Intracranial lipomas are rare congenital malformations. They are usually pericallosal asymptomatic midline lesions. Other brain malformations are often seen in association with intracranial lipomas. We describe the findings of imaging studies, including computed tomography (CT), magnetic resonance (MR) imaging, and MR angiography, along with a brief review of the literature. The frequency and the spectrum of the associated brain malformations are also discussed. We retrospectively reviewed CT and MR findings of 24 patients (14 female, 10 male, mean age 38.6 years) diagnosed with intracranial lipoma between December 2000 and June 2004 in two different radiology departments. Seventeen of the patients were diagnosed using cranial MR and seven with cranial CT. The CT density of all lesions was measured. Imaging characteristics of lipomas, morphological findings and associated malformations were described. The intracranial locations of the lipomas were left-sided quadrigeminal cistern (n=3), right-sided quadrigeminal cistern (n=4), interpeduncular cistern (n=1), sylvian fissure (n=3), interhemispheric fissure (n=3), choroid plexus (n=2), intercerebellar fissure (n=3), corpus fornicis (n=1) and the periphery of the corpus callosum (n=4). Eighteen of the intracranial lipomas were tubulonodular; six were curvilinear. Associated anomalies were observed in six patients. All of the patients with sylvian fissure lipoma had seizures. The two preferential sites of intracranial lipomas were pericallosal and dorsal mesencephalic. Most intracranial lipomas are found incidentally during neuroradiological investigations. CT and MR examination usually lead to the diagnosis, because of the very low attenuation values of lipomas on CT and the short T1 and T2 on MR. Midline anomalies and other malformations such as aneurysms are frequently associated with intracranial lipomas. Careful radiologic evaluation is therefore necessary to evaluate associated pathologies. Sylvian fissure lipomas should be considered in the differential diagnosis of patients with epilepsy.

Intracranial lipomas: importance of localization.

The discovery of relevant causative genes has subdued the lumping versus splitting debate with respect to a growing number of syndromes. However, it remains paramount to define unknown genesis syndromes as precisely and appropriately as possible in order to provide accurate prognosis and to facilitate future research. The presentation of a 14-month-old girl, of normal intelligence, who had a colobomatous right eye with cyst, minor intracranial MRI variants, and an area of sparse scalp hair containing a 1 by 1.5 cm, soft, domed, and indented skin lesion suggested a diagnosis of mild oculocerebrocutaneous syndrome (OCCS). An initial exploration of the literature exposed the extreme variability in cases that have been reported as OCCS, and emphasized its possible relationship to encephalocraniocutaneous lipomatosis (ECCL), thus challenging the initial diagnosis. Cases reported, or discussed by others, as possible OCCS (40) and ECCL (44) were reviewed as completely as possible in an effort to determine whether diagnostic criteria could be developed for these syndromes, and to see whether or not evidence favored their continued separation as two syndromes. The approach used was to summarize the data for all cases, to select major and minor diagnostic criteria on the basis of the relative specificity and/or frequency of a sign, to then apply the criteria in a standard fashion and to review the outcome to see if the classification of cases made clinical sense, and to make appropriate adjustments. The criteria were not chosen so as to separate the syndromes and in some instances the same criteria could apply to either syndrome. An approach is outlined for handling reports of patients that purport to be variants or to expand the spectrum of a syndrome, and in the case of OCCS and ECCL this resulted in most such examples being excluded. Application of diagnostic criteria suggests that OCCS and ECCL are distinct, and that some case reports, including some purporting to expand the spectrum of OCCS, should be excluded, at least until such time as the etiology of these conditions is known and those cases can be tested. These diagnostic criteria were developed on the basis of literature reports that varied in their quantity and quality of detail. Furthermore, in many cases reliance had to be placed on copies of original studies with resultant degradation of photographic information. Modern ocular imaging, and histopathology of eye and skin malformations, will often clarify the specific nature of a malformation and, therefore, define exact diagnostic criteria and leave fewer uncertain cases. In the absence of anomalies in those systems, or if histopathology or appropriate imaging is unavailable, the diagnosis in some cases will continue to remain uncertain; this is not an argument for lumping the syndromes.

Oculocerebrocutaneous and encephalocraniocutaneous lipomatosis syndromes: blind men and an elephant or separate syndromes?

Encephalocraniocutaneous lipomatosis (ECCL) is a sporadically occurring neurocutaneous disorder characterized by ocular anomalies, skin lesions, and CNS anomalies. We report on four new patients with this syndrome. Additionally, we reviewed (i) the brain imaging studies and clinical data of these new cases of ECCL and six other previously published ECCL patients, and (ii) the literature on 42 other patients who had undergone some form of neuroimaging, including three cases with probable or uncertain ECCL diagnoses. Thirty-three of 52 patients showed intracranial lipomas, frequently of cerebello-pontine location, and/or spinal lipomatosis. The latter has been found in 12/13 patients who had imaging studies of the spine. Other frequent findings included congenital anomalies of the meninges, in particular arachnoid cysts, and remarkably asymmetric anomalies caused by putative focal vascular defects, such as (partial) atrophy of one hemisphere or thin cerebral mantle, porencephalic cysts and calcifications. Vessel anomalies were found in nine patients. No correlation between the brain anomalies and the degree of retardation or epilepsy could be established. These data provide evidence that the brain anomalies in ECCL are not primary brain malformations but arise secondary to a mesenchymal defect affecting mostly neural crest derivatives.

Brain Anomalies in Encephalocraniocutaneous Lipomatosis

Study design A case report of bipartite atlas associated with os odontoideum and review of the pertinent literature are presented. Objective To illustrate an unusual association of bipartite atlas and os odontoideum and explain the embryological basis. Summary of background data To the authors' knowledge, only one case of bipartite atlas with os odontoideum had been reported previously. Most of the previously reported cases of bipartite atlas are asymptomatic. Methods A 16-year-old boy presented with a 2-month history of weakness and numbness of all four limbs after sustaining a minor head trauma. Radiographs of cervical spine revealed aplasia of anterior arch of atlas, ventral displacement of C1 over C2 on flexion, which reduced on extension. CT scan showed anterior arch aplasia, posterior arch midline defect, and os odontoideum, which had a small projection on the anterior surface at the level of anterior arch. MRI demonstrated increased cord signal at C1-C2 levels on T2-weighted image. Transoral odontoidectomy and posterior fixation of occiput with C2-C3 spinous processes was performed. Results The patient had significant improvement over next 3 months. Conclusions We described a rare association of an anterior arch aplasia, posterior arch defect and os odontoideum. The natural history of patients with os odontoideum suggests that these people have a potentially precarious existence.

Bipartite atlas with os odontoideum: case report.

Congenital hypoplasia of the posterior arch of the atlas (C1), a developmental failure of chondrogenesis, is a rare anomaly and may range from partial clefts to total agenesis of the posterior arch. Ossification of the posterior arch usually occurs between the 3rd and 5th years of life. The incidence of posterior arch anomalies of the atlas is between 0.69% and 2.95%. For the evaluation of the patient, cervical lateral plain radiography, 2D or 3D reconstructed CT and MRI are very useful and important tools in initial diagnosis. Surgery is the treatment of choice in symptomatic compression. Excision of the posterior arch is performed. during surgery. After the surgery, patients may be followed up for instability and treated as necessary. A patient, admitted to the emergency department with head and neck trauma after a traffic accident is presented in this article. C1 hypoplasia was determined after detailed imagining studies and the radiology department consulted. When upper cervical anomalies are found in a young patient, the patient should be evaluated in detail with advanced radiological studies to avoid misinterpretation as fractures, luxation, osteolysis or instability. Consulting a radiologist could help making an accurate diagnosis and deciding on current therapeutic interventions.

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Congenital hypoplasia of the posterior arch of the atlas: case report and extensive review of the literature.

We describe CT and MRI of a previously unreported combination of atlantoaxial anomalies consisting of posterior arch hypoplasia in a bipartite atlas with an os odontoideum, in a 30-year-old woman presenting with neck and left arm pain. MRI showed the os odontoideum, marked stenosis of the spinal canal at the level of the atlas, with cord compression and evidence of myelopathy. CT revealed a bipartite atlas with midline clefts in anterior and posterior arches, thickening in the anterior arch and hypoplasia of the posterior arch with incurving of both hemiarches. Flexion and extension radiographs demonstrated atlantoaxial instability.

A rare cause of cervical spinal stenosis: posterior arch hypoplasia in a bipartite atlas.

We present CT and MR features of a large intracranial lipoma located in the left sphenocavernosal region in a patient with a history of spinal intradural lipoma excision. The lipomatous lesion surrounded the internal carotid artery and trigeminal nerve and extended extracranially into the infratemporal region through a smoothly dilated foramen ovale.

Ç. Atasoy

Papers

A rare cause of cervical spinal stenosis: posterior arch hypoplasia in a bipartite atlas.

Intracranial lipoma with extracranial extension through foramen ovale in a patient with encephalocraniocutaneous lipomatosis syndrome