NeuroSPECT Results, FRONTAL AND TEMPORAL LOBE DYSFUNCTION IN AUTISM AND OTHER RELATED DISORDERS: ADHD AND OCD

FRONTAL AND TEMPORAL LOBE DYSFUNCTION IN AUTISM AND OTHER RELATED DISORDERS: ADHD AND OCD

NeuroSPECT Results

Quantitative rCBF measurements with Xenon 133 were found to be significantly higher than normal in autistic children, with maximal values in the frontal lobes and visual cortex. Minimal perfusion was observed in the temporal lobes. Decreased flow was also noted in the cerebellum and occipital lobes.

The areas of increased perfusion, most frequently located in lateral frontal lobes, are similar to our observations in obsessive compulsive disorder (OCD children). Tc 99m HMPAO images (Prado et al.) demonstrate increased frontal perfusion, and demonstrating also temporal, occipital and cerebellar hypoperfusion. Figure 1.

Figure 1 (click=zoom)

In children with OCD there is a significant increase in frontal perfusion observed bilaterally in a large number (~ 81%) of the children and unilaterally in a limited number (6%) of the children, with a total of 87% of children demonstrating increased frontal perfusion. Among 50% of these children there is also increased perfusion in the posterior cingulate gyrus. Of note, there is furthermore hypoperfusion of temporal lobes mostly in the mesial aspects in 93% of OCD children examined to date.( Mena et al)

Increased frontal perfusion was also reported (Rubin et al.) in adults. Most probably this phenomenon denotes a co-morbidity phenomenon also that is clinically observed between autism and obsessive compulsive disorder.

Discussion of NeuroSPECT Results

NeuroSPECT scans are becoming extremely informative, as they show blood flow through areas of the brain. Blood flow implies function / activity (24)(25). As noted, the autistic children have presented consistently with a decrease in blood flow in the temporal area, various degrees of hypoperfusion in the parietal / occipital area and the cerebellum vermis. There has often been an increase of blood flow in the frontal lobes which is consistent with ADD on the hyperactivity end. Figure 2.

Figure 2 (zoom= click)

The clinical implications of these findings has been heightened by the fact that the "anatomic" areas of the brain involved on the NeuroSPECT have correlated with predicted areas of dysfunction when reviewed by neuro-anatomists (research work in progress). In fact, the areas of dysfunction on Neuro-SPECT, have helped explain readily the physiologic dysfunction of these children.

These children present with a symptomatology consisting primarily of severe speech and language development (Left temporal lobe) and severe social difficulties (Right temporal lobe), often some fine, not usually gross, motor difficulties (cerebellar involvement), and various learning difficulties and attention deficit dysfunctions consistent with involvement of frontal and temporal lobes, and links to areas of parietal-occipital dysfunction. They may also have many symptoms consistent with OCD characteristics, associated with these areas of dysfunction.

In 1995, Mountz, Tolbert, Lill, Katholi and Liu reported their HMPAO findings in 6 children with severe autism and demonstrated with semi-quantitative techniques temporal and parietal hypoperfusion with lateralization to the left hemisphere, while in two of the three images published there is a maximal perfusion in the lateral frontal lobes.

Georges, Costa, Coniz, Ring and Ell reported in four autistic adults with Tc-99 HMPAO diminished rCBF in temporal and frontal lobes. The temporal abnormality appears to be confirmed mostly in adults, adolescents, and children suffering of autism. Thus, damage to temporal lobe in an early developmental stage may result in autistic manifestations.

The results are otherwise heterogeneous translating the heterogeneity of the autistic population, denoting the presence of occipital hypoperfusion and cerebellar hypoperfusion mostly in the mesial aspects corresponding to the vermis area. This later observation correlates with reports in the literature of atrophy of the cerebellar vermis demonstrated by MRI technique. Further heterogeneity in our group of patients is demonstrated by apparent comorbidity with OCD (and ADHD) in these children and their typical presentation of increased perfusion in lateral frontal lobes. (Figure 3)

Figure 3 (click=zoom)