Impact of Epilepsy on cognition
IQ is reduced
When compared to TD & sibling (Bailet and Turk 2000)
The gap persists over time and they fall further behind
Reduced cognition in Epilepsy is associated with:
Early age onset
Drug resistant
Structural brain lesion
Prevalence of language disorders in Epilepsy & Structural Epilepsy
- 30-42%
- 67% in structural epilepsy
Type of Language Impairment in Epilepsy
- Over-generalisation of grammatical rules
- Limited vocabulary
- Anomia
- Bizarre sentence formation
- Inability to adjust linguistic style
As children get older language difficulties become more severe
What is Anomia
A type of language deficiency in Epilepsy
a type of aphasia where an individual has consistent inability to produce words for things that they want to talk about (particularly nouns and verbs). Anomia is a deficit of expressive language.
Brain areas used to Semantic Processing
Ventral: Fronto temporal
Semantic Processing
Brain areas used to Sensory-motor Processing
Dorsal: Fronto parietal
Sensory-motor processing
WM tracts associated with language
Tracts:
- Uncinate Fasciculus
- Extreme Capsule
- Arcuate Fasiculus
Uncinate Fasciculus connects:
Inferior Frontal Gyrus orbitofrontal area & limbic areas in the anterior Temporal areas such as hippocampus & amygdala
Extreme Capsule Connects:
Bidirectional between:
- claustrum & the insular cortex,
- inferior frontal gyrus (Broca’s area) middle-posterior portion of the superior temporal gyrus (Wernicke’s area)
Arcuate Fasiculus connects
caudal temporal cortex & Inferior Parietal lobe Frontal lobe
Language WM development
A prolonged development across childhood
1) Ventral: present at birth and grows
2) Dorsal: matures at approx. 8 years old
3) Inter-henmispheric connection - mature earlier than intra-hemispheric connections
Dorsal Language Stream development
Dorsal: Fronto-parietal
Sensory-motor processing
Matures throughout childhood - peak @ 7 years old
Ventral Language Stream development
Ventral: Fronto-temporal
Semantic Processing
Present at birth and grows throughout life
When does lateralisation develop?
relatively fixed by age 5
however research is INCONCLUSIVE: Low specificity & Low sensitivity of studies
Lateralisation research
Review:
Has low specificity & Sensitivity
Most studies are underpowered and therefore not picking up effect
Development of regions associated with semantic processing:
Increased activation: >L. Broca’s area >R & L Middle Temporal gyrus >L &R. Inferior temporal gyrus >R&L. Pars orbitalis
Impact of childhood onset TL Epilepsy on Language WM network
- Widespread WM changes
- Early developing inter-hemispheric connect is compromised
- -> Posterior CC
- -> Cingulum
Associated with poorer IQ & Memory & Fluency
Epilepsy & Grey Matter network
Poorer language is associated with localised reductions in:
> iFG and posterior STG
> Anterior STG
When compared to children with epilepsy but no LI
Epilepsy impact on Ventral & Dorsal language network
Ventral network = reduced activation
- early developing ventral network is vulnerable
- -> 47% of the variance & 8% in controls
Dorsal Network = increased (Trend)
- related to better task performance
% of atypical Language Lateralisation
higher % of atypical lateralisation
30-60%
Atypical language re-organisation associated with:
>Earlier age of onset of seizures/lesion >left perisylvian seizure focus >Atypical handedness >Normal MRI >Having a Stroke >Lesions in anterior language regions
Atypical language lateralisation is not associated with
Intra-hemispheric difference - they use the same network
Atypical Intra-hemispheric language re-organisation can be associated with:
Intra-hemispheric re-organiation predicted by lesions in Broca, Wernick or handedness
- but atypical lateralisation was not linked to intra hemispheric lesions to broca or wernick
