First bite syndrome (FBS) manifests is characterized by severe parotid pain triggered by the first bite of food, with or without muscle spasms. The pain typically diminishes with subsequent bites. We report a case of 32-year-old male with Marcus-Gunn syndrome (30-year history), no prior head or neck surgery, tumors, infections, or temporomandibular joint disease. Since age of 15, he experiences bilateral parotid pain and spasms exclusively upon consuming ice cream in high ambient temperatures post-summer exercise. Symptoms resolve spontaneously within 30 s and persist despite trials of heat therapy, massage, and physiotherapy. While approximately 42% of FBS cases have identifiable etiology, others implicate aberrant activity in the auriculotemporal, greater auricular, or cervical sympathetic nerves. In this patient, symptoms occur only with cold food ingestion in hot environments, suggesting involvement of the trigeminal nerve's mandibular branch in oral thermosensation. To our knowledge, this is the first reported case linking FBS symptoms to temperature sensation.

Mulvihill-Smith Syndrome (MSS) is a clinically complex and genetically unsolved nano-rare disorder with only 12 patients reported in the literature. Most patients (91%) have immunological impairments, succumb to infection, and might develop cancer later in life. Its pathogenesis remains elusive and therapeutic options are limited. We used single-cell MULTI-omics (sc-MULTI-omics), combining transcriptomics (gene expression, TCR, and BCR repertoire) and proteogenomic (Cellular Indexing of Transcriptomes and Epitopes by Sequencing; CITE-seq), to decipher the pathophysiology of nano-rare disease patient. We report a new patient who is a 16-year-old girl. She had an increased leukocyte counts and typical manifestations of MSS such as short stature, older appearance, multiple pigmented nevi, microcephaly, monolateral keratoconus, Marcus-Gunn syndrome, hearing loss, vitamin D deficiency, mild hypercortisolism, and diabetes mellitus with very high insulin resistance (T3DM). sc-MULTI-omics CITE-seq showed that the MSS patient had increased central memory CD4+ T cells as well as effector memory CD8+ T cells, whilst reduced naïve T cells (both CD4+ and CD8+ T cells). Furthermore, we identified genes and pathways associated with the progeria-like phenotype, inflammation, and cancer progression, which may contribute to the clinical signs of MSS. sc-MUTLI-omics CITE-seq analyses improve our understanding of complex human disease pathophysiology and provides an alternative approach in personalized medicine in nano-rare disease.

This case report describes the Marcus Gunn phenomenon (MGP), an infrequent type of congenital unwanted contractions of facial muscles that occurs in 4%-6% of patients with congenital ptosis. The defining characteristic of MGP is the affected eyelid lifting in a manner similar to the opening of the mouth. It addresses a 45-year-old man who was examined in the dental clinic with a severely decayed tooth. He exhibited evidence of normal vision and synchronous movement of his lips and eyelid. The conditions matched those of the autosomal dominant disorder with incomplete penetration, the MGP. The carious tooth was restored without the necessity for any surgical intervention. The patient was given appropriate dental treatment without any surgical intervention for Marcus Gunn Syndrome. After receiving routine fillings to treat dental caries, the patient stopped complaining of pain. This case report reveals insight into a situation that has been speculated to be an example of neural redirection syndrome, in which impulses from the trigeminal nerve's motor unit are naturally redirected into the levator palpebrae superioris muscles of the upper eyelid and the superior pterygoid muscle.

Poking palpebral conjunctiva evoked upper-eyelid retraction during ophthalmic surgery. Iatrogenic eyelid ptosis occurred if eyelid branch of lachrymal nerve was sectioned. Mesencephalic trigeminal nucleus (Vme) neurons were labeled when tracer injected into lachrymal nerve innervating eyelid Mueller's muscle. Masseter afferent Vme neurons projecting to oculomotor nucleus (III) was observed in toad and rat, which helps amphibians to stare prey when they open mouth widely to prey. We hypothesized single Vme neurons may have peripheral collaterals to both eyelid and masseter muscles. WGA-594 was injected into upper eyelid, and WGA-488 was simultaneously delivered into ipsilateral masseter muscle in the same rat. Then, double labeled Vme neurons were found under both conventional and confocal microscope. Meanwhile, contact of WGA-594 positive eyelid afferent Vme neurons with WGA-488 labeled masseter afferent ones were observed sometimes. Combined with our previous observation of oculomotor projection Vme neurons, we thought WGA-594/488 double labeled Vme cells, at least some of them, are oculomotor projecting ones. Contact between eyelid and masseter afferent Vme neurons are supposed to be electrotonically coupled, based on a line of previous studies. If exogenous or genetic factors make these Vme neurons misinterpret masseter input as eyelid afferent signals, these Vme neurons might feedforward massages to eyelid retractor motoneurons in the III. Besides, oculomotor projecting Vme neurons might be co-fired by adjacent masseter afferent Vme neurons through electrotonic coupling once the masseter muscle is activated. In these cases, Marcus Gunn Syndrome might occur. This finding leads to a new hypothesis for the Syndrome.