Posterior calvarial distraction for complex craniosynostosis and cerebellar tonsillar herniation

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Children with syndromic, multisuture, and lambdoid craniosynostosis undergoing calvarial surgery often have Chiari malformation type I (CM-I) (or cerebellar tonsillar herniation). The optimal management of this patient group, including the surgical techniques and timing of surgery, remains uncertain. Posterior calvarial distraction (PCD) is an effective method to increase the supratentorial cranial volume and improve raised intracranial pressure in children with complex craniosynostosis. This study investigated the efficacy of PCD in posterior fossa (PF) volume expansion and treatment of CM-I and associated syringomyelia (syrinx) in this group of children.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>This retrospective study included patients who were surgically treated between 2006 and 2015. Over 10 years, 16 patients with multisuture synostosis, lambdoid synostosis, or craniosynostosis associated with a confirmed genetic syndrome, and a concurrent CM-I, were included. The mean age at the time of surgery was 5.1 years (range 8 months–18 years). Fourteen patients had pansynostosis and 2 had lambdoid synostosis. Eight had a confirmed syndromic diagnosis (Crouzon in 8, Apert in 4, Pfeiffer in 1, and Saethre-Chotzen in 1). Ten patients had raised intracranial pressure; 4 had syringomyelia.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>The average clinical follow-up was 50 months (range 9–116 months). Clinically, 9 patients improved, 7 remained stable, and none deteriorated. The average distraction distance was 23 mm (range 16–28 mm). The PF anterior-posterior (AP) distance/width ratio increased from 0.73 to 0.80 mm (p = 0.0004). Although an osteotomy extending inferior to the torcula (compared with superior) was associated with a larger absolute PF AP distance increase (13 vs 6 mm, p = 0.028), such a difference was not demonstrable when the PF AP distance/width ratio was calculated. Overall, the mean tonsillar herniation improved from 9.3 to 6.0 mm (p = 0.011). Syrinx dimensions also improved in the AP (from 7.9 to 3.1 mm) and superior-inferior (from 203 to 136 mm) dimensions. No patients required further foramen magnum decompression for CM. Of the 16 patients, 2 had subsequent frontoorbital advancement and remodeling, of which 1 was for volume expansion and 1 was for cosmetic purposes. Two patients required CSF shunt insertion after PCD.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>Following PCD, PF volume increased as well as supratentorial volume. This morphometric change was observed in osteotomies both inferior and superior to the torcula. The PF volume increase resulted in improvement of cerebellar tonsillar herniation and syrinx. PCD is an efficacious first-line, single-stage treatment for concurrent pansynostosis and lambdoid craniosynostosis, CM-I, and syrinx.</jats:p></jats:sec>

Extended experience in parieto-occipital expansion surgery by meander technique—clinical and radiological evaluation

“…distractive methods, as demonstrated by a review by Greives et al (22.6%) [30]. The technique of osteogenic distraction appears to be associated with higher rates of infection (7.4-29%) [1,17,22,25,28,31,32], failure of the implants used for the fixation with loosening or dislocation of its components (0-12%) [1,32,33], and dural tears (6.5-10%) [30][31][32]. A possible advantage of the distraction technique is the shorter surgery time and a limited blood loss with consecutive lower transfusion rate [17].…”

“…However, secondary Chiari conditions might not necessarily respond to a posterior cranial vault decompression [24,25]. For that reason, a suboccipital foramen magnum decompression together with the parieto-occipital remodeling was also discussed [26][27][28].…”

Multisuture and Syndromic Craniosynostoses

“…[ 33 34 35 ] PCVD is the standard initial step in most described algorithms when raised ICP is the presentation. [ 36 37 ] Most units use PCVD to postpone FOAR to a later date. [ 38 ] ICP being the earliest issue in SCs,[ 23 39 40 41 42 43 44 ] PCVD is a constant option.…”

“…The decision for surgery on asymptomatic patients was based on the current knowledge of the condition’s natural history. [ 37 ] Our protocol only differed in older children (arbitrarily over 2 years) unless Chiari malformation is a presenting feature.…”

Supratentorial vs infratentorial posterior calvarial distraction osteogenesis for the increase of ICV in children with syndromic or multi-suture craniosynostosis: a retrospective cohort study

“…Aesthetically, limited expansion at specific calvarial sutures results in asymmetrical skull growth and abnormal head shape [ 6 ]. Posterior calvarial distraction (PCD) may be used to normalize ICP and rectify head shape with controlled calvarial expansion [ 7 ]. This can be performed supratentorially or infratentorially, the distinction being the position of the inferior osteotomy relative to the torcular shelf and subsequently the tentorium cerebelli [ 8 ].…”