Faculty Bibliography

OBJECTIVES: To present a rare case of facial nerve paraganglioma and novel use of a processed allograft for facial nerve reconstruction. STUDY DESIGN: Case report and review of the literature. METHODS: A 34 year old female presented with progressive onset right sided facial palsy for 5 months. CT and MRI demonstrated an irregular mass in the right facial nerve canal from the intratympanic segment to the stylomastoid foramen. RESULTS: Following transmastoid resection, the defect was repaired using processed allograft. Pathologic analysis was consistent with a paraganglioma. Facial nerve paraganglioma is a rare entity that has been reported only 10 times in the literature. CONCLUSIONS: Traditional methods of facial nerve reconstruction, including autologous and cadaveric grafting, can lead to significant patient morbidity. Autologous nerve grafts are the 'gold standard' for superior regenerative capability, but are limited by the length and potential neuroma formation at the donor site. Allogenic grafts from donors or cadavers have shown some efficacy, but can require immunosuppression. The Avance nerve graft is a cadaveric graft, processed and decellularized to maintain an extracellular matrix with laminin and intact endoneural tubes, thus providing support for the growing axon without generating an immune response. Initial studies of the Avance graft in animals and humans have examined repair of peripheral nerves, but this is the first reported case of human facial nerve reconstruction

OBJECTIVES: (1) Present a unique case of a thyroglossal duct cyst (TGDC) excised for recurrent infections with Trichinella spiralis in adjacent strap muscle; (2) review the literature regarding the diagnosis and treatment of subclinical trichinellosis of the head and neck. STUDY DESIGN: Case report and literature review. METHODS: Case report and literature review. RESULTS: We present the case of a male immigrant who suffered from recurrent midline neck infections due to aTGDC. The patient underwent an uneventful Sistrunk procedure. Histological examination of the surgical specimen revealed a chronically infected TGDC as well as remnants of skeletal muscle adjacent to the cyst containing nematode larvae, positively identified as Trichinella spiralis. The patient was subsequently evaluated by an infectious disease specialist and required no further treatment for his parasitic infection. DISCUSSION: The presence of nematode infections in developed countries is rare today given improved hygiene practices and control of meat quality. We present a unique case of incidentally noted Trichinella spiralis infection of the head and neck. To our knowledge, this is the first described case of trichinellosis of strap muscle adjacent to an excised TGDC and furthermore highlights the rarity of Trichinella spiralis infections of the head and neck. CONCLUSIONS: Trichinella spiralis may exist subclinically in a variety of human tissues including neck muscles

Spike-timing-dependent plasticity (STDP) has attracted considerable experimental and theoretical attention over the last decade. In the most basic formulation, STDP provides a fundamental unit - a spike pair - for quantifying the induction of long-term changes in synaptic strength. However, many factors, both pre- and postsynaptic, can affect synaptic transmission and integration, especially when multiple spikes are considered. Here we review the experimental evidence for multiple types of nonlinear temporal interactions in STDP, focusing on the contributions of individual spike pairs, overall spike rate, and precise spike timing for modification of cortical and hippocampal excitatory synapses. We discuss the underlying processes that determine the specific learning rules at different synapses, such as postsynaptic excitability and short-term depression. Finally, we describe the success of efforts toward building predictive, quantitative models of how complex and natural spike trains induce long-term synaptic modifications

While it has been appreciated for decades that synapse location in the dendritic tree has a powerful influence on signal processing in neurons, the role of dendritic synapse location on the induction of long-term synaptic plasticity has only recently been explored. Here, we review recent work revealing how learning rules for spike-timing-dependent plasticity (STDP) in cortical neurons vary with the spatial location of synaptic input. A common principle appears to be that proximal synapses show conventional STDP, whereas distal inputs undergo plasticity according to novel learning rules. One crucial factor determining location-dependent STDP is the backpropagating action potential, which tends to decrease in amplitude and increase in width as it propagates into the dendritic tree of cortical neurons. We discuss additional location-dependent mechanisms as well as the functional implications of heterogeneous learning rules at different dendritic locations for the organization of synaptic inputs