Motoyoshi Maruyama

Mumps virus infection in adults : Three cases of supraglottic edema

Mumps virus infections primarily involve the parotid glands and most frequently affect school‐aged children. We present three unusual adult cases of mumps with dyspnea secondary to severe swelling of the salivary glands and review previously reported cases in the literature. Dyspnea developed progressively after the onset of salivary gland swelling. Laryngoscopy revealed an advanced edematous change in the supraglottis obstructing the airway. In two cases, tracheotomy was needed because of rapid worsening of the supraglottic edema. Questioning regarding breathing problems and laryngoscopic examination is therefore recommended when one encounters a mumps case with combined parotid and salivary gland swelling.

MRI of intranasal pleomorphic adenoma

A pleomorphic adenoma in the nasal cavity constitutes a rarity. A 48-year-old woman presented with intranasal pleomorphic adenoma revealed by unilateral continuous obstruction and occasional epistaxis. Nasal endoscopy showed a mucosa-covered and opalescent polypoidal mass arising from the left nasal septum. Unlike cases affecting the major salivary gland, magnetic resonance image (MRI) revealed that the mass showed a low signal intensity on T1-weighted image and a heterogeneous, intermediate signal intensity on T2-weighted image. MRI findings can aid in diagnosis and help exclude the possibility of other neoplasms that occur at this site.

The effects of pitch tilt on postrotatory nystagmus in cats

When the head is tilted away from the upright position immediately after termination of earth-vertical axis (EVA) head rotation at a constant velocity, the rotation axis of postrotatory nystagmus (PRN) is gradually directed toward gravity (spatial reorientation). During roll tilt, the extent of the axis shift varies among species. In cats, the reorientation is limited to about 30-45 degrees of head tilt. In the present study, we examined features of PRN during pitch tilt in cats. The animals were rotated about EVA at a constant velocity of 100 degrees /s for 120 s. Within 2 s after stopping EVA rotation, the animals were tilted toward the pitch plane by as much as +/-90 degrees (nose-down or nose-up) in steps of 15 degrees. Eye movements were measured with 3D magnetic search coils. The angle of the PRN plane and its slow phase eye velocity (SPV) were measured. The duration of PRN decreased as pitch tilt increased regardless of whether the direction was nose-up or nose-down. The mean time constant of SPV was significantly longer for nose-up than for nose-down. PRN maintained its horizontal orientation without any vertical drift during pitch tilt, but there was little reorientation toward gravity. That is, no significant torsional component of SPV emerged to reorient the eyes according to gravity. Our results indicate that spatial reorientation depends on head orientation. For the PRN responses after pitch tilts in cats, the interactions of semicircular canal and otolith inputs in the central vestibular system might be vestigial.

Solitary Neurofibroma of the Floor of the Mouth: A Case Report

We present a case of a solitary neurofibroma of the floor of the mouth protruding into the submandibular region. A 51-year-old female presented with a 2-year history of swelling of the floor of the mouth. MRI revealed that the mass measuring 50 × 70 mm showed a homogenous, low signal intensity on a T1-weighted image and high signal intensity on a T2-weighted image. The tumor was completely removed through a cervical approach. Cases of a solitary neurofibroma originating from the floor of the mouth are extremely rare.

Effects of roll tilt on the direction of vertical postrotatory nystagmus in cats

The rotation axis of horizontal postrotatory nystagmus (PRN) changes as the head is tilted, so that it becomes directed toward gravity (spatial reorientation). Here, we examined the vertical PRN orientation during roll tilt in cats. Unlike the case in horizontal PRN, in vertical PRN no significant cross-coupled components emerged to reorient the eyes toward gravity. Our results indicate that otolith input contributes differently to horizontal VOR than to vertical VOR.

Directional preponderance of vertical eye movements induced by cross-axis adaptation of the vestibulo-ocular reflex in the cat

OBJECTIVE We examined the emerging vertical component after cross-axis vestibulo-ocular reflex (VOR) adaptation. METHODS For the adaptive conditioning, the whole body of a subject was rotated horizontally while a visual pattern was rotated vertically for 1h. RESULTS During the conditioning period, the vertical component in response to the vertical visual stimulation was an up-down asymmetric, and its amplitude gradually increased as the stimulus progressed. After conditioning, the direction of VOR was changed via an emerging vertical component during horizontal head rotation in total darkness. Even though the retinal slip-velocity was greater for downward than for upward during the conditioning period, the emerging upward component was significantly larger than the emerging downward component. CONCLUSION These results may be helpful for developing an optimal vestibular-compensation system by visual-vestibular mismatch/optokinetic training.

Adaptation of the vertical vestibulo-ocular reflex in cats during low-frequency vertical rotation

OBJECTIVE We examined plastic changes in the vestibulo-ocular reflex (VOR) during low-frequency vertical head rotation, a condition under which otolith inputs from the vestibular system are essential for VOR generation. METHODS For adaptive conditioning of the vertical VOR, 0.02Hz sinusoidal pitch rotation for one hour about the earths horizontal axis was synchronized with out-of-phase vertical visual stimulation from a random dot pattern. RESULTS A vertical VOR was well evoked when the upright animal rotated around the earth-horizontal axis (EHA) at low frequency due to the changing gravity stimulus and dynamic stimulation of the otoliths. After adaptive conditioning, the amplitude of the vertical VOR increased by an average of 32.1%. CONCLUSION Our observations showing plasticity in the otolithic contribution to the VOR may provide a new strategy for visual-vestibular mismatch training in patients with otolithic disorders. This low-frequency vertical head rotation protocol also provides a model for investigating the mechanisms underlying the adaptation of VORs mediated by otolith activation.