such as SLE and juvenile rheumatoid arthritis, endocrine disorders such as diabetes and hypothyroidism, congestive cardiac failure, chronic liver disease and chronic renal failure, neuromuscular disease such as multiple sclerosis and myasthenia gravis, malignancies, leukaemia, chronic infection with tuberculosis, hepatitis B/C, HIV/ AIDS and localised infection such as sinusitis. Other causes include parasitic disease such as giardiasis and toxoplasmosis, sleep disorders such as sleep apnoea, narcolepsy, medication side effects, substance abuse and psychiatric disorders (21).
Postural tachycardia syndrome (POTS) involving orthostatic tachycardia without orthostatic hypotension is often found comorbid with CFS. It involves a heart rate increase of greater than 30 beats per minute when patients go from laying down to standing in the absence of other causes of orthostatic hypotension, such as dehydration.
There are increased rates of psychiatric disorders in young people with CFS, with depressive and anxiety disorders being the most commonly reported comorbid problems (21). Central Sensitivity Syndromes involve syndromes sharing the common mechanism of a heightened perception of pain and sometimes triggering abnormal responses. These include CFS, irritable bowel syndrome, chronic headaches and fibromyalgia.
Treatment
Once a diagnosis is made, the physician should provide information on the possible causes and course of CFS.
For example, precipitating factors identified such as physical, infectious and psychological causes and perpetuating factors such as poor sleep, reduced activity causing deconditioning, stress, over exertion.
The patient should be advised that setbacks/relapses are to be expected and may be triggered by unexpected/unplanned activities, poor sleep, infection or stress. A shared decision making should be made regarding the pace of interventions. Engagement with the family is important for young patients.
Treatment plan is individualised based on symptoms, support and educational needs. General management would involve management of symptoms such as pain and dizziness, sleep management, pacing, rest periods, and adjustments to studies or work to help patients return when they are fit enough (22).
Behavioural approaches to help children regulate their activities and improve sleep include Cognitive Behavioural Therapy which challenges unhelpful thoughts about their symptoms, Graded Exercise Therapy (GET) focusing on use of regular physical activity, starting from a little and increasing the duration and intensity over time and Activity Management involving splitting activities into achievable tasks followed by increasing in complexity (23).
A self-modified activity pacing involving patient estimation of current physical and mental capabilities before commencing desired activities in personal care, productivity and leisure as well as graded exercise therapy once patient can control their daily life activities without excessive feelings of fatigue was shown to improve satisfaction and performance in daily life activities (24).
Early in the illness, most children may not be able to attend school. An awareness of how the schools that their patient attend functions is important. For example, as different teachers are scheduled to teach at different times each day, recommending patients to attend at a fixed time daily would not be feasible as it would mean encountering different subjects each day. Instead, it could be better to reduce subjects depending on the child’s career goals, subject preferences and what is needed to progress through schools. Of importance is feeling understood and believed by teachers and doctors about their condition (25).
A plan is needed to be in place for managing setbacks as a result of “push-and-crash” cycles which may involve relaxation and breathing techniques, trying to maintain activity and exercise levels by pacing activities/ alternating activities with breaks. However, in some setbacks/ relapses, it may be required to stop activity and increase rest period to stabilise symptoms and re-establish a new baseline (22). There is a need to plan activity and rest to stay within limits of tolerance or “energy envelope.”