Friday, March 11, 2005

Periventricular Nodular Heterotopia (PNH)

B. S. Chang, MD, J. Ly, BA, B. Appignani, MD, A. Bodell, MS, K. A. Apse, ScM, R. S. Ravenscroft, BA, V. L. Sheen, MD, PhD, M. J. Doherty, MD, D. B. Hackney, MD, M. O’Connor, PhD, A. M. Galaburda, MD and C. A. Walsh, MD, PhD. Reading impairment in the neuronal migration disorder of periventricular nodular heterotopia. Neurology 2005; 64: 799-803.

From the Division of Neurogenetics (Drs. Chang, Sheen, and Walsh, A. Bodell, K.A. Apse, and R.S. Ravenscroft), Behavioral Neurology Unit (Drs. O’Connor and Galaburda, J. Ly), and Howard Hughes Medical Institute (Dr. Walsh, A. Bodell), Department of Neurology, and Division of Neuroradiology (Drs. Appignani and Hackney), Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, and Swedish Neuroscience Institute (Dr. Doherty), Epilepsy Center, Seattle, WA.

Address correspondence and reprint requests to Dr. B.S. Chang, Department of Neurology, Beth Israel Deaconess Medical Center, NRB 02-268B, 77 Ave. Louis Pasteur, Boston, MA 02115.

Objective: To define the behavioral profile of periventricular nodular heterotopia (PNH), a malformation of cortical development that is associated with seizures but reportedly normal intelligence, and to correlate the results with anatomic and clinical features of this disorder.

Methods: Ten consecutive subjects with PNH, all with epilepsy and at least two periventricular nodules, were studied with structural MRI and neuropsychological testing. Behavioral results were statistically analyzed for correlation with other features of PNH.

Results: Eight of 10 subjects had deficits in reading skills despite normal intelligence. Processing speed and executive function were also impaired in some subjects. More marked reading difficulties were seen in subjects with more widely distributed heterotopia. There was no correlation between reading skills and epilepsy severity or antiepileptic medication use.

Conclusion: The neuronal migration disorder of periventricular nodular heterotopia is associated with an impairment in reading skills despite the presence of normal intelligence.


Sped said...

I am a Director of Special Ed with a student having PNH. What is the best way to teach him reading?

Barb Scola

Anonymous said...

I have radiologically confirmed periventricular nodular heterotopia, as do many others in my family. I do not have reading impairment, nor does my affected son. In neuropsych testing, it was actually his GREATEST strength. He has relative deficits in other areas.
Several of my family members with PNH do have reading impairment. Some have "classic" dyslexia that is indistinguishable from that caused by any other underlying problem. Some are more severely impaired. One of my adult nephews is completely unable to read in spite of intensive efforts to teach him. He cannot even learn the alphabet because he confuses letters such as b and d. Yet he holds a steady job, is self supportive, productive, and responsible.
In short, children with PVNH are widely variable in their learning ability, areas of weakness, and areas of strength. It is helpful to realize that if there is something that a child is simply "not getting", there may actually be a biological disruption in the area of the brain which controls that particular function. Teaching efforts may have to focus on developing the child's compensatory strengths. I am familiar with the study on PVNH and reading deficits, and there are a few things that stood out to me. First of all, the study was very small. 10 individuals. It is difficult to get a generalized picture of ability from sample of that size.
Secondly, generalizations in general can be dangerous. Because of my son's exceptional reading skills, some of his exceptionally weak areas were missed until he had a comprehensive evaluation.
PVNH can disrupt normal brain activity, but not always, and not necessarily reading ability.