OBSERVATION Agenesis of the Arcuate Fasciculi in Congenital Bilateral Perisylvian Syndrome A Diffusion Tensor Imaging and Tractography Study Byron Bernal, MD; Gustavo Rey, PhD; Catalina Dunoyer, MD; Harshad Shanbhag, MS; Nolan Altman, MD Objective: To describe the absence of the arcuate fas- Main Outcome Measures: Neuropsychology evalu- ciculi in 2 cases of congenital bilateral perisylvian syn- ation; fractional anisotropy, apparent diffusion coeffi- drome (CBPS). cients, and anatomical aspect of the tracts. Design: Case series. Results: Absence of the arcuate fasciculus was ob- served in both subjects. Ancillary findings were com- Setting: Pediatric referral hospital–based study. plete absence of the superior longitudinal fasciculi in 1 case and underdevelopment in the other. Low fractional Patients: Two patients with CBPS, referred to our anisotropy of the left inferior occipitofrontal fasciculus institution as candidates for surgical treatment of was found in both cases. The same tract was malori- epilepsy. ented in 1 of the cases. Intervention: Diffusion tensor imaging (1.5-T scan- Conclusion: Agenesis of the arcuate fasciculus may ac- ner; 15 encoding directions; b=800 s/mm2) and deter- company CBPS. ministic tractography of the main projection and asso- ciation tracts. Arch Neurol. 2010;67(4):501-505 HE CONGENITAL BILATERAL speech deficit may contribute to the perisylvian syndrome understanding of the arcuate fasciculus (CBPS) is a type of corti- function. cal developmental abnor- mality characterized by Tpoor operculation of the parietal and REPORT OF CASES frontal lobes, wide lateral sulcus, polymi- crogyria, orofacial diplegia, epilepsy, and The clinical and neuroradiological find- developmental delay.1,2 Seizures are pres- ings of 2 cases with CBPS are summa- ent in 65% of cases.3,4 To our knowledge, rized in the Table. Case 2 has no arcuate CBPS has not been studied to date with fasciculus but has the remnant fibers of diffusion tensor imaging and fiber trac- the superior longitudinal fasciculus. tography. Normally, the superior longitudinal fas- We describe 2 cases with absence of ciculus has, in addition to the arcuate the arcuate fasciculus (as part of agenesis fasciculus, a bundle of short fibers con- or hypoplasia of the superior longitudi- necting the parietal areas (supramarginal nal fasciculus) in CBPS using diffusion gyrus) with frontal areas. In addition, the tensor imaging and fiber tractography in fractional anisotropy of the left inferior relation to clinical and neuropsychologi- occipitofrontal fasciculus was found to Author Affiliations: Miami Children’s Hospital (Drs Bernal, cal findings. To our knowledge, there are be low in both cases and bilaterally in Rey, Dunoyer, and Altman and no existing reports describing bilateral the cingulum of case 2. Mr Shanbhag) and MCH Brain agenesis of the arcuate fasciculus in this A single-shot, spin-echo, echo-planar Institute (Drs Bernal, Rey, and condition. The correlation of this finding imaging sequence with diffusion weighting Dunoyer), Miami, Florida. with the clinical analysis of the language/ consisting of 15 encoding directions was (REPRINTED) ARCH NEUROL / VOL 67 (NO. 4), APR 2010 WWW.ARCHNEUROL.COM 501 ©2010 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 Table. Report of Cases Case 1 Case 2 Age, y 13 18 Sex F M Handedness Right Right Main diagnosis Intractable epilepsy; CBPS Intractable epilepsy; CBPS Onset of seizures, y 3 12 Type of seizure Right side head and eye version Right side head version, staring, jaw movements General developmental Motor: normal; poor attention; deficit executive functions Motor: normal, but with sucking and swallowing milestones problems as infant Language developmental Speech severely delayed; poor language comprehension Speech severely delayed; poor language comprehension milestones Neuropsychology evaluation Overall intellectual functioning Moderate to severe impaired range (IQ=41; VCI Mildly impaired (IQ=64; VCI score=82; POI score=67)b score=55; PRI score=49; WMI score=50; PSI score=50)a Language Prosody Poor Poor Articulatory skills Poor Poor Conduit d’approachec None None (not described) Automatic series Normal Normal Automatic series backward Normal Unable Phonemic fluency Severely impaired (standard score Ͻ40)d Moderately impaired (standard score=52) Semantic fluency Borderline (standard score=71) Moderately impaired (standard score=54) Verbal memory Poor, with relatively preserved delayed recall Borderline (scale score=5)e; good delayed recall (scale score=6)e Verbal reasoning Severely impaired (scale score=3)a Borderline (scale score=6)b Nonverbal reasoning Severely impaired (scale score=1)a Impaired (scale score=4)b Constructional praxis Poor (VMI standard score=61; scale score=1)a Borderline (scale score=5)f; very poor graphomotor skills (VMI standard score=45) Auditory working memory Severely impaired (digit span, scale score=1)a Impaired (digit span, scale score=3)b Memory for faces Borderline (scale score=6)g; normal delayed recall (scale Moderately impaired (raw score=7)g; better for delayed score=9)g recall (raw score=10)g Visual psychomotor speed Severely impaired (PSI standard score Ͻ40) Impaired (PSI standard score=57) Fine motor dexterity Severely impaired bilaterally: RH standard score Ͻ40; Severely impaired: RH standard score Ͻ40; LH standard LH standard score=unable to performh score Յ40h Neuropsychological global “Diffuse cerebral dysfunction, with relatively preserved “Multiple cognitive domains impairment with a trend of profile performance on measures associated with greater dysfunction of the nondominant hemisphere mesiotemporal systems” [with] preserved mesiotemporal regions” EEG Interictal: right frontotemporal slowing; ictal: bilateral Interictal: bilateral temporal spikes and right temporal central epileptiform activity slow waves; ictal: bilateral centrotemporal sharp slow waves more prominent in the right side MRI Bilateral opercular cortical malformation; thick cortex, Bilaterally poorly formed operculum; cortical thickening, small gyri, abnormal sulcation (Figure 1A); left polymicrogyria in opercular and hippocampal regions cerebellum hypoplasia (Figure 1B); left cerebellar aplasia DTI/tractography Color-coded FA map: failure to demonstrate the SLF Color-coded FA map: small and poorly defined SLFs bilaterally (Figure 4); bilateral abnormal IOFF (Figure 5); fiber tractography: absence of the arcuate orientation (curved upward); lack of cerebellar fibers fibers (Figure 6) Other associative tracts (FA/ADC) Left IOFF: 0.33i/0.88 Left IOFF: 0.38i/0.85 Right IOFF: 0.53/0.81 Right IOFF: 0.46/0.86 Left ILF and IOFF: 0.48/0.84 Left ILF and IOFF: 0.47/0.94 Right ILF and IOFF: 0.47/0.89 Right ILF and IOFF: 0.52/0.90 Left cingulum: 0.44/0.76 Left cingulum: 0.39i/0.82 Right cingulum: 0.40/0.80 Right cingulum: 0.35i/0.81 Left internal capsule: 0.61/0.80 Left internal capsule: 0.53/0.78 Right internal capsule: 0.55/0.82 Right internal capsule: 0.51/0.82 Abbreviations: ADC, apparent diffusion coefficients; CBPS, congenital bilateral perisylvian syndrome; DTI, diffusion tensor imaging; EEG, electroencephalography; FA, fractional anisotropy; IOFF, inferior occipitofrontal fasciculus; ILF, inferior longitudinal fasciculus; LH, left hand; MRI, magnetic resonance imaging; POI, Perceptual Organization Index; PRI, Perceptual Reasoning Index; PSI, Processing Speed Index; RH, right hand; SLF, superior longitudinal fasciculus; VCI, Verbal Comprehension Index; VMI, Beery-Buktenica Developmental Test of Visual-Motor Integration; WMI, Working Memory Index. a Wechsler Intelligence Scale for Children–Fourth Edition Spanish Version. b Wechsler Adult Intelligence Scale–Third Edition Full-Scale IQ. c Conscious effort to correct mispronunciations. d Multilingual Aphasia Examination Spanish Version. e Wide Range Assessment of Memory and Learning, Second Edition. f Wechsler Adult Intelligence Scale–Third Edition Block Design. g NEPSY Memory for Faces subtest. h Grooved Pegboard Test. i Values lower than normal range accordingly with in-house standardization. (REPRINTED) ARCH NEUROL / VOL 67 (NO. 4), APR 2010 WWW.ARCHNEUROL.COM 502 ©2010 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 A B A P Figure 1. T1-weighted axial magnetic resonance images showing main findings of congenital bilateral perisylvian syndrome. A, Case 1. B, Case 2. Notice the distinctive widening of the sylvian fissure with “exposure” of the insula to the cortical surface and abnormal sulcation. A P Figure 3. Normal appearance of the superior longitudinal fasciculi and the arcuate fasciculi in a normal volunteer. The superior longitudinal fasciculi (double thin arrows), conformed by parietal fibers (arrowheads), and the arcuate fasciculi (long single arrows). The superior longitudinal fasciculi on the right side does not carry arcuate fibers. Red indicates left side; Figure 2. Normal appearance of the superior longitudinal fasciculus (arrows) yellow, right side; A, anterior; P, posterior. in a normal volunteer defined at this level as triangular green shapes lateral to the blue descending fibers of the corticospinal tract. COMMENT performed in a 1.5-T scanner (Figure 1). A diffusion weighting (b) of 800 s/mm2 was used. Fractional anisot- The superior longitudinal fasciculus consists mainly of ropy and tractography was performed using Volume- the long curved fibers with posterior end points in the One software (http://www.volume-one.org/).