The exact incidence and prevalence is unknown. It is most commonly seen in amateur and professional sports players where head contact is common (e.g. boxing, American football, rugby, ice hockey), as well as in military personnel exposed to explosive blasts 1,3.
Symptoms have an insidious onset, most often years after the initial injuries, with loss of normal attention, concentration and memory. This can progress, in some cases in 2-3 years, to include motor symptoms such impaired gait, impaired, executive function, lack of insight and poor judgement 1,2,4.
There is generalised cerebral atrophy with more pronounced atrophy of the frontal and temporal lobes (including mesial temporal lobe) as well as the thalamus, hypothalamus and mammillary bodies. A cavum septum pellucidum may be present 2.
CTE is characterised by the presence of neurofibrillary tangles and TDP-43 binding protein in subcortical and perivascular regions, often with reactive astrocytes and microglia 7.
Although the details remain to be elucidated, there is mounting evidence that reactive gliosis and redistribution of aquaporin 4 molecules, leading to disruption of transparachymal CSF clearance of interstitial beta-amyloid via the glymphatic system may be a key component 8.
Imaging features of CTE are nonspecific but the following may be seen 4,7
- generalised cortical atrophy
- hippocampal atrophy
- vermian atrophy
- cavum septum pellucidum
- features of diffuse axonal injury (e.g. microhaemorrhages)
There is clinical and imaging overlap of CTE with other neurodegenerative diseases, and traumatic brain injury is a risk factor for their development (i.e. not just CTE) and should be considered in the differential diagnosis 5,6:
History and etymology
This syndrome was first recognised in boxers in 1928, and has been known as "punch drunk" and "dementia pugilistica".
Neurodegenerative diseases are legion and their classification just as protean. A useful approach is to divide them according to underlying pathological process, although even using this schema, there is much overlap and thus resulting confusion.
neurodegenerative MRI brain (an approach)
- measurements and ratios
- midbrain to pons area ratio (for PSP)
- Magnetic Resonance Parkinsonism Index (MRPI) (for PSP)
- frontal horn width to intercaudate distance ratio (FH/CC) (for Huntington disease)
- intercaudate distance to inner table width ratio (CC/IT) (for Huntington disease)
- scoring systems
- measurements and ratios
- typical/classical Alzheimer disease
- variant (e.g. posterior cortical atrophy)
- chronic traumatic encephalopathy (CTE)
- corticobasal degeneration
- frontotemporal lobar degeneration (FTLD) (not all are tau)
- Pick disease
- progressive supranuclear palsy (PSP)
- Alzheimer disease
- cerebral amyloidosis
- spinocerebellar ataxias
- Huntington disease
- hereditary spastic paraplegia
- amyotrophic lateral sclerosis (ALS)
- clinically unclassifiable parkinsonism (CUP)
- Unverricht-Lundborg disease
- prion diseases (not always included as neurodegenerative)
- 1. McKee AC, Cantu RC, Nowinski CJ et-al. Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury. J. Neuropathol. Exp. Neurol. 2009;68 (7): 709-35. doi:10.1097/NEN.0b013e3181a9d503 - Free text at pubmed - Pubmed citation
- 2. Baugh CM, Stamm JM, Riley DO et-al. Chronic traumatic encephalopathy: neurodegeneration following repetitive concussive and subconcussive brain trauma. Brain Imaging Behav. 2012;6 (2): 244-54. doi:10.1007/s11682-012-9164-5 - Pubmed citation
- 3. Stern RA, Daneshvar DH, Baugh CM et-al. Clinical presentation of chronic traumatic encephalopathy. Neurology. 2013;81 (13): 1122-9. doi:10.1212/WNL.0b013e3182a55f7f - Free text at pubmed - Pubmed citation
- 4. Costanza A, Weber K, Gandy S et-al. Review: Contact sport-related chronic traumatic encephalopathy in the elderly: clinical expression and structural substrates. Neuropathol. Appl. Neurobiol. 2011;37 (6): 570-84. doi:10.1111/j.1365-2990.2011.01186.x - Free text at pubmed - Pubmed citation
- 5. McKee AC, Stern RA, Nowinski CJ et-al. The spectrum of disease in chronic traumatic encephalopathy. Brain. 2013;136 (1): 43-64. doi:10.1093/brain/aws307 - Free text at pubmed - Pubmed citation
- 6. Washington PM, Villapol S, Burns MP. Polypathology and dementia after brain trauma: Does brain injury trigger distinct neurodegenerative diseases, or should they be classified together as traumatic encephalopathy?. Exp. Neurol. 2015; . doi:10.1016/j.expneurol.2015.06.015 - Pubmed citation
- 7. Lucke-Wold BP, Turner RC, Logsdon AF et-al. Linking traumatic brain injury to chronic traumatic encephalopathy: identification of potential mechanisms leading to neurofibrillary tangle development. J. Neurotrauma. 2014;31 (13): 1129-38. doi:10.1089/neu.2013.3303 - Free text at pubmed - Pubmed citation
- 8. Iliff JJ, Nedergaard M. Is there a cerebral lymphatic system?. Stroke. 2013;44 (6, Supplement 1): S93-5. doi:10.1161/STROKEAHA.112.678698 - Free text at pubmed - Pubmed citation