Congenital bilateral perislyvian syndrome: A rare case report

Abstract

Congenital bilateral perisylvian syndrome, also known as bilateral periopercular syndrome or perisylvian polymicrogyria, is an exceptionally rare neurological disorder characterized by homogeneous clinicoradiological symptoms. There are consequently wide spectrums of clinical manifestations. In perisylvian syndrome. MRI is the preferred imaging technique. We describe the case of a female 8-year-old child who has a history of generalized tonic-clonic seizures. and was identified to have bilateral perisylvian syndrome based on MR imaging findings.

Introduction

Congenital Bilateral Perisylvian Syndrome (CBPS) is synonymous with perisylvian syndrome, perisylvian polymicrogyria, worster drought syndrome, and bilateral opercular syndrome [1].

Polymicrogyria is a cortical development abnormality defined by aberrant arrangement and excessive folding of cerebral cortical cell layers, frequently with the fusion of the gyral surfaces, which can be isolated, regional, or cover the entire cortical mantle [2].

Case report

We present the case of an 8-year-old female child with a history of generalized tonic-clonic seizures. The child had a mental disability, phonation problems, and developmental delays.

There is no family history of symptoms similar to this. The baby was delivered via standard vaginal delivery.

On examinations, the patient's overall health and vital signs were good. Dysarthria and limited tongue mobility were detected during the clinical evaluation. The electroencephalogram was abnormal.

We received the patient after a brain CT scan performed outside our structure found no abnormalities, and a cerebral MRI was recommended due to the patient's neurological problems.

The cerebral MRI reveals a bilateral enlargement of the Sylvian fissures with an irregular cortex and a thickening of the gray matter surrounding them. (Figs. 1, and 2).

Fig. 1.

Axial section of a T2 FLAIR = MRI (A) and a coronal section of a T2 MRI (B). Showing perisylvian cortical thickness on both sides, asymmetrically (red star) with enlargement of the Sylvian fissure (blue arrow), more pronounced on the right side. The insula is exposed with a thick and smooth long insular lobe.

Fig. 2.

The sagittal section of a T1 sequence MRI showing, shows perisylvian cortical thickness on both sides, asymmetrically (red star) with enlargement of the Sylvian fissure (blue arrow), the insula is exposed with a thick and smooth long insular lobe.

CBPS was diagnosed based on clinical and imaging data. We tried treating the patient with phenobarbital monotherapy, however, there was no improvement, so we changed to phenytoin, which greatly reduced the patient's epileptic seizures. We also managed the patient with specialized care in a psychomotor rehabilitation center to treat speech disorders and dysarthria.

Discussion

The term “polymicrogyria” describes the aberrant appearance of the cortex with many abnormally small convolutions and an insufficient number of sulci. Essentially, it is an organizational aberration in which neurons travel to the cortex where they are meant to be but are disseminated incorrectly [1].

The CBPS development mode is unknown. The insult's postulation begins before the 30th week of pregnancy when the opercula frequently predominate the insula [3].

CBPS is a neurological disorder that interferes with a development that is defined by homogeneous clinic radiological symptoms with polymicrogyria as the underlying defect.

Although the specific origin is unknown, several processes have been proposed, including gene mutation, postmigrational vascular accident, bilateral cerebral hypoperfusion, and potential injury during neuronal migration. Familial, autosomal, and X-linked inheritance has been reported [2].

The CBPS can be acquired or inherited. The family variant of the condition has X-linked, autosomal dominant, and autosomal recessive modes of inheritance [4].

It has been observed in patients with the congenital anomalies/mental retardation syndromes of Aicardi syndrome, Walker-Warburg syndrome, and Prader-Willi syndrome. CBPS was also observed in patients with chromosomal abnormalities, such as 22q11 deletion patients [5].

CBPS have been classified according to their major distribution; the distribution influences clinical presentation [1]. The presence of oropharyngoglossal dysfunction, moderate to severe dysarthria, and bilateral perisylvian abnormalities on MRI are essential characteristics in almost of cases. The other criteria include epilepsy, mental retardation, delayed milestones, and abnormal electroencephalogram, which are observed in over 85% of patients [2]. In addition to developmental language difficulties, CBPS is usually linked to speech disorders and dysarthria [5]. In our situation, the patient had epilepsy, dysarthria, and verbal impairment.

In 43%-93% of people with CBPS, epilepsy develops. The severity and location of the perisylvian anomalies are unrelated [5].

Polymicrogyria may be difficult to demonstrate with CT but is identifiable on MRI as the thickened cortex, poorly developed sulci, and an irregular margin at the cortical white matter junction [1].

In CBPS, MRI is the preferred imaging technique. Imaging results show a perisylvian region with polymicrogyria cortex with focal cortical thickening (Figs. 1 and 2) T2W hyper-intensity in adjacent white matter and loss of gray-white matter distinction [4].

Grading the severity using MRI is also helpful (Grade 1 is the most severe and Grade 4 is the mildest): Grade 1, perisylvian microgyria extending to the frontal or occipital pole; Grade 2, polymicrogyria extending beyond the perisylvian region but not to either pole; Grade 3, polymicrogyria of the perisylvian region alone; and Grade 4, polymicrogyria in the only posterior perisylvian region [3].

Antenatal ultrasonography diagnosis can be difficult since the brain regions affected by this disorder may not have completed their final folding until their birthday [2].

There is no treatment for the bilateral perisylvian syndrome. Antiepileptic drugs are used as the primary form of treatment, and speech therapy is also provided [4].

CBPS is an incurable disease. Patients can benefit from interdisciplinary rehabilitation strategies such as speech therapy, oral motor skill and swallowing education, and tongue muscle exercises. Percutaneous gastrostomy would be helpful if feeding were seriously compromised [3].

The more severe epilepsy, the more challenging it is to treat. Only 50%-60% of people can successfully manage their epilepsy with just medication [5]. which was the case for our patient who progressed well on monotherapy.

Conclusion

CBPS is a rare neurological disorder associated with pseudobulbar palsy, cognitive deficits, and epilepsy and has been linked to bilateral perisylvian cortical dysplasia in neuroimaging investigations.

The preferred imaging technique for CBPS is MRI, early diagnosis and appropriate care must be implemented to prevent a gradual decline in clinical circumstances.

Patient consent

Written informed consent for publication was obtained from patient.