Reframing Postconcussional Syndrome as an Interface Disorder of Neurology, Psychiatry and Psychology

Camilla N. Clark; Mark J. Edwards; Bee Eng Ong; Luke Goodliffe; Hena Ahmad; Michael D. Dilley; Shai Betteridge; Colette Griffin; Peter O. Jenkins


Brain. 2022;145(6):1906-1915. 

In This Article

Current Terminology and its Weaknesses

Numerous definitions for mTBI have been published (Table 1).[3–13] The definitions extrapolate the presumed presence and severity of an underlying TBI from clinical markers. Alteration of mental state is considered a fundamental marker of TBI, with classifications agreeing, for example, that loss of consciousness is sufficient (but not necessary) to diagnose a mTBI. However, debate remains regarding the degree of alteration in mental state required, whether evidence of structural injury constitutes a more severe injury and whether the presence of subjective post-injury symptoms (e.g. headache, dizziness, cognitive impairment) is sufficient to diagnose a TBI.

A recent survey of mTBI experts found agreement amongst the panel that individuals with an mTBI can present with isolated subjective symptoms such as headache, dizziness and cognitive impairments.[4] However, such symptoms are not specific to head injury, occurring at the same rate in those with extracranial injury and in up to three quarters of otherwise healthy adults.[14–16] This perhaps explains the finding that 59% of the general population who report having been 'concussed' deny ever having had a brain/head injury.[17]

Despite the lack of specificity of these symptoms to brain injury, the term 'PCS' is widely used to describe the persistence of these symptoms beyond 3 months following mTBI. Perhaps in recognition of this lack of specificity [there was only 40% agreement between the 4th edition of the Diagnostic and Statistical Manual (DSM-4) and 10th edition of the International Classification of Disease (ICD-10) diagnostic criteria for PCS when applied to a large cohort],[18] the latest iterations of the DSM and ICD have removed the category of PCS and subsumed it under 'neurocognitive disorders due to traumatic brain injury' and 'mild neurocognitive disorder' (which can be secondary to trauma), respectively (Table 2).

Unfortunately, the criteria for neurocognitive disorder continue to lack diagnostic precision and focus on non-specific symptoms. The aim should be objective diagnostic measures to help categorize the symptoms within specific diagnoses, that in turn might link to specific treatments. In the differential diagnosis section of neurocognitive disorders due to TBI in DSM-5, the practitioner is advised specifically to consider alternative diagnoses of somatic symptom disorder or factitious disorder to explain the persistent neurocognitive impairment. The Scottish Intercollegiate Guidelines Network (SIGN) for brain injury rehabilitation states: 'In a small minority of mTBI patients, symptoms may be more prolonged, but in such cases the determinants of disability appear to be personal and social factors and not related to the brain injury.[19] This approach results in a clear dualistic split between an (unspecified) physical damage-related mechanism for persistent symptoms and an (unspecified) psychological mechanism. However, as detailed below, a variety of interacting mechanisms for symptoms may exist which span the false divide between 'physical' and 'psychological'.