Evaluation of subjectivity in the interpretation of videonystagmography.

CONCLUSION: Subjectivity seems to play a definite role in the interpretation of the pendular test, but somewhat less for caloric testing, where pure visual analysis seems to be more reliable. Automated values provided by proof-tested software may be useful. OBJECTIVES: In some centers, the interpretation of videonystagmography is still based on direct visual analysis of recorded tracings. Our study addresses the importance of subjectivity in the interpretation of videonystagmographic readings. PATIENTS AND METHODS: Two experts (one junior and the other senior) were asked to interpret the same caloric and pendular tests on two different occasions, 3 months apart. Initial reading was performed without knowledge of the patient's history or the results of other neuro-otological tests. Three months later, interpretations were done with complete access to the patient's charts. The experts' answers were compared to the values provided by the computer software. RESULTS: For the pendular test, inter-expert agreement was poor. With knowledge of the patient's history, the expert's interpretations tended to coincide with the software's calculations. For the caloric test, interpretation was less variable.

Unilateral focal polymicrogyria in a patient with classical Aarskog-Scott syndrome due to a novel missense mutation in an evolutionary conserved RhoGEF domain of the faciogenital dysplasia gene FGD1.

Faciogenital dysplasia or Aarskog-Scott syndrome (AAS) is an X-linked disorder characterized by craniofacial, skeletal, and urogenital malformations and short stature. Mutations in the only known causative gene FGD1 are found in about one-fifth of the cases with the clinical diagnosis of AAS. FGD1 is a guanine nucleotide exchange factor (GEF) that specifically activates the Rho GTPase Cdc42 via its RhoGEF domain. The Cdc42 pathway is involved in skeletal formation and multiple aspects of neuronal development. We describe a boy with typical AAS and, in addition, unilateral focal polymicrogyria (PMG), a feature hitherto unreported in AAS. Sequencing of the FGD1 gene in the index case and his mother revealed the presence of a novel mutation (1396A>G; M466V), located in the evolutionary conserved alpha-helix 4 of the RhoGEF domain. M466V was not found in healthy family members, in >300 healthy controls and AAS patients, and has not been reported in the literature or mutation databases to date, indicating that this novel missense mutation causes AAS, and possibly PMG. Brain cortex malformations such as PMG could be initiated by mutations in the evolutionary conserved RhoGEF domain of FGD1, by perturbing the signaling via Rho GTPases such as Cdc42 known to cause brain malformation.

[Cochlear implant or regular hearing aid?]. / Appareillage acoustique ou implantation cochléaire: les cas limites.

A significant number of deaf patients that have received cochlear implants now achieve higher word recognition scores then those with conventional auditory prostheses. This situation makes the choice of which type of auditory rehabilitation to propose a complex matter in patients with remaining auditory function. Our paper aims at providing some arguments to these new questions by presenting the clinical experience and practice of the Centre romand d'implants cochléaires. We also address related legal issues. Clinical tools, such as testing the comprehension of lists of logatoms have proved very useful for the evaluation of these particular patients. The evaluation of cochlear implant candidates remains a highly individualized process, necessitating a case by case approach by an experienced multidisciplinary cochlear implant team.

Anesthesia management in a young child with aromatic l-amino acid decarboxylase deficiency.

Aromatic l-amino acid decarboxylase (AADC) deficiency is characterized by an almost complete absence of sympathetic autoregulation, because of very low levels of circulating catecholamines. Here, we report the successful management of four consecutive anesthesia procedures in a young child presenting with AADC deficiency. Our experience suggests that, with appropriate anticipation of the potential autonomic disturbances, anesthesia, at least for minor surgical and diagnostic procedures, can be conducted safely in patients with AADC deficiency.

Projections from the spinal trigeminal nucleus to the cochlear nucleus in the rat.

The integration of information across sensory modalities enables sound to be processed in the context of position, movement, and object identity. Inputs to the granule cell domain (GCD) of the cochlear nucleus have been shown to arise from somatosensory brain stem structures, but the nature of the projection from the spinal trigeminal nucleus is unknown. In the present study, we labeled spinal trigeminal neurons projecting to the cochlear nucleus using the retrograde tracer, Fast Blue, and mapped their distribution. In a second set of experiments, we injected the anterograde tracer biotinylated dextran amine into the spinal trigeminal nucleus and studied the resulting anterograde projections with light and electron microscopy. Spinal trigeminal neurons were distributed primarily in pars caudalis and interpolaris and provided inputs to the cochlear nucleus. Their axons gave rise to small (1-3 microm in diameter) en passant swellings and terminal boutons in the GCD and deep layers of the dorsal cochlear nucleus. Less frequently, larger (3-15 microm in diameter) lobulated endings known as mossy fibers were distributed within the GCD. Ventrally placed injections had an additional projection into the anteroventral cochlear nucleus, whereas dorsally placed injections had an additional projection into the posteroventral cochlear nucleus. All endings were filled with round synaptic vesicles and formed asymmetric specializations with postsynaptic targets, implying that they are excitatory in nature. The postsynaptic targets of these terminals included dendrites of granule cells. These projections provide a structural substrate for somatosensory information to influence auditory processing at the earliest level of the central auditory pathways.

An animal model for cochlear implants.

OBJECTIVE: To test the feasibility of using the deaf white cat model of early-onset deafness. We studied the neuronal effects of prosthetic intervention with a clinical, "off-the-shelf" multichannel cochlear implant. METHODS: We placed cochlear implants in 5 deaf white kittens at age 12 and 24 weeks. The devices were activated and stimulated in the laboratory using a clinical speech processor programmed with a high-resolution continuous interleaved sampling (CIS) strategy for 8 to 24 weeks. Stimulus parameters were guided by electrically evoked brainstem responses and intracochlear-evoked potentials. Kittens were assessed with respect to their tolerance and general behavior in response to speech, music, and environmental sounds. RESULTS: Surgical complications were minimal, and kittens tolerated the experimental procedures well. Subjects were able to detect and respond to a specific sound played from a computer speaker. Electrophysiologic responses were reliably attainable and showed consistency with observed behavioral responses to sound. This experimental paradigm, using clinical devices, can be used in a practical research setting in cats. CONCLUSIONS: Deafness and other variations in neural activity result in many distinct changes to the central auditory pathways. Animal models will facilitate assessment of the reversibility of deafness-associated changes at the level of the neuron and its connections. Our observations of the feasibility of using clinical devices in animal models will enable us to simulate clinical conditions in addressing questions about the effects of "replacement" activity on the structure and function within the central auditory pathways in deafness.

Multimodal inputs to the granule cell domain of the cochlear nucleus.

There is growing evidence that hearing involves the integration of many brain functions, including vision, balance, somatic sensation, learning and memory, and emotional state. Some of these integrative processes begin at the earliest stages of the central auditory system. In this review, we will discuss evidence that reveals multimodal projections into the granule cell domain of the cochlear nucleus.

Standardized uptake value of 2-[(18)F] fluoro-2-deoxy-D-glucose in predicting outcome in head and neck carcinomas treated by radiotherapy with or without chemotherapy.

PURPOSE: In patients with head and neck cancer enrolled onto a prospective study of positron emission tomography (PET), pretreatment 2-[(18)F] fluoro-2- deoxy-D-glucose (FDG) uptake was evaluated as a predictor of local control and disease-free survival (DFS) after treatment by radiotherapy (RT) with or without chemotherapy. PATIENTS AND METHODS: We studied 63 patients with carcinomas of the head and neck who had an FDG-PET scan before radical RT. Tumor FDG uptake was measured with the semiquantitative standardized uptake value (SUV). All patients but one were treated with accelerated or hyperfractionated RT schedules. Thirteen patients received concomitant cisplatin-based chemotherapy. RESULTS: In 25 patients who presented with any component of treatment failure, the SUV was significantly higher than in the remaining patients without any such failure. Patients having tumors with high FDG uptake had a significantly lower 3-year local control (55% v 86%, P =.01) and DFS (42% v 79%, P =.005) compared with patients having low uptake tumors. In the multivariate analysis, the only factor that retained its significance for DFS was SUV category, whereas T category was of borderline significance. For local control, T category remained a significant factor, whereas a lower local control was observed for tumors with a high SUV compared with those with low SUV. CONCLUSION: FDG uptake, as measured by the SUV, has potential value in predicting local control and DFS in head and neck carcinomas treated by RT. High FDG uptake may be a useful parameter for identifying patients requiring more aggressive treatment approaches.