To the Editor: Attention-deficit hyperactivity disorder (ADHD) is characterized by deficits in attention, with impulsivity and motoric hyperactivity, and it may have predominance of either inattention or hyperactivity or have a mixture of both. ADHD patients have a core problem of being unable to delay or inhibit a response, which is considered to be a central executive function, and one of the structures modulating this is the cerebellum.1 Various studies have already pointed toward cerebellar deficits in ADHD, and vermal volume was consistently found to be significantly less in children with ADHD.2
The coinage Dandy-Walker (DW) Complex comprises three entities: Dandy-Walker malformation, Dandy Walker variant, and the megacisterna magna, of which the Dandy-Walker variant consists of cerebellar dysgenesis without posterior fossa enlargement, along with variable degree of cerebellar vermis hypoplasia.3 Cerebellar hypoplasia has been reported to be associated with multiple features in subjects, for example, mental retardation, autism, childhood-onset schizophrenia, and so on.4 Nonetheless, the interesting association of Dandy-Walker Complex and ADHD could be a rare clinical entity. In fact, a PubMed search revealed only two such case examples: In the first report, ADHD was noted in a 13-year-old boy who had Pascual-Castroviejo syndrome that included Dandy-Walker Malformation.5 The second case report described ADHD in a 14-year-old adolescent patient who had Dandy-Walker Variant and intellectual disability.6 We present the case of a 5-year-old child who had a constellation of seizures, ADHD, and intellectual disability in the backdrop of a Dandy-Walker variant pathology.
A 5-year-old boy with no significant family history; past history of delayed birth cry; delayed speech, social, adaptive, and intellectual functioning, presented to our outpatient department with attacks of seizure since the age of 1 year. The attacks would begin with localized sweating in forehead, followed by a brief period of blank stare in which he became unresponsive to and unaware of his surroundings, and subsequently had loss of consciousness, uprolling of eyeballs, tonic–clonic jerks of the limbs, aversive head movement to right side, incontinence of urine, and post-ictal lethargy.
Along with the above, our patient was noted to have features of marked hyperactivity, poor attention, and impulsive behavior since the age of 3 years, which made it difficult for him to attend school or play meaningfully with his peer-group. He was clinically diagnosed as a case of Cryptogenic Localization-related epilepsy, with ADHD and mild mental retardation.
Investigations revealed abnormal EEG, showing generalized spike and slow waves throughout the tracing, once suggestive of electrical status, and, in another record, left temporo-frontal spike slow waves occurring randomly, lasting about 1 second, when EEG was repeated later on. A CT scan of brain showed inferior fourth ventricle communicating with a posterior fossa cyst through widened vallecula of inferior surface of cerebellum, and a prominent fourth ventricle was noted, based on which an impression of Dandy-Walker Variant was made. Psychological and behavioral assessment showed a developmental age (DA) of 48 months, developmental quotient (DQ) of 50, as per Developmental Screening Test, and Social Age (SA) of 54 months and Social Quotient (SQ) of 57, as per the Vineland Social Maturity Scale. A Conner’s ADHD rating revealed a score of 26, which was above the cutoff of 15 for diagnosis of the disorder. Blood biochemistry reports were unremarkable.
He had earlier been treated with phenobarbitone 30 mg/day, but his hyperactivity was aggravated after taking the medicine, so it was gradually tapered off, and carbamazepine was added and slowly built up to a dose of 600 mg/day, along with clobazam in a dose of 15 mg/day and olanzapine 7.5 mg/day. The boy became seizure-free with this combination. He had already been started on olanzapine to control hyperactivity before a final diagnosis of ADHD was made. He was also subjected to a structured activity scheduling, taught self-help skills, and given specific tasks to improve attention, and reinforcements were used for tackling his hyperkinesis. With the above combined regime of psycho-behavioral and pharmacological therapy, the child showed significant response in his target symptoms (Conner’s score coming down to 13 after 3 weeks) and an improved overall quality of life as per his guardian’s account.
The case so described provided for an absorbing study. The patient had a multitude of clinical presentations, including intellectual disability, epilepsy, and ADHD.
The earlier cases reporting the psychiatric comorbidities of DW variant had adolescent subjects,6 whereas our patient was a child. Also, the pattern of comorbidity in our case included seizures, ADHD, and intellectual disability, whereas the earlier cases had conduct disorder, enuresis, and stereotypic movements.
The structural abnormality of Dandy-Walker variant involving the inferior cerebellum seems to be of significance in our patient. Researchers7 have postulated a “developmental chronometry hypothesis,” in which a brain area that develops over a protracted period of time is more vulnerable to various potential hypoxic, toxic, traumatic, and other types of insults, as compared with those areas that develop over a relatively quicker period. Both the cerebellum and prefrontal cortex are two such areas and are important for motor functions and attention aspects of the subject, which are disturbed in ADHD patients. Both have intricate internal connections of functional neural networks and thus have important biological underpinnings in our case.8
In our case example, Dandy-Walker Variant was also associated with seizure. It was noted that epilepsy associated with cerebellar malformations was usually focal, most often with a temporal lobe focus.9 It is to be noted that, in our case illustration, EEG revealed left temporo-frontal epileptiform discharges.
Another peculiarity was that the subject developed seizures at the age of 1 year, but his ADHD was noted from around the age of 3. This contrasts somewhat with the observation by Hermann and colleagues,10 who noted that ADHD and its complications antedate the onset of seizures in 82% of cases; perhaps this variance could be partly explained by the additional presence of a structural brain defect in our patient.
We successfully managed the case with behavior therapy after a discussion with the child’s mother. Full control of seizures and probably olanzapine also contributed to the overall clinical improvement.
In conclusion, our case example adds to the existing body of literature documenting a psychiatric comorbidity pattern in a child with Dandy-Walker Variant. It also demonstrated that behavioral therapy can be successfully applied to manage ADHD in Dandy-Walker Variant with comorbid epilepsy and intellectual disability.