Biological correlates of attention deficit hyperactivity disorder and specific learning disability, following stroke in a young child.

Sir,

Stroke or cerebrovascular vascular accident in children is a rare entity, the incidence being 1.2–13/100,000 children under 18 years of age.[1] As per studies, up to 66% of children with a stroke encounter difficulties due to persistent neurological deficits or developed poststroke seizure, learning difficulties.[234] Studies have found that as many as 46% of children who had a stroke develop attention deficit hyperactivity disorder (ADHD).[56] There is a paucity of literature attempting to correlate specific lesions in the brain with ADHD symptoms. The recent studies point that ADHD results from multifaceted morphological alterations in a complex network of brain regions rather than dysfunction of discrete brain regions.

Initial investigations which attempted to find structural correlates of ADHD pointed toward frontostriatal circuitry; however, it has since become clear that other regions of the brain may exhibit morphological alterations including areas of the cerebellum and temporoparietal lobes,[7] basal ganglia, and corpus callosum.[8] There are also certain correlations of structural anomaly of amygdala and thalamus with ADHD.[910] Specific learning disability (SLD) has a strong neurobiological basis. Patients with reading disorders have inactivation of left inferior frontal cortex, left temporoparietal cortex, and left temporo-occipital cortex with hyperactivation of corresponding cortical regions of right hemisphere which seems to be a compensatory effect.[11] Dominant hemisphere (left cerebral hemisphere) being the primary locus of phonological and lexical processing which was affected in our patient and might have attributed to patient's current psychiatric manifestations. Patients with writing disorder and dyscalculia have involvement of parietal lobe, cingulate cortex, temporal and frontal lobe.[11]

This case illustrates a 17-year-old male who presented with complaints of poor academic performance with difficulties in reading, writing, arithmetic skills, and making frequent spelling mistakes for nearly 12 years. He also had a history of hyperactivity, inattention, and impulsive behavior, approximately from the age of 6 years. History revealed that multiple episodes of transient ischemic attacks within 1 month which were characterized by sudden onset giddiness, blurred vision, ataxic gait, and focal neurological deficits at the age of 5 years. The initial three episodes resolved spontaneously within 3–6 h without any sequel, so no medical help was sought for the first them. The child then developed a stroke for which medical opinion sought and was characterized by left ataxic hemiparesis and left upper motor neuron facial palsy. Magnetic resonance imaging of brain had revealed the involvement of both anterior and posterior circulation with acute infarct in bilateral deep temporal, parietal, and thalami with chronic infarcts in bilateral cerebellar hemispheres. Magnetic resonance angiography and venography were unremarkable. The cardiac status and coagulation profiles were normal. He was treated conservatively for stroke and had improved without any focal neurological deficits. Family history was not significant. The child had a normal birth and developmental history with all milestones being achieved at appropriate ages. After detailed clinical evaluation (on Conners rating scale for ADHD) and psychometric assessment (NIMHANS battery for SLD), child was diagnosed with specific learning disabilities (mixed disorders of scholastic skills) with ADHD and was treated with methylphenidate 20 mg/day with significant improvement in the symptoms of ADHD. However, the symptoms of SLD had persisted for which cognitive remediation was suggested.

Various psychiatric disorders are seen in children after stroke. The children with focal stroke lesions provide a potentially useful model for the investigation of psychiatric disorders after brain injury. The involvement of specific brain regions might also provide insight into pathogenesis of psychiatric disorders. Our patient had ADHD which is the most common psychiatric comorbidity with SLD may be due to overlapping neurobiological phenomenon.

SLD is very difficult to be diagnosed before the age of 6 years; however, ADHD can be easily diagnosed before the age of 6 years. In our patient, as the symptoms of ADHD and SLD were noticed simultaneously after the cerebrovascular accident, it can be said that they might be the sequelae of stroke. Patients with stroke may have a several type of language disturbances such as – aphasia, alexia, acalculia, or agraphia. They can exist together or in different combinations.[12] Children with left hemisphere stroke have a large discrepancy in the verbal IQ and performance IQ; however, in our case, there was no major difference in the performance and verbal IQ.[13] The reading difficulties following stroke, mostly have ocular cause,[14] however, in our patient, it was of nonocular cause.

Neurobiology of developmental disorders is a potential area of research. More biological research is needed to establish the accurate association of lobar pathology with psychopathology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.