Child's Nervous System

, Volume 28, Issue 6, pp 905–909

Polymicrogyria: correlation of magnetic resonance imaging and clinical findings

Authors

    • Department of Radiology, Faculty of MedicineErciyes University
  • Abdulhakim Coskun
    • Department of Radiology, Faculty of MedicineErciyes University
  • Huseyin Per
    • Department of Pediatrics, Faculty of Medicine, Division of Pediatric NeurologyErciyes University
  • Halil Donmez
    • Department of Radiology, Faculty of MedicineErciyes University
  • Sefer Kumandas
    • Department of Pediatrics, Faculty of Medicine, Division of Pediatric NeurologyErciyes University
  • Ali Yikilmaz
    • Department of Radiology, Faculty of MedicineErciyes University
Original Paper

DOI: 10.1007/s00381-012-1703-2

Cite this article as:
Mavili, E., Coskun, A., Per, H. et al. Childs Nerv Syst (2012) 28: 905. doi:10.1007/s00381-012-1703-2

Abstract

Aim

The aim of this study is to evaluate the correlation between clinical presentation and the extent of cortical involvement in patients with polymicrogyria.

Materials and methods

The magnetic resonance imaging findings of 26 patients were evaluated for the location and distribution of polymicrogyria. Presence of asphyxia at birth and serological tests for TORCH infections, the presence and type (spastic, flaccid) of motor deficits, mental development, microcephaly, and epilepsy were noted.

Results

Nineteen patients had bilateral, whereas seven had unilateral involvement. Patients with unilateral polymicrogyria presented later with milder symptoms. The most encountered symptom in patients with bilateral involvement was mental motor retardation (MMR) (89%) and speech problems (84%). The clinical presentations of patients with asphyxia and positive serological tests for cytomegalovirus (CMV) were worse. All patients with positive serological tests for CMV had bilateral involvement. The perisylvian region was affected in five (71%) patients with unilateral involvement. The most encountered presenting symptom in these patients was epilepsy. Cerebral palsy was seen in three (43%) of the patients, and all of them had left hemiparesis. Microcephaly, MMR, and speech delay were detected in one (14%) of the patients.

Conclusions

Late presenting epilepsy may be a predictor of a unilateral polymicrogyria and is associated with relatively good prognosis. CMV infection and the presence of asphyxia are predictors of worse prognosis.

Keywords

AsphyxiaChildrenCMVMRIPolymicrogyriaPrognosis

Introduction

Polymicrogyria (PMG) is a malformation of cortical development characterized by many small gyri separated by shallow sulci. Magnetic resonance imaging (MRI) has greatly facilitated the recognition of polymicrogyria [13]. Although PMG can affect any portion of one or both hemispheres, the sylvian fissures are the most affected lobes. Mental retardation, seizures, and motor mental disease are the most presenting clinical features [1]. In this study, we aimed to evaluate the correlation between clinical presentation and the extent of cortical involvement.

Materials and methods

Between the years 2000 and 2007, 14 boys and 12 girls—a total of 26 patients who had PMG on MR imaging—were enrolled into the study. The MR studies and clinical records of these patients were examined retrospectively to confirm the presence and determine the location of PMG. The patients’ complaints were noted. The presence of asphyxia at birth and serological tests for TORCH infections were also sought.

The patients’ age was 45, 4 months (1–228 months) at the time of their most recent MRI. After immobilization of the child, routine cranial MR images were obtained. Generally, wrapping into a blanket after feeding was enough for babies under 3 months. Children between 3 months and 5 years received Dormicum (1–2 mg/kg) which was administered by an anesthesiologist. MRI examinations were performed with a 1.5 T superconductive MR equipment (Philips Gyroscan, Best, the Netherlands). Axial and sagittal T1-W spin echo (TR, 100; TE, 600 ), axial T2-W spin echo (TR, 100; TE, 2,000 ), coronal FLAIR (TR, 100; TE, 4,500), and thin section inversion recovery images were obtained.

MR images were interpreted by two radiologists who were unaware of the clinical findings. Inconsistencies in the findings by the two readers were resolved by discussion. The diagnosis of polymicrogyria was confirmed if regions of the cortex were showing an abnormal gyral pattern, increased cortical thickness, and irregularity of the cortical–white matter junction (Figs. 1, 2). We analyzed the images of polymicrogyria for their distribution.
https://static-content.springer.com/image/art%3A10.1007%2Fs00381-012-1703-2/MediaObjects/381_2012_1703_Fig1_HTML.gif
Fig. 1

Axial T2 MRI shows right perisylvian cortical thickening and pleated gray-white matter border the gyruses are small and the silcuses are shallow

https://static-content.springer.com/image/art%3A10.1007%2Fs00381-012-1703-2/MediaObjects/381_2012_1703_Fig2_HTML.gif
Fig. 2

Axial T2 MRI shows bilateral posterior frontal cortical thickening, the surface of the cerebral cortex is irregular, and the border between the gray matter and white matter is pleated

The presence and type (spastic, flaccid) of motor deficits were noted. According to the affected part of the body, the motor deficits were classified as tetraparesis, hemiparesis, diparesis, and hypotonia. Mental development was evaluated with the Denver 2 test.

Results

The MR and clinical findings of all the patients are summarized in Table 1. The involvement was bilateral in 19 (73%) patients and unilateral in seven (37%) patients. The most frequent presenting symptom was mental–motor retardation (MMR) which was seen in 18 (69%) patients. Other presenting symptoms were seizure, cerebral palsy (CP), and speech or problems or a combination of these.
Table 1

The age and clinical findings of the patient and the localization of the lesions

Age (M)

Localization

Epilepsy

CP

MMR

Microcephaly

Speech problem

Hypoxia

CMV

8

Bilateral frontal

+

+

+

17

Bilateral frontal

+

+

+

4

Bilateral frontal

+

+

+

1

Bilateral occipital

+

TP

+

+

+

+

24

Bilateral temporoparietal

+

DP

+

+

+

9

Bilateral frontotemporal

HT

+

+

+

48

Bilateral frontotemporal

+

LHP

+

156

Bilateral frontotemporal

+

5

Bilateral frontoparietal

+

RHP

+

+

+

+

42

Bilateral parietal perirolandik

LHP

+

+

18

Bilateral perisylvian

TP

+

+

+

10

Bilateral perisylvian

DP

+

+

+

48

Bilateral frontotemporoparietal

+

+

+

12

Bilateral frontoparietooccipital

TP

+

+

+

+

18

Diffuse

+

+

+

+

6

Diffuse

TP

+

+

36

Diffuse

LHP

+

+

+

6

Diffuse

+

+

+

+

4

Diffuse

+

+

+

+

216

Perisylvian

+

228

Perisylvian

+

12

Perisylvian

+

LHP

168

Perisylvian

+

4

Perisylvian

+

56

Frontotemporoparietal

LHP

14

Frontoparietal

+

LHP

+

+

+

+

DP diparesis, HP hemiparesis, LHP left hemiparesis, M month, RHP right hemiparasis, TP tetraparesis

Lesion distribution and clinical findings

Bilateral polymicrogyria was seen in 19 (73%) patients. The bilateral cases were grossly symmetric in 15 patients (78%) and asymmetric in four (22%). The mean admission age to a hospital was 24, 9 months (1–156 months). Asphyxia at birth was present in two (10%) patients. The clinical presentation of the patients with asphyxia was worse than other patients. Serological tests for cytomegalovirus (CMV) infection were positive in six (31%) patients. All patients with positive serological tests for CMV had bilateral involvement.

The most encountered clinical finding in patients with bilateral involvement was MMR seen in 17 (89%) and speech problems seen in 16 (84%) patients—cerebral palsy was seen in 11 (57%) patients. Of the 11 patients with CP, four (36%) had tetraparesis, three (27%) had left hemiparesis, two (18%) had diparesis, one (9%) had right hemiparesis, and one (9%) had hypotonia. Epilepsy and microcephaly was present in ten (53%) patients each.

Diffuse involvement was encountered in five patients. Speech problems, MMR, and microcephaly were the most seen problems each in four of the five patients. Epilepsy and CP were seen in two patients. Two patients had positive serological tests for CMV.

Bifrontal polimycrogyria was detected in three patients. All patients presented with epilepsy, MMR, and microcephaly. CP was not seen in any of the patients. Frontotemporal PMG was detected in three patients. MMR, epilepsy, and CP emerged in two patients each. Speech problems appeared in only one patient. Microcephaly was not seen in these patients.

A bilateral perisylvian PMG was detected in two patients. Cerebral palsy, speech delay, and MMR were present in both patients. Microcephaly was detected in one patient. Epilepsy was not seen in these patients. Bilateral temporoparietal, bilateral frontoparietooccipital, bilateral frontotemporoparietal, bilateral parietal perirolandik, bilateral frontoparietal, and bilateral occipital involvement were detected in one patient each.

Bilateral occipital involvement was the earliest presenting patient. This patient had accompanying asphyxia at birth.

Unilateral involvement was seen in seven (37%) patients. The mean presentation age was 99, 7 months (4–228 months). Epilepsy was present in six (85%) patients. Cerebral palsy was seen in three (42%) patients, and all of them had left hemiparesis. Microcephaly, speech delay, and MMR were detected in only one (14%) patient who had polymicrogyria and associated asphyxia. None of the patients had positive serological tests for CMV.

The perisylvian region was the most affected region seen in five (71%) patients. All the patients presented with epilepsy. Cerebral palsy was seen in one patient. Speech delay, MMR, and microcephaly were not seen in these patients. One patient had unilateral frontoparietotemporal involvement. This patient had only hemiparesis. The last patient with frontoparietal involvement had asphyxia history. Epilepsy, CP, MMR, microcephaly, and speech delay emerged in this patient.

Discussion

Neurons, which will form the cortex originates within the germinal matrix and migrates outwardly. The neurons migrate along radial glial fibers to their final destination. Migration begins at approximately 7 weeks of gestation and is completed between 24 and 40 weeks of gestation [4, 5]. Inhibition of neuronal migration or organization can result in a dysplastic cortex. The development of polymicrogyria has mainly attributed to environmental factors such as hypoxia, intrauterine vascular insults, intrauterine infection, maternal drug abuse, and maternal alcoholism during intrauterine life [1, 68]. Depending on the time of the insult, two types—unlayered and four-layered polymicrogyria—can be distinguished. Layered polymicrogyria results from a cortical injury before the termination of cell migration, whereas unlayered polymicrogyria results from postmigratory insults [3, 4].

The preferred imaging modality for cortical dysplasias is MR imaging, but it may be difficult to differentiate pachygyria and polymicrogyria with MR imaging. Raybaud et al. [9] reported that several differential MR imaging features may help differentiate the two conditions. These features are: (1) the surface of the cerebral cortex which is smooth in pachygyria and irregular in polymicrogyria, (2) the border between the gray matter and white matter which is smooth in pachygyria and pleated in polymicrogyria, (3) the cortical thickness which is variable in polymicrogyria and abnormally thick (two to four times thicker than normal) in pachygyria. The imaging futures of the presented cases fitted those described for polymicrogyria, but we must stress that only histopathological examination is definite.

Polymicrogyria can be generalized or focal, unilateral or bilateral [1, 9, 10]. Hayashi et al. [10] reported that PMG was unilateral in 30 (42%) patients, bilateral in 41 (58%) patients. Also in our study, bilateral polimycrogyria was predominant.

Immature brain is not yet hardwired therefore neonates suffering substantial cortical infarctions often have minimal neurological deficits [2, 3]. In PMG, the extend of cortical involvement affects the symptom complexes and the clinical course. The patients with more limited involvement have a better clinical course [2]. Symptom complexes are similar among patients with comparable involvement. In concordance with this in our study, the symptoms and prognosis was better in unilateral involvement.

The clinical features of the patients with unilateral cerebral polymicrogyria include seizure disorders, spastic hemiparesis, and mental retardation. Seizure disorders are frequent, but spastic hemiparesis and mental retardation are not always present [3] Guerrini et al. [11] reported seven patients with unilateral cerebral focal gyral anomalies. All patients had epilepsy, and four patients suffered from hemiparesis. On the other hand, Pascual-Castroviejo et al. [1] claimed that hemiplegia was the most common symptom in patients with unilateral PMG. In this study, six (85%) patients with unilateral polymicrogyria had seizures, left hemiparesis was seen in three (42%) patients as a presenting symptom. Only one patient with unilateral polymicrogyria had MMR and microcephaly.

The symptom complexes in patients with bilateral involvement depend on the affected site and extent of the disease. Most of the patients with bilateral perisylvian polymicrogyria have mental retardation and epilepsy and present with speech delay or dysfunction [2, 12]. In our study, both patients with bilateral perisylvian polymicrogyria had cerebral palsy, MMR, and speech problems.

It is reported that the patients with bifrontal polymicrogyria present with spastic quadriparesis, delayed motor and language milestones, and mild mental retardation [2]. Voluntary facial motility, slight dysarthria, and resistant epilepsy may also be seen [6, 13]. Barkovich et al. [2] reported that seizures were not seen in bifrontal polymicrogyria, but in our study, all patients with only bifrontal involvement presented with seizures. Patients with parietal polymicrogyria present with medically refractory epilepsy, motor signs, and symptoms are minimal or absent [2, 6]. In this study, cerebral palsy was encountered in six of the seven patients in whom the parietal lobe was involved. Seizures were seen in three patients.

Polymicrogyria seems to be highly epileptogenic. Barkovich and Kjos [14] reported that 26 (72%) of 36 patients with different localization and extension of polymicrogyria had seizures. The entire area of polymicrogyria may not be epileptogenic. The epileptogenic zone lies always adjacent to the malformation and sometimes includes the dyslaminated cortex itself [15]. The epileptic syndrome and also the extent of cortical malformation affect the developmental outcome. Diffuse or bilateral PMG and unilateral localized PMG associated with other lesions have a less favorable clinical course, whereas unilateral localized PMG has a relatively favorable clinical course and prognosis. The incidence of neurological signs is lower in the PMG patients with late-onset epilepsy. Mental retardation is moderate or absent, thus allowing a fairly normal lifestyle [16]. In our cases with unilateral polymicrogyria, epilepsy was the most encountered (six out of seven) and sometimes the only presenting symptom. When epilepsy was the only presenting symptom than the patients presented late which was associated with relatively lower neurological signs and moderate or absent mental retardation.

To summarize our study group, the patients with bilateral or diffuse involvement prone to present earlier with worse symptoms. Epilepsy is the most encountered symptom in unilateral PMG, whereas cerebral palsy and speech delay is prominent in bilateral involvement. Microcephaly and MMR are not seen in patients with unilateral PMG.

Copyright information

© Springer-Verlag 2012