Severe holocord syrinx in a child with megalencephaly-capillary malformation syndrome

Surgical management of Chiari malformation type 1 associated to MCAP syndrome and study of cerebellar and adjacent tissues for PIK3CA mosaicism

BACKGROUND

Subjects with Megalencephaly-Capillary Malformation-Polymicrogyria syndrome (MCAP) can present with a Chiari Malformation Type 1 and resulting alterations in cerebrospinal fluid (CSF) dynamics, which may require surgical treatment. The aim of this paper is to describe the features of children with MCAP who underwent surgical decompression for CM1, and to explore the PIK3CA variant allele frequency (VAF) identified in cerebellar parenchyma and other adjacent structures.

METHODS

This study reviewed two cases of children with CM1 and MCAP who underwent surgical decompression treatment. These two cases were part of a national cohort of 12 MCAP patients who had CM1, due to their surgical eligibility. Tissue samples were obtained from the cerebellar tonsils and adjacent anatomical structures during the surgical procedures. Samples were then subsequently analyzed for PIK3CA postzygotic variants.

RESULTS

In both cases, alterations in CSF dynamics, specifically hydrocephalus and syringomyelia, were observed and required surgical treatment. PIK3CA targeted sequencing determined the VAF of the postzygotic variant in both cerebellar and adjacent bone/connective tissues.

DISCUSSION

The recognition of a CM1 comorbidity in MCAP patients is of paramount importance when considering personalized treatment options, especially because these patients are at higher risk of developing complications during surgical decompression surgery. The variable PIK3CA VAF identified in the different analyzed tissues might help explain the heterogeneous nature and severity of anomalies observed in the volume of the posterior fossa structures in MCAP patients and associated CSF and venous disorders.

A standard of care for individuals with PIK3CA-related disorders: An international expert consensus statement

Growth promoting variants in PIK3CA cause a spectrum of developmental disorders, depending on the developmental timing of the mutation and tissues involved. These phenotypically heterogeneous entities have been grouped as PIK3CA-Related Overgrowth Spectrum disorders (PROS). Deep sequencing technologies have facilitated detection of low-level mosaic, often necessitating testing of tissues other than blood. Since clinical management practices vary considerably among healthcare professionals and services across different countries, a consensus on management guidelines is needed. Clinical heterogeneity within this spectrum leads to challenges in establishing management recommendations, which must be based on patient-specific considerations. Moreover, as most of these conditions are rare, affected families may lack access to the medical expertise that is needed to help address the multi-system and often complex medical issues seen with PROS. In March 2019, macrocephaly-capillary malformation (M-CM) patient organizations hosted an expert meeting in Manchester, United Kingdom, to help address these challenges with regards to M-CM syndrome. We have expanded the scope of this project to cover PROS and developed this consensus statement on the preferred approach for managing affected individuals based on our current knowledge.

Megalencephaly-capillary malformation syndrome and associated hydrocephalus: treatment options and revision of the literature

PURPOSE

We describe our series of 4 patients with megalencephaly-capillary malformation syndrome (MCAP) and review the literature in order to assess the optimal treatment for the associated hydrocephalus.

METHODS

We review our institutional series of hydrocephalus associated with MCAP and review the literature, analyzing the causes that could originate the hydrocephalus and the different types of treatments proposed for them.

RESULTS

Of our patients treated with ventriculoperitoneal (VP) shunt, one suffered a surgical revision of the shunt and died due to a cranial trauma unrelated to her syndrome or the previous shunt surgery, and the other did not undergo surgical revisions until the end of her follow-up. Our patients treated with endoscopic third ventriculostomy (ETV) have improved their symptomatology and have not suffered of any complications related to the hydrocephalus after the ETV surgery.

CONCLUSIONS

We update the treatment of MCAP-associated hydrocephalus and propose ETV as a valid treatment, as it seems a safe procedure with a low rate of complications.