Retropharyngeal abscess due to Fusobacterium necrophorum complicated by progressive internal carotid artery stenosis and multiple cranial nerve palsies.

BACKGROUND: A case of retropharyngeal abscess complicated by both artery and nerve injury has rarely been reported. METHODS: A 36-year-old woman suddenly presented with right eye visual loss, dilated pupil, reduced direct light reflex, ptosis and ocular motility disorder on the side of inflammation progression, and was diagnosed with retropharyngeal abscess due to Fusobacterium necrophorum. The patient was treated only with antibiotics and, no further surgery was necessary but tracheotomy. Four months later, MRA showed right ICA occlusion and left ICA stenosis. MRI revealed continuous spread of inflammation due to the abscess from the retropharyngeal to the intracranial space. RESULTS: These severe complications would be attributed to an endothelial damage to the arterial wall and an ischemic neuropathy caused by inflammation and thrombogenesis due to Fusobacterium necrophorum. CONCLUSIONS: This case should provide a better understanding of the mechanism of vascular and cranial nerve injury due to retropharyngeal infections, and highlights the need for early antibiotic therapy and repeated vascular evaluation.

Excitatory subtypes of the lateral amygdala neurons are differentially involved in regulation of synaptic plasticity and excitation/inhibition balance in aversive learning in mice.

The amygdala plays a crucial role in aversive learning. In Pavlovian fear conditioning, sensory information about an emotionally neutral conditioned stimulus (CS) and an innately aversive unconditioned stimulus is associated with the lateral amygdala (LA), and the CS acquires the ability to elicit conditioned responses. Aversive learning induces synaptic plasticity in LA excitatory neurons from CS pathways, such as the medial geniculate nucleus (MGN) of the thalamus. Although LA excitatory cells have traditionally been classified based on their firing patterns, the relationship between the subtypes and functional properties remains largely unknown. In this study, we classified excitatory cells into two subtypes based on whether the after-depolarized potential (ADP) amplitude is expressed in non-ADP cells and ADP cells. Their electrophysiological properties were significantly different. We examined subtype-specific synaptic plasticity in the MGN-LA pathway following aversive learning using optogenetics and found significant experience-dependent plasticity in feed-forward inhibitory responses in fear-conditioned mice compared with control mice. Following aversive learning, the inhibition/excitation (I/E) balance in ADP cells drastically changed, whereas that in non-ADP cells tended to change in the reverse direction. These results suggest that the two LA subtypes are differentially regulated in relation to synaptic plasticity and I/E balance during aversive learning.