Risk stratification for outpatient parathyroidectomy and predictors of postoperative complications

Introduction

The mainstay of treatment for primary hyperparathyroidism is surgery. Hypocalcemia after parathyroidectomy is common and poses a significant challenge, leading to increased patient morbidity and health care costs. While several groups have found predictor factors for hypocalcemia, none have created a risk stratification model. Here, we recognize important factors and optimal cut-off values that can allow risk stratification of patients.

Peripheral nerve regeneration in the apolipoprotein-E-deficient mouse

Apolipoprotein E (apo E) is thought to mediate the reutilization of myelin cholesterol for nerve regeneration. Prior research suggests that apo E is not essential for nerve regeneration following a nerve crush injury. This study was conducted to determine if apo E is essential for nerve regeneration after nerve transection and interposition nerve autograft. Nerve regeneration of transgenic apo E-deficient mice was compared with control mice after a sciatic nerve neurolysis and repair and interposition autograft. Histomorphometric assessment and histology were performed on distal nerve segments to evaluate nerve regeneration. Apo E-deficient mice demonstrated no difference in total fiber number or nerve fiber width when compared with controls; however, the nerve fiber density and percent neural tissue of apo E-deficient mice were significantly less than controls following nerve repair. Apo E deficiency does not affect nerve regeneration. It is likely that the low nerve fiber density and the low percent neural tissue associated with apo E-deficiency result from impairment in the disposal of myelin debris.     

Microvascular transfer of long tracheal autograft segments in the canine model

OBJECTIVE: The reconstruction of long segment tracheal defects represents an unsolved clinical dilemma. Prior attempts to directly revascularize tracheal segments have been unsuccessful. The objective of this study was to evaluate orthotopic autotransplantation of revascularized long tracheal segments in the canine model. METHODS: Ten randomly selected mongrel dogs underwent excision, orthotopic reimplantation, and microvascular revascularization of a long segment (8.0 cm) of cervical trachea. The cranial thyroid artery and the internal jugular vein served as the vascular supply for the tracheal segment. The animals were maintained for a period of 30 days during which time graft viability was measured by routine endoscopic assessment and tracheal biopsies. Ex vivo, tracheal autografts were examined grossly for graft healing an d microscopicallyfor histologic architecture. RESULTS: Seven of 10 dogs survived the predetermined 30-day postoperative study period without complications. Postmortem examination demonstrated that 7 dogs had healed tracheal autograft segments with normal histologic architecture, 2 dogs sustained a postoperative wound infection and tracheal dehiscence, and 1 dog sustained a fatal postoperative hematoma. CONCLUSIONS: For the first time, we have demonstrated direct revascularization of long segment tracheal autografts in the dog model using the cranial thyroid artery and internal jugular vein as the vascular supply.     

The thoracoacromial/cephalic vascular system for microvascular anastomoses in the vessel-depleted neck

OBJECTIVE: To review our experience with use of the thoracoacromial/cephalic (TAC) system in the free flap reconstruction of complicated head and neck defects. DESIGN: Case series. SETTING: Tertiary care referral center. POPULATION: A consecutive sample of 11 patients requiring free flap reconstruction of head and neck defects using the TAC system for microvascular anastomoses was identified by medical chart review. INTERVENTION: Free flap reconstruction of complicated defects of the head and neck using the TAC vascular system for microvascular anastomoses. MAIN OUTCOME MEASURES: Free flap survival and microvascular thrombosis. RESULTS: Of 11 patients using TAC anastomoses, all had complete survival of free flaps. No complications related to anastomotic failure were identified. CONCLUSIONS: The TAC system provides a reliable source of undisturbed vessels when cervical vessels are unusable or absent.     

Pretreatment with portal venous ultraviolet B-irradiated donor alloantigen promotes donor-specific tolerance to rat nerve allografts

OBJECTIVE: To determine if a single intraportal inoculation of ultraviolet B-irradiated (UVB) donor splenocytes can prevent nerve allograft rejection and confer donor-specific immunotolerance to rat nerve allograft segments. METHODS: Age-matched, class I and class II major histocompatibility complex (MHC) mismatched Buffalo (RT1b) rats were transplanted with a syngeneic nerve isograft, a Lewis (RT1l) nerve allograft, or a Brown-Norway (RT1n) rat nerve allograft segment. Control Buffalo rats in group I received a 3.0-cm Lewis (RT11) sciatic-posterior tibial interposition nerve allograft without pretreatment; group II Buffalo rats received a syngeneic Buffalo nerve isograft without pretreatment.Group III Buffalo recipients were inoculated with 2.5 x 107 UVB-irradiated Lewis donor splenocyte cells by portal venous administration 7 days before transplantation with a 3.0-cm sciatic-posterior tibial nerve allograft from a Lewis (RT11) or a third party Brown-Norway rat (RT1n) donor (group IV). Nerve graft regeneration was assessed with walking track analysis, nerve conduction studies, retrograde neural tracing, nerve graft histology, and morphometry. Recipient immune tolerance was assessed through in vitro immunological assessment. RESULTS: Pretreatment with UVB-irradiated donor splenocytes 7 days before transplantation prevented nerve allograft rejection. Pretreated animals receiving a nerve allograft recovered limb function, and demonstrated morphological, histological, and electrophysiologic parameters of nerve regeneration similar to that measured in rats receiving a nerve isograft. In vitro immunological assessment by mixed lymphocyte culture (MLC), cytotoxic T lymphocyte (CTL) assay, limiting dilution analysis (LDA) of helper (pTH) and cytotoxic (pCTL) precursor frequencies, and IL-2 production demonstrated a marked donor-specific suppression in allografted animals pretreated with intraportal UVB-irradiated donor splenocytes. These assessments correlated with indefinite acceptance of donor nerve allografts. CONCLUSIONS: A single pretreatment with a single intraportal dose of UVB-modified donor antigen specifically induces tolerance to peripheral nerve allografts in rats.     

Subcutaneous mandibulotomy: a new surgical access for large tumors of the parapharyngeal space

OBJECTIVES: Surgery for tumors of the parapharyngeal space (PPS) requires adequate exposure to identify and protect vital structures. Transcervical and transcervical-transparotid approaches to the PPS may be enhanced by mandibulotomy. However, midline mandibulotomy traditionally requires lip-splitting and extensive intraoral incisions, often necessitating tracheostomy and nasogastric feeding. We describe a new technique to gain exposure to the PPS while avoiding these consequences. STUDY DESIGN: Case series. METHODS: Five patients with PPS tumors underwent surgery using a new technique, the subcutaneous mandibulotomy approach (SMA). Each case was retrospectively assessed for tumor size, intraoperative access to the PPS, perioperative complications, and length of hospitalization. RESULTS: In this series, the additional exposure achieved by SMA was adequate to safely remove large PPS tumors that could not be delivered through the transcervical-transparotid approach. All patients started oral diets on postoperative day 1 and were discharged within 3 days. There were no intraoperative complications, and postoperative complications were self-limited. The pathologic entities were a venous malformation, a paraganglioma, and three large, deep-lobe pleomorphic adenomas of the parotid. CONCLUSIONS: We introduce a new technique, the SMA, which affords excellent access to the PPS without the lip-split, chin-split, and floor of mouth incisions. The SMA avoids both nasogastric feeding and a tracheostomy and offers improved cosmesis compared with a traditional midline mandibulotomy. Our current stepwise approach to achieve exposure to the PPS includes use of the SMA as an intermediate step for extensive PPS lesions, which are inaccessible through the transcervical approach yet do not require full labiomandibulotomy for safe and complete removal.     

Management of cancer of the retromolar trigone

Treatment of cancer of the retromolar trigone (RMT) is controversial. While early lesions may be managed with single-modality, more advanced lesions may invade the mandible, pterygoid musculature, and the adjacent mucosa of the tonsillar pillar and soft palate, therefore making therapeutic decisions more complicated. Treatment options traditionally include surgical resection, external beam irradiation, and combined modality therapy. The choice of therapy is dependent on the extent of the tumor, nodal metastasis, and the medical status of the patient and comorbid conditions. The following review outlines the current issues relevant to the diagnosis and therapy of patients with RMT malignancy.     

Bivalved palatal transposition flaps for the correction of acquired nasopharyngeal stenosis

Nasopharyngeal stenosis is almost universally an iatrogenic problem resulting from surgical trauma after adenotonsillectomy or uvulopalatopharyngoplasty (UPPP). In addition, laser-assisted uvulopalatopharyngoplasty for the treatment of snoring may lead to the development of cicatricial scarring and stenosis at the level of the velopharynx. The most common mechanisms implicated in the development of acquired nasopharyngeal stenosis are the overzealous removal of inferolateral adenoid tissue and excessive excision of the palatopharyngeal arches. Symptoms generally relate to a disturbance in respiration, olfaction, voice quality, and deglutition, and are often poorly tolerated. Surgical options for the correction of this challenging problem include steroid injections, scar lysis, skin grafts, Z-plasty repair, and the use of various local mucosal flaps. We report the successful use of bivalved palatal transposition flaps performed through the transoral route for the correction of severe acquired nasopharyngeal stenosis following UPPP in two patients. Both patients developed delayed nasopharyngeal stenosis following their initial surgery and subsequently failed several attempts at surgical correction of the stenosis, including laser lysis of the scarred soft palate. Using this technique of repair, both patients achieved satisfactory resolution of their symptoms, including comfortable nasal breathing and normal speech. We have found that this is a simple and effective technique for the correction of severe nasopharyngeal stenosis.