Periventricular Nodular Heterotopia (PNH)
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.