H. Wayne Slone

Assessment of the lingual nerve in the third molar region using magnetic resonance imaging

PURPOSE The purpose of this study was to determine the precise in situ location of the lingual nerve in the third molar region using high-resolution magnetic resonance imaging. PATIENTS AND METHODS Ten healthy volunteers (20 sides) with mandibular third molars underwent bilateral axial and coronal high-resolution magnetic resonance imaging (MRI) examinations of the posterior mandible and floor of the mouth from the lingula to the mental foramen. Three trained individuals made measurements of each image to determine the vertical and horizontal position of the lingual nerve in the third molar region. RESULTS The mean vertical (2.75 +/- 0.97 mm [range, 1.52-4.61]) and horizontal (2.53 +/- 0.67 mm [range, 0.00-4.35]) distances to the lingual crest and lingual plate of the mandible were determined. In the third molar region, there were only 2 of 20 cases (10%) in which the nerve was above the lingual crest, and there were 5 of 20 instances (25%) in which the nerve was in direct contact with the lingual plate. CONCLUSIONS This study precisely documents the in situ location of the lingual nerve in the third molar region, and reconfirms the relative vulnerable position of this structure during third molar surgery.

Extradural dermoid tumor of the petrous apex

Dermoid cysts are rare, benign, congenital tumors. Most case series thus far have featured intradural tumors. The authors report on a case of an extradural dermoid tumor of the middle cranial fossa with osseous invasion, successfully removed using a left subtemporal extradural approach. The clinical presentation, histological features, radiological findings, and management of this unique case are described.

Spinal Myxopapillary Ependymoma Metastatic to Bilateral Internal Auditory Canals

Objectives We report a rare case of spinal myxopapillary ependymoma metastatic to both internal auditory canals (IACs) and its implications for diagnosing neurofibromatosis type 2 (NF2). Methods We present a detailed clinical history, magnetic resonance imaging (MRI), intraoperative photographs, and histopathologic findings from a patient with bilateral IAC lesions, and review the diagnostic criteria for NF2. Results An 11-year-old boy with surgically resected spinal myxopapillary ependymoma, treated with total spine irradiation for recurrence, later showed bilaterally enhancing IAC lesions on T1-weighted MRI with contrast. The diagnosis of NF2 with bilateral vestibular schwannomas was entertained. Close examination of T2-weighted MRI, however, demonstrated the masses to be isointense to cerebrospinal fluid. This finding raised the possibility of other, more unusual IAC lesions. The patient underwent sequential suboccipital craniotomies for tissue diagnosis, and both IAC lesions were found to be myxopapillary ependymomas. Conclusions This is the youngest reported patient with metastatic myxopapillary ependymoma. Although vestibular schwannomas account for the majority of contrast-enhancing T1-weighted IAC lesions, other uncommon lesions may present in a similar manner. A T2 fast-spin echo screening MRI would have missed this patients lesions. Therefore, both T1-weighted MRI with or without contrast and T2-weighted MRI may be necessary to distinguish vestibular schwannoma from other, more unusual IAC lesions.

Masses of the Sellar and Junxtasellar Region

Tumors of the sellar and junxtasellar regions are common, accounting for in excess of 10–15% of all intracranial tumors [1]. Although the majority of these are benign tumors, mostly pituitary adenomas, they can account for significant morbidity and a shortened life expectancy. Pituitary adenomas are the most common sellar and suprasellar masses in adults, with meningiomas being the second most common. In children, craniopharyngiomas and chiasmatic/hypothalamic gliomas account for the vast majority of lesions in this region. Adenomas, meningiomas, craniopharyngiomas, chiasmatic/hypothalamic gliomas, and aneurysms account for 75% of sellar and junxtasellar masses [2]. Although the focus of our discussion is tumors, some nonneoplastic entities are discussed, since these can be difficult to distinguish from tumors and must be differentiated, since the treatment approach can be very different.

Gunshot wounds of the brain: Influence of ballistics and predictors of outcome by computed tomography

Gunshot wounds of the head commonly are encountered in the practice of emergency radiology. Radiologists play a vital role in the initial evaluation of patients who present after a gunshot injury and can guide the neurosurgeons approach to surgery and the forensic pathologists collection of evidence. It is useful to understand the ballistics that influence missile course and would potential for accurate assessment of injury patterns that occur in gunshot wounds to the head. Additionally, it is imperative to recognize important prognostic findings on computed tomographic imaging to ensure optimal management of the patient.

MRI with Magnetic Resonance Spectroscopy of multiple brain abscesses secondary to Scedosporium apiospermum in two immunocompromised patients

Scedosporium apiospermum is a deadly fungal infection that can infect the central nervous system, particularly in immunocompromised patients. We present two cases of Scedosporium brain abscesses. The first case was fatal and relevant conventional MRI and MR spectroscopy findings are discussed. To our knowledge, this is the first reported case of MR spectroscopy in Scedosporium apiospermum abscesses. In the second case, the patient recovered and conventional MR findings are followed over several months. In the appropriate clinical setting, conventional MR imaging and MR spectroscopy may facilitate diagnosis, earlier initiation of antifungal pharmacotherapy and surgical intervention in this frequently fatal infection.

Chordomas and Other Skull Base Tumors

The list of differential considerations of lesions of the central skull base is long and includes many common tumors such as meningiomas and metastatic disease, which are discussed elsewhere in this book. In this chapter, we review the differential list of skull base tumors and discuss in more detail chordomas and to a lesser degree chondrosarcomas, two rare malignant lesions that classically involve the skull base. Although magnetic resonance imaging (MRI) has become the examination of choice in evaluation of intracranial tumors, in the skull base, computed tomography (CT) and MRI have complementary roles. CT is better at defining the complex bony anatomy and extent of bony involvement and MRI, because of its superior soft tissue contrast and multiplanar capability, is better at delineating the location, anatomic extension, and defining involvement of adjacent, critical neural, and vascular structures such as the cavernous sinus, optic chiasm, basilar artery and brain stem, for example. Although imaging studies cannot reliably distinguish chordoma from chondrosarcoma or other skull base lesions, defining the location and extent of the lesion are important factors in determining the optimal the surgical approach and in effective treatment planning. This is critical given that radical resection is the key factor in longer survival and improved quality of life.

Chapter 41 – Primary Central Nervous System Lymphoma

The incidence of primary central nervous system lymphoma (PCNSL) has increased over the past several decades. The prevalence continues to remain higher in the immunocompromised than immunocompetent population. Despite advances in therapy, the prognosis remains poor with PCNSL. Early diagnosis and initiation of appropriate therapy is important for the long-term prognosis. Clinical presentations are variable, and neuroimaging plays a key role in suggesting the diagnosis. Computed tomography generally demonstrates iso- or hyperdense masses that homogeneously enhance. On magnetic resonance imaging, which is the study of choice, the lesions are typically iso- or hypointense on T1 and T2 sequences, and again enhance with contrast. The lesions may also demonstrate restricted diffusion on diffusion-weighted imaging, due to their dense cellularity. The cerebral hemispheres are the most common location, but the deep gray matter and corpus callosum are also frequently involved. Imaging patterns vary between immunocompetent and immunocompromised patients, with the latter group more likely to have multiple lesions and ring enhancement patterns related to central necrosis. Alternative imaging modalities may play a role in the diagnosis in certain circumstances. Numerous variations of PCNSL have been described, and are also discussed in this chapter.

Chapter 51 – Papillary Glioneuronal Tumors

Papillary glioneuronal tumors are rare, typically low-grade brain tumors that usually present with seizure activity. Pathologically, they are characterized by gliovascular pseudopapillary structures, composed of astrocytes and neuronal appearing cells. On computed tomography and magnetic resonance imaging, they are most often noted in the supratentorial region, and have a benign appearance, with cystic and solid components, and minimal if any surrounding edema or infiltration. Enhancement is a common feature. Rarely, the tumor can appear more aggressive, and demonstrate peritumoral edema and mass effect.

Pituitary and Sellar Region Lesions

Abstract Lesions of the sellar, parasellar, and suprasellar regions are common and account for up to 20% of all intracranial neoplasms. Of these, pituitary adenomas are the most common in adults, accounting for over 50% of all lesions in this region. Magnetic resonance imaging has become the imaging examination of choice in this region given its multiplanar capabilities, superior soft-tissue contrast and resolution, and lack of beam hardening artifact seen with computed tomography. The other imaging modalities play a more limited role in answering specific questions related to the lesions. Although there is considerable overlap in the imaging characteristics of the many lesions that can occur in this region, we will attempt to identify imaging characteristics of the lesions that are classic and allow for a more accurate preoperative diagnosis. The type, location, and extent of the lesion are important factors in determining the optimal surgical approach and in effective treatment planning.