*4.3.2 Cognitive deficits/intellectual disability (ID), behavioural, attentional and socialization defects*

The ID that occurs in severe CP is a consequence of mainly the cerebral cortical injury with injury to the basal nuclei, thalamus and cerebellum playing an additional role [49]. Intellectual retardation almost invariably accompanies the diffuse variety of selective neuronal necrosis (SNN) in severe NE/HIE in term infants [49]. In preterm infants, intellectual function is more severely affected (significantly lower intelligence quotients [IQ ]) in those with spastic quadriplegia than spastic diplegia [32]. In the PVL of encephalopathy of prematurity, more severe lesions with lateral extension into the centrum semiovale and corona radiata would be expected to affect upper extremities in addition (spastic quadriplegia) and intellectual functions as well [32]. The primary white matter injury in encephalopathy of prematurity leads to secondary dysmaturation of grey matter structures with widespread reduction in cerebral volumes (cerebral cortex, deep nuclear grey matter, hippocampus, total cerebral tissue and cerebellum) [32]. White matter injury also underlies the deficits in executive function, behavioural disturbances and socialization deficits and partly explains why language delay, Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) may accompany CP especially in children born prematurely [32]. Hyperactivity and inattention may in part be due to involvement of neurons of the reticular activating system (RAS), the basal nuclei or the cerebellum [32].

*Aetiology and Pathophysiology of Cerebral Palsy DOI: http://dx.doi.org/10.5772/intechopen.106685*

### *4.3.3 Visual abnormalities/squints and cortical visual impairments*

Ptosis, oculomotor and gaze abnormalities result primarily from disturbance or injury to brainstem cranial nerve (CN) nuclei (CN III, IV, VI, VII). in the deep nuclearbrainstem variety of SNN associated with severe and abrupt hypoxic-ischaemic insults in term infants. Severe diffuse cortical necrosis (SNN) involving the visual or occipital cortex underlies impairment of cortical visual functions in children with CP since many of them have cerebral cortical atrophy [49]. Nevertheless, in prematurity, visual impairment could be a consequence of retinopathy of prematurity or injury to white matter visual pathways (PVL) (cerebral visual impairment [CVI]) [32]. PVL is strongly associated with visual impairment since the principal area of injury includes the optic radiations (geniculocalcarine tracts) and visual association areas [32]. This implies that more severe PVL with more extensive lesions involving the peritrigonal white matter, optic radiations and occipital cortex correlates with poorer future vision [32].

### *4.3.4 Hearing and speech deficits, feeding difficulties and undernutrition*

Brainstem CN nuclear involvement in severe NE/HIE underlies the accompanying feeding difficulties due to poor coordination and impairments of sucking (CN V), swallowing (CN IX & X) and tongue movements (CN XII) [49]. It is also possible that in addition to the nuclear injury (bulbar palsy), corticobulbar disturbance (pseudobulbar palsy) contributes to these deficits [49]. The ultimate consequences of the feeding difficulties in young children with CP are undernutrition and stunting unless alternative means of feeding like gastrostomy are employed. However, some well-fed non-ambulatory children with CP may become overweight due to the imbalance between energy intake and utilization.

Oral-motor-dysfunction (from bulbar and or pseudobulbar palsy) causes speech deficits due to weakness and poor coordination of the muscles innervated by CN V, VII, IX, X and XII that are involved in speech and phonation. Injury to the dorsal cochlear nuclei and or cochlea, superior olivary nucleus and inferior colliculus result in hearing deficits in CP [49]. Free or unconjugated bilirubin damages the brainstem auditory nuclei and auditory nerve (bilirubin neurotoxicity) in auditory neuropathy spectrum disorders with or without sensorineural hearing loss (ANSD). This explains the common co-morbid sensorineural deafness in dyskinetic CP secondary to chronic bilirubin encephalopathy (Kernicterus spectrum disorders) [56, 57].

#### *4.3.5 Musculoskeletal problems, gait abnormalities and pain*

The musculoskeletal pathology such as muscle shortening/contracture, bony torsion, joint instability, premature degenerative arthritis in weight-bearing joints are secondary to the integrated effects of the positive and negative features of the UMN syndrome in CP [67, 68]. These musculoskeletal problems and the resultant gait abnormalities and pain are progressive as they worsen over time without early intervention [67, 68]. As children with CP grow, the growth of bone outpaces that of the skeletal muscle resulting in contractures such as gastrocnemius contracture and planter flexed or equinus gait [67, 68]. Thus juveniles develop scoliosis, hip dislocation/subluxation, and fixed contractures as growth spurts occur [67, 68]. Immobility contributes to the pathogenesis of the musculoskeletal abnormalities and explains in part the increased frequency of orthopaedic complications in children with severe

gross motor dysfunction or non-ambulatory CP (spastic quadriplegia/Gross Motor Function Classification [GMFCS] levels IV/V) [67, 68].
