The effectiveness of papilledema as an indicator of raised intracranial pressure in children with craniosynostosis

Clinical findings precede objective diagnostic testing in the identification of increased ICP in syndromic craniosynostosis

Crouzon syndrome is an autosomal dominant disorder resulting in facial dysmorphism and craniosynostosis involving multiple cranial sutures. A common but often unrecognized early complication associated with craniosynostosis is a finding of increased intracranial pressure (ICP). This increase in ICP can lead to optic atrophy, neuronal damage, and mental deficits. The case of a 21-month-old girl with Crouzon syndrome is described. Although the child was clinically asymptomatic, a routine ophthalmic exam revealed papilledema and subsequently increased intracranial pressure and craniosynostosis were found. Cranial expansion and bicanthal advancement were performed to relieve the increased pressure. In cases such as these, long-term follow-up is essential because of the progressive nature of the disorder as well as the possibility of a recurrence of elevated intracranial pressure and a need for secondary decompressive surgery.

Cranial base changes following coronal suturectomy in craniosynostotic rabbits

It has been suggested that surgical release of synostosed sutures may ameliorate various cranial base abnormalities in craniosynostotic patients. The present study was designed to test this hypothesis in a rabbit model with familial coronal suture synostosis (CSS). Data were collected from 56 New Zealand White rabbits: 32 unaffected controls, 11 with unoperated CSS, and 13 with CSS released by suturectomy performed at 25 days of age. Serial radiographs were taken at 25, 42 and 84 days. Linear, angular and triangular shape cranial base measurements were compared using ANOVA and tensor biometric analysis. Results revealed that at 84 days, both groups of CSS rabbits had significantly (p < 0.05) different anterior and total cranial base lengths, flatter cranial base angles, and dysmorphic anterior cranial base shapes when compared with normals. Significant (p < 0.05) differences were noted only for palatal and cranial base angles and posterior cranial base shape between CSS rabbits with and without suturectomy. However, significant (p < 0.05) changes were noted between pre- and postoperative measurements in posterior and total cranial base lengths and anterior and posterior cranial base shapes in CSS rabbits with suturectomy. Results revealed that surgical release of synostosed coronal sutures through suturectomy did not normalize cranial base growth patterns in CSS rabbits. These findings may be explained by the relatively late age of surgical release or suturectomy site resynostosis with continued dysmorphic cranial base growth. Alternatively, cranial base abnormalities seen in CSS rabbits may be early primary malformations, not secondary deformations amenable to surgical modification.

Coronal suturectomy does not cause acute postoperative displacement in the cranial bases of craniosynostotic rabbits

Approximately 300 to 500 infants per 1,000,000 have prematurely fused cranial sutures (craniosynostosis). Craniosynostosis can result in increased intracranial pressure and craniofacial deformities, which often require extensive and costly craniofacial surgery. Because the neurocranium and basicranium are developmentally interrelated, understanding their influence on one another is important for surgical planning. Although surgery has been found to have long-term effects on the cranial bases of craniosynostotic human beings and rabbits, the biological mechanisms behind these effects remain uncertain. Some researchers have suggested that the surgical release of synostosed sutures alters long-term growth patterns, resulting in cranial base differences between craniosynostotic individuals who undergo surgery and those who do not. Additionally, some investigators have proposed that an acute and surgically related displacement of basicranial elements may contribute to the observed differences. The current study examines acute postoperative changes in four lengths, three angles, and three triangles between cranial base landmarks in a sample of seven New Zealand white rabbits with familial nonsyndromic craniosynostosis. Results indicate that suturectomy caused no statistically significant (P < 0.05) acute length, angular, or shape differences in the cranial base. Thus, previous long-term cranial base differences found between rabbits that were operated on and those that were not were probably not caused by an acute displacement of skeletal elements as a result of surgery. These findings suggest that postoperative cranial base changes may be related more to chronically altered growth patterns than to acutely altered changes in intracranial pressure or dural tension.

Perioperative transcranial Doppler US to evaluate intracranial compliance in young children undergoing craniosynostosis repair surgery

PURPOSE

To determine whether measurements with transcranial Doppler ultrasonography (US) of resistive indexes (RIs) of basal cerebral arteries with pressure provocation can be used to identify infants and children with craniosynostosis who have abnormal intracranial compliance and to study the effects of surgery on compliance.

MATERIALS AND METHODS

Transcranial Doppler US was performed through the temporal squama, fontanels, and existing skull defects prior to and immediately following cranioplasty. Twenty-four studies were performed in six patients with multisuture synostosis, and 61 studies were performed in 26 patients with single-suture synostosis. Study findings were compared with those of 23 control subjects and were characterized as normal or abnormal on the basis of age-specific normal criteria for RI.

RESULTS

In multisuture synostosis, results of six of the nine preoperative transcranial Doppler US studies were abnormal. During postoperative follow-up, three recurrences requiring reoperation occurred, one of which was detected with abnormal transcranial Doppler US findings. In single-suture synostosis, results of seven of the 26 preoperative transcranial Doppler US studies were abnormal, and all occurred in young infants with sagittal and unicoronal synostosis. Immediate effects of surgery were variable. All patients with sagittal synostosis had a significant immediate postoperative increase in RI, which normalized during postoperative follow-up. There was no significant difference in RI between patients with successfully treated craniosynostosis and control subjects.

CONCLUSION

Transcranial Doppler US can be used to identify patients with craniosynostosis with decreased intracranial compliance, and it is a suitable noninvasive test to monitor the effects of surgery on compliance.

The craniofacial dysostosis syndromes: current surgical thinking and future directions

Craniofacial dysostosis is the term applied to familial forms of craniosynostosis in which the sutural involvement generally includes the cranial vault, cranial base, and midfacial skeletal structures. The syndromic forms of craniofacial dysostosis were initially described by Carpenter, Apert, Crouzon, Saethre and Chotzen, Pfeiffer, and others. In addition to the dysmorphic cranial features, affected individuals may have profound alterations in facial skeletal development. Surgical reconstruction requires thoughtfully sequenced and staged procedures with consideration for the individual's specific malformations, craniofacial growth patterns, and psychosocial needs. Management of the craniofacial dysostosis syndromes is surgical, but the indications and the timing, type, and effectiveness of each stage of reconstruction have not been well evaluated and remains as much an art as a science. This article reviews the specific characteristic clinical features of the craniofacial dysostosis syndromes and presents current philosophy and rationale for the staging of reconstruction.

The Craniofacial Dysostosis Syndromes: Current Surgical Thinking and Future Directions

Craniofacial dysostosis is the term applied to familial forms of craniosynostosis in which the sutural involvement generally includes the cranial vault, cranial base, and midfacial skeletal structures. The syndromic forms of craniofacial dysostosis (CFD) were initially described by Carpenter, Apert, Crouzon, Saethre and Chotzen, Pfeiffer, and others. In addition to the dysmorphic cranial features, affected individuals may have profound alterations in facial skeletal development. Surgical reconstruction requires thoughtfully sequenced and staged procedures with consideration for the individual's specific malformations, craniofacial growth patterns, and psychosocial needs.

Management of the CFD syndromes is surgical, but the indications and the timing, type, and effectiveness of each stage of reconstruction have not been well evaluated and remains as much an art as a science. This article reviews the specific characteristic clinical features of the CFD syndromes and presents current philosophy and rationale for the staging of reconstruction.

Age-related changes in intracranial pressure in rabbits with uncorrected familial coronal suture synostosis

OBJECTIVE

Chronic, elevated intracranial pressure (ICP) in craniosynostotic infants may result in ocular and neurocapsular problems; however, not all infants exhibit elevated ICP. Clinical ICP studies are further confounded by small and heterogeneic samples, multiple-suture involvement, and varying surgical management protocols. The present study was designed to describe longitudinal changes in ICP in a large, homogenous sample of rabbits with uncorrected familial, nonsyndromic coronal suture synostosis.

METHODS

Ninety-one rabbits were divided into four groups: (1) normal rabbits (n = 28), (2) rabbits with delayed-onset coronal suture synostosis (DOCS; n = 25), (3) rabbits with unilateral coronal suture synostosis (UCS; n = 12), and (4) rabbits with bilateral coronal suture synostosis (BCS; n = 26). ICP was measured at 24 and 42 days of age using a Codman epidural microtransducer.

RESULTS

Rabbits with BCS had a significantly (p < .05) higher mean ICP at 25 days of age than rabbits in the other three groups by approximately 146%. However, by 42 days of age, mean ICP in normal control rabbits and rabbits with DOCS was significantly (p < .01) increased compared with their mean ICP values seen at 25 days of age, while mean ICP in BCS rabbits significantly (p < .01) decreased (by 32%) over the same time period. ICP in rabbits with UCS was between that seen in normal control rabbits and rabbits with BCS and did not significantly (p > .05) change over time.

CONCLUSIONS

These findings suggest that the degree of suture involvement may be related to early increases in ICP. Possible multifactorial explanations for intracranial decompression and compensation in the craniosynostotic rabbit model are discussed.

Brain growth rates in craniosynostotic rabbits

OBJECTIVE

It has been suggested that abnormal brain morphology or growth rates may be a primary causal factor of craniosynostosis due, in part, to a lack of normal growth stretch and tension at the sutural margins. The purpose of the present study was to quantify cerebral hemisphere morphology and growth in a rabbit model of nonsyndromic coronal suture synostosis to determine whether cerebral dysmorphology is primary or secondary to synostosis in this model.

DESIGN

Fifty-seven brains (114 hemispheres) were examined from 40 normal control rabbits and 17 rabbits with bilateral coronal suture synostosis ranging in age from 25 to 450 days postconception (synostosis occurs at approximately 23 days postconception in this model). The calvariae were removed, the brains were fixed in 10% paraformaldehyde, and in situ bilateral measurements of cerebral hemisphere length and cerebral hemisphere width were obtained using a Wild microscope with a camera lucida attachment and digital caliper. Regression analysis was used to compare cerebral cortex growth rates by age between the two groups.

RESULTS

Cerebral hemisphere width and cerebral index regression line slopes had similar y intercepts (23 day postconception) with significantly (p < .05) diverging slopes over time. Normal rabbits increased more rapidly than synostosed rabbits. No significant (p > .05) differences were noted in regression line slopes between groups for cerebral hemisphere length by age or length by width.

CONCLUSIONS

Cerebral dysmorphologies are probably a compensatory, secondary (postsynostotic) event and not a primary causal factor of craniosynostosis in this rabbit model of human familial, nonsyndromic coronal suture synostosis.

The beaten copper cranium: a correlation between intracranial pressure, cranial radiographs, and computed tomographic scans in children with craniosynostosis

OBJECTIVE

The beaten copper appearance of the cranium, as well as other cranial radiographic and computed tomographic findings in children with craniosynostosis, is often interpreted by clinicians as evidence of elevated intracranial pressure (ICP). However, a correlation between radiological findings and ICP measurements has not been previously demonstrated, and their usefulness in detecting elevated ICP has not been defined.

METHODS

To address those issues, 123 children with craniosynostosis who had cranial radiographs and ICP monitoring were studied. To assess the specificity of certain radiological findings to patients with craniosynostosis, cranial radiographs of patients with craniosynostosis were compared to those of age- and sex-matched controls. In patients with craniosynostosis, findings on cranial radiographs were compared to computed tomographic scans of the brain. Radiographic findings were then correlated with ICP measurements obtained while the patient was sleeping, which was measured using a Camino fiberoptic ICP monitor (Camino Laboratories, San Diego, CA). All radiographs were independently analyzed by two radiologists who were blinded to clinical and ICP data.

RESULTS

A diffuse beaten copper pattern, erosion of the dorsum sellar, and suture diastasis were seen more commonly in patients with craniosynostosis than in controls (P < 0.05), but the presence of the beaten copper pattern was no more common in children with craniosynostosis. ICP was greater when a diffuse beaten copper pattern, dorsum sellar erosion, suture diastasis, or narrowing of basal cisterns was present (P < 0.05).

CONCLUSION

Although this study demonstrates that some cranial radiographic and computed tomographic findings do correlate with elevated ICP, the sensitivity of radiological methods for detecting elevated ICP is universally low and they are not recommended to screen for elevated ICP in children with craniosynostosis.