A clinical synthesis based on the Amsterdam 2022 consensus (Patricios 2023, BJSM), the landmark randomised trials (Leddy 2019, Schneider 2014) and the neurometabolic cascade of Giza & Hovda.

What are the fundamentals to know about concussion?

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How is concussion defined and who is most affected?

The sport-related concussion (SRC) is defined by the Amsterdam 2022 consensus as a mild traumatic brain injury induced by biomechanical forces transmitted to the head, neck or trunk. It shows up as the rapid onset of a brief alteration in neurological function, which resolves spontaneously in most cases.¹ SRC is a subset of mild traumatic brain injury (mTBI); the two terms are often used interchangeably, although SRC implies a specific sporting context.

From an epidemiological point of view, contact sports (rugby, ice hockey, American football, boxing, MMA) and sports carrying a risk of falling (cycling, equestrian sports, snow sports) account for the bulk of cases. In adults, around 90 % of SRCs resolve within 14 days ; in adolescents, that period frequently extends to 4 weeks.¹ Longer recovery times have been reported in women and in younger athletes, but the systematic review that informed the Amsterdam 2022 consensus concludes, given the heterogeneity of the studies, that recovery patterns are similar across sex and age.⁴

What happens in the brain? The neurometabolic cascade and natural history

The neurometabolic cascade described by Giza & Hovda (2014, Neurosurgery) is the reference pathophysiological framework.² The biomechanical impact causes axonal stretching and massive neuronal depolarisation with glutamate release, triggering a cascade of ionic events (potassium efflux, sodium and calcium influx) that exhaust ATP reserves. The Na/K-ATPase pumps, called on to restore ionic homeostasis, consume glucose massively, creating a transient metabolic energy crisis contrasting with relative cerebral hypoperfusion.²

This supply-demand mismatch (high metabolic demand with reduced vascular supply) constitutes a window of cerebral vulnerability during which a second impact, even a minor one, can produce disproportionate injury (the concept of second impact syndrome). This window of vulnerability, whose exact duration remains poorly defined in humans, justifies the initial rest from sport and caution in the graded return.²

The natural history is generally favourable, with spontaneous resolution of symptoms within a few days to a few weeks. Beyond one month, symptoms are described as persisting (post-concussion syndrome, PCS), whose pathophysiological mechanisms remain debated (neurometabolic, cervicogenic, vestibular, psychological and central sensitisation components).¹

Which tools should be used to assess a concussion? SCAT6, BESS and cervical tests

The SCAT6 (Sport Concussion Assessment Tool, 6th edition), published alongside the Amsterdam 2022 consensus, is the standardised tool for the acute assessment of SRC and is most useful within the first 72 hours. Beyond that, for assessment in the clinic, the consensus produced a separate tool, the SCOAT6 (Sport Concussion Office Assessment Tool 6).¹ It comprises several sections: immediate recognition (with red flags), symptom assessment (22 items scored 0-6), cognitive orientation, immediate and delayed memory, balance and coordination, and neurological tests. For the public and non-medical staff, the CRT6 (Concussion Recognition Tool 6) provides a simplified guide to recognition and referral.¹

Assessment of balance classically rests on the BESS (Balance Error Scoring System): 3 stances (double-leg stance, single-leg stance on the non-dominant leg, tandem stance with the non-dominant foot behind) on 2 surfaces (firm ground, foam), eyes closed, each for 20 seconds, counting the errors (maximum total 60). The modified BESS (mBESS, 3 stances on firm ground only) is built into the SCAT6.¹

The cervical examination is essential and too often neglected: it includes assessment of active range of motion (flexion/extension, rotations, side flexion), palpation of the suboccipital muscles and trapezius, and the search for reproducible pain suggesting a cervicogenic component. The vestibulo-oculomotor tests (smooth pursuit, horizontal and vertical saccades, vergence, VOR, vestibulo-ocular reflex, gaze stabilisation) complete the assessment and point towards specific rehabilitation where abnormalities are found.¹

How can concussion be told apart from associated conditions (cervicogenic, vestibular)?

SRC is frequently accompanied by associated conditions that must be recognised in order to guide treatment:

• Cervicogenic component : headache of cervical origin, cervicogenic dizziness (triggered by head movements, with altered cervical proprioception), neck pain reproducible on palpation. A full cervical examination (palpation, range of motion, provocation tests) is essential.¹
• Central or peripheral vestibular dysfunction : rotatory vertigo, unsteadiness, abnormalities of the VOR or of gaze stabilisation. The VOMS (Vestibular/Ocular Motor Screening) test is useful for screening.¹
• Oculomotor dysfunction : difficulty reading, eye strain, abnormalities of vergence or saccades.
• Psycho-affective component : anxiety, depression, sleep disturbance, often underdiagnosed but correlated with prolonged recovery.²

This multidimensional characterisation (clinical profiles or phenotypes: cervical, vestibular, oculomotor, cognitive/fatigue, anxiety/mood, migraine) allows targeted management rather than a single standardised treatment.¹

Relative or active rest? What does the research say?

The historical view of prolonged strict rest (« cocooning ») as the reference treatment for concussion is today obsolete. The systematic review by Schneider et al. (2017, BJSM), commissioned for the Berlin consensus, supports a brief period of cognitive and physical rest (24 to 48 hours), after which the patient is encouraged to increase activity gradually; the exact duration of rest has not been established.¹ The review that prepared the Amsterdam 2022 consensus states that an early return to light physical activity and reduced screen time during the first two days safely facilitate recovery, and that strict physical rest until symptoms resolve is not effective.⁵

The proposed mechanism: prolonged rest induces physiological deconditioning, avoidance-related anxiety, sleep disturbance and kinesiophobia which paradoxically prolong symptoms. A return to controlled activity, by contrast, stimulates neurometabolic and psychological recovery.¹

Subthreshold aerobic exercise: the Leddy revolution

The landmark randomised trial by Leddy et al. (2019, JAMA Pediatrics) transformed management by showing that symptom-limited subthreshold aerobic exercise, prescribed as early as 2-10 days after concussion in adolescent athletes, significantly shortens recovery.²

The protocol rests on the Buffalo Concussion Treadmill Test (BCTT) : a graded treadmill exercise test to determine the threshold at which symptoms are exacerbated (heart rate threshold, HRt). The patient is then given aerobic exercise for about 20 minutes a day, at 80 % of the heart rate reached at symptom exacerbation on the BCTT, with the target recalculated each week; the session stops if symptoms increase by 2 points or more out of 10.

Results: the aerobic exercise group recovered in a median of 13 days (interquartile range 10-18.5) against 17 days (13-23) for the stretching group (p = 0.009, Mann-Whitney test), with no adverse events.² Recovery taking 30 days or more was less frequent in the exercise group (4 % vs 14 %), a difference that was not significant (p = 0.08). The trial enrolled adolescents seen within 10 days of concussion: it supports exercise in the early phase, not as a treatment for symptoms that have already become persistent.

Cervicovestibular and oculomotor rehabilitation

The pivotal randomised trial by Schneider et al. (2014, BJSM) demonstrated the added value of combined cervicovestibular rehabilitation in patients with persistent symptoms (neck pain, headache or dizziness) after sport-related concussion.³

Method : 31 patients (12-30 years) with symptoms persisting > 10 days randomised into two groups (intervention vs watchful control). The intervention comprised cervical manual therapy (mobilisations, manipulations), cervical exercises (motor control, endurance), vestibular rehabilitation (habituation, VOR exercises, gaze stabilisation) and balance exercises, over 8 weeks.

Results : 73 % (11/15) of patients in the intervention group were medically cleared to return to sport at 8 weeks, against 7 % (1/14) in the control group (adjusted RR: 3.91 ; 95 % CI 1.34-11.34; p = 0.002). These results, although in a small sample, remain among the most striking in post-concussion rehabilitation and feature in the Amsterdam 2022 recommendations.³

The six-stage return-to-sport protocol

The Berlin 2016 consensus (McCrory 2017) and then Amsterdam 2022 (Patricios 2023) set out a graded return-to-sport (RTP) protocol in 6 stages, each separated by a minimum of 24 symptom-free hours. Any return of symptoms requires going back to the previous stage.¹٬²

The Return to Learn (RTL) always precedes the Return to Play. The pupil or student must be able to tolerate a full school day without symptoms worsening before progressing through the sporting stages. This priority of school and cognitive activity over sport is a strong consensus principle.¹

What are the factors predicting prolonged recovery?

The systematic review by Iverson et al. (2017, BJSM) identifies several factors predicting prolonged recovery after SRC, useful for clinical stratification from the initial assessment onwards:³

• Initial symptom severity (a high symptom score on the SCAT): the most robust predictor.
• A history of previous concussion(s).
• Female sex in adolescence : some evidence of a higher risk of persistent symptoms, with mixed findings.
• Young age (adolescents > adults).
• Personal history : mental health problems (anxiety, depression); pre-existing migraine may play a part, but studies disagree. According to this review, ADHD and learning disabilities do not carry a substantially higher risk.
• Marked initial cognitive or vestibular/oculomotor symptoms.

Identifying these factors early justifies intensified management (prompt referral to a specialist physiotherapist, close follow-up) rather than passively waiting for resolution.³

Two case reports illustrating multimodal management

Case 1: a 24-year-old student athlete, symptoms persisting for 18 months, treated with craniosacral therapy and lymphatic drainage

This case report (Kratz, SAGE Open Medical Case Reports, 2021), written by an occupational therapist, describes a 24-year-old man with symptoms persisting for 18 months after a sport-related concussion. Treatment combined, with no other therapy, craniosacral therapy, manual lymphatic drainage and so-called glymphatic techniques, over eleven sessions in 3 months. The author reports an 87 % reduction in the cumulative Post-Concussion Symptom Checklist score and, at 6 months, a return to studies and to paid employment; no return to sport is reported. A single case, with no control group, does not allow this change to be attributed to the treatment.¹

Case 2: A patient with post-concussion syndrome treated with neuromotor retraining

A second case report (Teare-Ketter et al., Int J Sports Phys Ther, 2021) describes a 21-year-old man seen 356 days after his concussion. Eight 60-minute sessions over five weeks combined low-velocity cervical and thoracic mobilisations, gaze stabilisation and saccade exercises, then neuromotor retraining in sitting with a laser harness used as a postural reference. The RPQ score fell from 20 to 2, with only headache persisting. A single case without a control group cannot attribute this course to the programme.²

These two cases illustrate a consensus principle: managing persistent post-concussion syndrome cannot be one-dimensional. It must simultaneously target the dominant phenotypes identified at assessment (cervical, vestibular, oculomotor, cognitive, anxiety, migraine), with gradual intensification below the symptom threshold.

Critical differential diagnoses not to be missed

Any post-traumatic assessment must consider the critical differential diagnoses, some of which are life-threatening emergencies:

• Intracranial haemorrhage (subdural or extradural haematoma): progressive headache, vomiting, deteriorating consciousness, focal neurological deficit → urgent imaging.
• Subarachnoid haemorrhage : explosive « thunderclap » headache → urgent imaging (non-contrast CT).
• Cervical arterial dissection (carotid or vertebral): violent unilateral neck pain, headache, Horner’s syndrome, ischaemic stroke → MR or CT angiography.
• Cervical fracture with or without spinal cord involvement: pain, stiffness, neurological deficit → cervical immobilisation and imaging.
• Post-traumatic migraine : throbbing headache with possible aura, a history of migraine.
• BPPV (benign paroxysmal positional vertigo) : brief rotatory vertigo triggered by changes in head position → Epley manoeuvre.
• Post-concussion syndrome (PCS): symptoms persisting beyond one month, with no structural lesion.

When to refer urgently? Red flags in concussion

Immediate recognition of the red flags is the first non-negotiable skill of anyone involved (clinician, coach, therapist, pitch-side physiotherapist). Their presence requires immediate removal from play and urgent medical referral (emergency services, hospital emergency department).¹

Beyond the red flags, yellow flags (psychosocial factors) must be looked for: catastrophising, fear of returning to sport, high anxiety, depression, social isolation. Their presence justifies early psychological input, as they predict prolonged recovery and an increased risk of post-concussion syndrome.¹

Measuring outcomes and working in a multidisciplinary team

Standardised outcome measurement is essential. The most widely used validated PROMs are:

• RPQ (Rivermead Post-Concussion Symptoms Questionnaire): 16 items, score 0-64, for longitudinal follow-up.
• PCSI (Post-Concussion Symptom Inventory): versions adapted by age (child, adolescent, adult).
• SCAT6 symptom severity score: built into the SCAT, 22 items × 6 = score 0-132.
• HIT-6 (Headache Impact Test) where headaches predominate.
• DHI (Dizziness Handicap Inventory) where dizziness predominates.

Multidisciplinary collaboration is central: the sports physician (clearance to return to play), the neuropsychologist (cognitive assessment, management of anxiety and depression), the ENT or vestibular specialist (where persistent central or peripheral vestibular involvement is suspected), the occupational therapist (graded return to school or work). The physiotherapist holds a central position in coordinating this pathway, particularly for the cervical and vestibular phenotypes and for the graded return to exertion.¹