High-frequency ultrasound confirmation of positional plagiocephaly.

OBJECT: Positional plagiocephaly has become an increasing problem for pediatricians and craniofacial specialists. Diagnosis is commonly based on history and clinical features, but may be difficult in some cases when characteristic features are missing and radiographic studies seem to be necessary. Near-field high-frequency ultrasound has been used to evaluate the sonographic findings of suture anatomy and confirm the diagnosis of positional plagiocephaly as well as provide information of prognostic value. METHODS: The authors report on 100 pediatric patients between the ages of 2 and 13 months, who were admitted to their department since 2004 with an abnormal head shape suggesting nonsynostotic plagiocephaly (NSP). Suture anatomy was examined using a 7.5-MHz linear transducer and a Siemens Elegra ultrasound scanner by two independent investigators. Measurements of suture width and bone thickness were obtained, and the findings were correlated with clinical data as well as sonographic and histopathological findings in both normal and fused cranial sutures. Interobserver variability was assessed by means of paired t-tests. Linear regression analyses were used for correlating patient age with suture width and bone thickness. Patency of lambdoid sutures was confirmed in 99 cases in which the clinical findings suggested NSP. Morphological characteristics of the sutures--interosseous hypoechoic areas between hyperechoic bone plates--were comparable to those of normal cranial sutures. In one patient, partial synostosis was diagnosed. Overlapping hyperechoic bone plates were found in 51 patients on the affected side of the skull and in 36 patients on the unaffected side. Suture width decreased over time from 6.5 to 2 mm, and thickness of bone in the affected area increased from 0.6 to 1.2 mm until the age of 13 months. The method was found to be limited by age (upper limit 13 months) and anatomical variations but did not show any interobserver variability (p < 0.05). CONCLUSIONS: High-frequency ultrasound is a relatively inexpensive, safe, and easy-to-use tool for confirming the diagnosis of positional plagiocephaly and excluding true synostosis. Overlapping bone plates may be seen on the affected side of the skull in a majority of plagiocephalic patients, but this finding seems to have no prognostic value regarding early fusion of sutures and therefore should not affect treatment decisions. With its lack of interobserver variability and the advantage of not involving ionizing radiation, sonography has the potential to be a standard modality for investigating plagiocephaly in infants and should be offered in craniofacial outpatient clinics.

Preoperative assessment of motor cortex and pyramidal tracts in central cavernoma employing functional and diffusion-weighted magnetic resonance imaging.

BACKGROUND: Functional MRI (fMRI) combines anatomic with functional information and has therefore been widely used for preoperative planning of patients with mass lesions affecting functionally important brain regions. However, the courses of functionally important fiber tracts are not visualized. We therefore propose to combine fMRI with diffusion-weighted MRI (DWI) that allows visualization of large fiber tracts and to implement this data in a neuronavigation system. METHODS: DWI was successfully performed at a field strength of 1.5 Tesla, employing a spin-echo sequence with gradient sensitivity in six noncollinear directions to visualize the course of the pyramidal tracts, and was combined with echo-planar T2* fMRI during a hand motor task in a patient with central cavernoma. RESULTS: Fusion of both data sets allowed visualization of the displacement of both the primary sensorimotor area (M1) and its large descending fiber tracts. Intraoperatively, these data were used to aid in neuronavigation. Confirmation was obtained by intraoperative electrical stimulation. Postoperative MRI revealed an undisrupted pyramidal tract in the neurologically intact patient. CONCLUSION: The combination of fMRI with DWI allows for assessment of functionally important cortical areas and additional visualization of large fiber tracts. Information about the orientation of fiber tracts in normal appearing white matter in patients with tumors within the cortical motor system cannot be obtained by other functional or conventional imaging methods and is vital for reducing operative morbidity as the information about functional cortex. This technique might, therefore, have the prospect of guiding neurosurgical interventions, especially when linked to a neuronavigation system.

Intraoperative three-dimensional visualization of the pyramidal tract in a neuronavigation system (PTV) reliably predicts true position of principal motor pathways.

BACKGROUND: This prospective study employs anisotropic diffusion-weighted (ADW) magnetic resonance imaging for the integration of individual spatial information concerning the principal motor pathways into the operating room during microneurosurgery in the central region. We hypothesize that the three-dimensional (3-D) visualization of the pyramidal tract position (PTV) in a neuronavigation system based on ADW provides valid information concerning the position and extension of the principal motor pathways. METHODS: A total of 13 consecutive patients with lesions adjacent to the pyramidal tracts and the central region underwent microneurosurgery with the help of pyramidal tract visualization (PTV). An ADW sequence obtained preoperatively was fused to an anatomic navigation sequence. The 3-D reconstructions of the precentral gyrus (PG), the pyramidal tract, and the tumor were available in a customized neuronavigation system during surgery. Intraoperatively the PG was identified on the basis of the aforementioned data. Electric motorcortex stimulation (CS) was used to directly verify the PG location and indirectly the fiber tract position. RESULTS: In 11 cases (92%) the prediction of the principal motor pathways' position was correct. In one case of a meningioma, according to PTV, the tumor was falsely localized postcentrally. In the case of a precentral cavernoma, no motor response could be elicited by cortical stimulation. CONCLUSION: Intraoperative PTV on the basis of ADW provides the neurosurgeon with reliable information concerning the position of the principal motor pathways during intracranial procedures as proved with intraoperative electrophysiological testing. The technique has the potential to reduce operative morbidity. PTV is straightforward and can be adapted to other customized neuronavigation devices.

Ultrasound in the diagnosis of craniosynostosis.

Diagnosis of craniosynostosis is based on clinical aspects but may be difficult in some cases where characteristic features are missing and radiographic imaging is necessary. In this context near-field high-frequency ultrasound has been used to evaluate the sonographic characteristics of synostotic sutures and its potential confirming the correct diagnosis. Sutures of 26 infants, aged 2-7 months, were investigated by ultrasound (Siemens Elegra, 7.5 MHz linear scanner). Sonographic features of synostotic sutures were correlated to CT imaging and compared to the sonographic and histopathological findings of normal cranial sutures. Hyperechogenic bridging of sutures with or without ridging were the characteristic aspects of synostotic sutures. All 26 patients could be reliable diagnosed showing partial (n = 21) or total fusion (n = 5) of one or more sutures consisting with craniosynostosis. Length of synostosis was identified exactly by sonography and imaging found to enable a classification of ultrastructural details of bony and soft tissue next to the synostotic suture. Ultrasound is a less expensive, nonradiating and easy-to-handle tool ensuring the diagnosis of craniosynostosis. Sonography offers the potential to be a standard investigation for infants with head deformities suspecting a suture pathology and has been therefore integrated in our craniofacial outpatient clinic as a daily routine method.