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Abstract and Introduction
Abstract
It is time to stop using the term concussion as it has no clear definition and no pathological meaning. This confusion is increasingly problematic as the management of 'concussed' individuals is a pressing concern. Historically, it has been used to describe patients briefly disabled following a head injury, with the assumption that this was due to a transient disorder of brain function without long-term sequelae. However, the symptoms of concussion are highly variable in duration, and can persist for many years with no reliable early predictors of outcome. Using vague terminology for post-traumatic problems leads to misconceptions and biases in the diagnostic process, producing uninterpretable science, poor clinical guidelines and confused policy. We propose that the term concussion should be avoided. Instead neurologists and other healthcare professionals should classify the severity of traumatic brain injury and then attempt to precisely diagnose the underlying cause of post-traumatic symptoms.
Introduction
As neurologists, we often see patients who have persistent neurological problems after head injuries. Many of us are happy to reassure them that they have had a concussion and are suffering from transient 'postconcussion syndrome'. These labels provide reassurance, both to the neurologist and patient, that the injury is benign and reinforce the view that nothing can be done to help. But what does concussion mean, and is such therapeutic nihilism justified? Although a 'light touch' to mild traumatic brain injury (TBI) is often appropriate, many patients go on to have persistent problems that would benefit from more precise neurological assessment.
TBI is a common problem. There are estimated to be at least 1 million emergency department attendances each year in the UK due to head injuries, 90% of which have been considered to be mild. Mild TBI is often considered relatively harmless. The assumption is that any neurological dysfunction is short-lived, usually in the region of minutes. However, long-term effects can be surprisingly common. The resolution of obvious confusion is often followed by a constellation of symptoms that include headache, dizziness, fatigue, irritability, reduced concentration, sleep disturbance, memory impairment, anxiety, sensitivity to noise and light, blurred vision and depression. Most patients suffering a mild TBI recover in the first 3 months, but a significant minority (up to a third) report symptoms persisting beyond 6 months. The presence of a more severe initial injury, pre-existing psychological problems, older age, female sex and previous head injuries all increase the likelihood of persistent symptoms. In addition, involvement in a compensation claim can also be a significant factor in perpetuating symptoms.
TBI can also lead to long-term effects including epilepsy and neurodegeneration. There is an increased risk of Alzheimer's disease, Parkinson's disease and chronic traumatic encephalopathy. Since the early 20th century, repetitive brain trauma sustained from boxing was recognised to produce a progressive neurological deterioration. Originally termed 'dementia pugilistica', there has recently been renewed interest in what is now termed chronic traumatic encephalopathy, a condition defined by neuropathological findings including the presence of neurofibrillary tangles in the depths of sulci. Epidemiological studies also show increased mortality rates even after mild TBI. One large cohort study tracked patients with TBI of all severities attending emergency departments in Glasgow, UK, in 1995 and 1996. Thirteen years after injury the mortality rate of the group had reached over 40%, with increased mortality even in young patients after mild TBI (~15 vs 2 per 1000 per year in community controls). This did not simply reflect non-specific lifestyle factors associated with those exposing themselves to likely injury, as patients with mild TBI had higher mortality rates than those with other types of injury.
There are obviously important questions to answer about the way mild TBI is managed and the extent that patients need to be followed-up. There is confusion about acute assessment and treatment, as well as uncertainty about the prevalence of neurodegenerative complications and the 'dose' of TBI needed to produce them. We need clinical research to answer these questions, and clear guidelines about the acute management of mild TBI. Both of these goals are hampered by the confusion that surrounds the use of the term concussion.
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