Soft tissue attenuation in middle ear on HRCT: Pictorial review.

Middle ear disease is a common clinical entity; imaging, especially High resolution Computed Tomography (HRCT), plays a crucial role in diagnosis and assessing the disease extent, helping to decide appropriate management. Temporal bone imaging is challenging and involves thorough understanding of the anatomy, especially in relation to HRCT imaging. Most of the middle ear pathologies appear as "soft tissue" on imaging. Careful analysis of the soft tissue on the HRCT is crucial in achieving the right diagnosis; clinical information is essential and the imaging findings need correlation with clinical presentation and otoscopic findings. The purpose of this pictorial essay is to enlist the pathologies that present as soft tissue in middle ear and to provide a structured and practical imaging approach that will serve as a guide for confident reporting in daily practice.

Congenital absence of optic chiasm: demonstration of an uncrossed visual pathway using monocular flash visual evoked potentials.

A 35 month old child was referred for electrophysiology testing with pendular nystagmus, corresponding head oscillations and reduced vision. Flash visual evoked potential (VEP) revealed large responses at the right occiput (but not the left occiput) from the right eye and similar large responses at only the left occiput from the left eye, indicating absent/deficient crossover at the chiasm. A magnetic resonance imaging (MRI) scan subsequently confirmed absence of the optic chiasm. There was no other evidence of midline brain defects. Her subsequent development to age 11 has been followed. The nystagmus has remained mainly horizontal but a torsional component was noted from age 5 years and described as see-saw at age 6 years. A small right esotropia was noted at 6 years and spectacles prescribed for low hypermetropic refractive error. Bilateral superior rectus recessions at age 7 years produced an improved head posture. Her visual acuity has remained stable at around 6/24 from age 4 years. No binocularity nor stereopsis has been demonstrated over subsequent visits.

Diagnosis of an intracranial arteriovenous malformation using extracranial carotid Doppler sonography.

Carotid sonography is a well-established technique in the evaluation of patients with neurologic symptoms. We describe the case of a woman in whom duplex Doppler sonography of the extracranial carotid circulation showed high-velocity diastolic flow and a low resistance index without turbulence or morphologic abnormality of the artery. A suspected cause of this finding was low-resistance distal circulation secondary to low-resistance intracranial circulation due to an arteriovenous malformation. This diagnosis was later confirmed by CT. Because of the significant risk of bleeding associated with an asymptomatic intracranial arteriovenous malformation, duplex Doppler sonographic findings suggesting a low-resistance waveform in the presence of a morphologically normal carotid artery should prompt further imaging.