The necessity of level IIb dissection for clinically negative neck oral squamous cell carcinoma.

AIM: Selective neck dissection reduces the incidence of complications associated with radical neck dissection while achieving the same oncological results, especially in clinically node-negative (cN0) cases. The most common complications associated with selective neck dissection are spinal accessory nerve dysfunction and shoulder disability, which result from level IIb dissection. The aim of the present study was to evaluate the incidence of level IIb lymph node metastasis in cN0 oral squamous cell carcinoma (OSCC) patients to determine the necessity of selective neck surgery. METHODS: The medical records of 138 consecutive OSCC cN0 patients seen from June 2012 to June 2017 were retrospectively reviewed for age, gender, tumor localization, and TNM classification. RESULTS: The incidence of occult metastasis was 29.7%, but level IIb nodes were not involved in any case. DISCUSSION: The lack of involvement of level IIb nodes in occult metastasis, and high prevalence of shoulder dysfunction caused by injury to the spinal accessory nerve during surgery, challenge the necessity of surgical IIb node clearance in cNO OSCC; this is true for all stages and especially for early T1 stage cases, when the likelihood of occult lymph node metastasis is low (15.6%).

Type C botulism in dairy cattle from feed contaminated with a dead cat.

Four hundred twenty-seven of 441 adult Holstein dairy cattle from a 1,200-cow dairy died over a 1-week period during early spring 1998. Affected animals were from 4 late lactation pens, one of which included the bull string. Signs included weakness, recumbency, watery diarrhea, and death. Eighty animals from the 4 pens were dead approximately 8 hours after the first ill cows were noted. Affected cows would collapse on stimulation and extend all 4 limbs with moderate rigidity. Several lacked lingual tonus and had abdominal breathing patterns. The animals had been fed a load of total mixed ration that included a rotten bale of oat hay containing a dead cat. No common toxicants were identified, and pathologic examination revealed no consistent lesions. Testing of tissue from the cat carcass found in the feed sample using mouse protection bioassay identified the presence of type C botulinum toxin. Samples of feed, tissue from affected animals, cat tissue from feed, milk, and serum were also tested using an enzyme-linked immunosorbent assay (ELISA) specific for type C botulinum. Two samples of rumen contents were tested and found to be positive for botulism by ELISA, and 1 of 3 liver samples had a weak positive finding. No botulinum toxin was found in milk or sera using the ELISA.