Ricardo Izquierdo

Refinements using free-tissue transfer for complex cranial base reconstruction.

Resection of skull base tumors may sometimes result in massive extirpation defects that are not amenable to local tissue closure. Closure of large basicranial defects can be performed with either a myocutaneous, a deepithelialized myocutaneous, or a simple muscle free flap designed from the ample rectus abdominis vascular territory. This free-tissue donor site has abundant and reliable well-vascularized tissue that can easily be customized to seal these tenuous areas. The rectus abdominis muscle and its vascularized territory were used in 18 of 19 consecutive patients at our center to close basicranial ablation defects. Of these, 6 were rectus abdominis muscle flaps, 5 were myocutaneous rectus abdominis flaps, and 7 were deepithelialized rectus abdominis muscle flaps. All free flaps survived. The intracranial space was sealed successfully in all but one patient. This patient underwent reconstruction with a muscle free flap and had a postoperative cerebrospinal fluid leak. This complication could have been avoided by using a deepithelialized myocutaneous flap to obliterate the central dead space with the vascularized subcutaneous fat. Two patients experienced minor wound infections, and one had a subdural abscess that was fully contained by a free flap placed over the duraplasty. One patient had a donor-site hernia. There was no incidence of meningitis. Knowledge of the anatomy of the vascular territory of the deep inferior epigastric vessels can be used judiciously to secure three-dimensional reconstruction of the skull base. The donor site supplies ample tissue for reconstruction and allows individual tailoring for obliteration of geometrically complex extirpation defects in and around the cranial base without the need to reposition the patient. (Plast. Reconstr. Surg. 92: 567, 1993.)

Transplantation of lymph node fragments in a rabbit ear lymphedema model : A New method for restoring the lymphatic pathway

&NA; The treatment of lymphedema by medical or surgical means remains a difficult task, and no technique is presently satisfactory. We established a rabbit ear chronic lymphedema model in which sequential lymph node fragments were transplanted to restore lymphatic pathways. Twenty New Zealand White rabbits were divided into two groups of 10 animals. One group served as the control, and the other was the transplantation group. A 3‐cm‐wide strip of skin and subcutaneous tissue including all the lymphatics was excised circumferentially from the root part of the right ear in each rabbit. The vascular pedicle in the control group was wrapped with a “bridge” strip of skin from the ventral ear to protect it from drying. In the transplantation group, the auricular lymph node was harvested from the contralateral ear, cut into 1‐ to 2‐mm slices, and implanted next to the vascular pedicle where the lymph vessels had been resected. Water displacement measurements in both groups revealed significant edema (p < 0.001) compared with the contralateral ear at 3 days. Peak swelling was observed at 10 days in both groups. Volumes decreased in both groups postoperatively. The volume measured as percentage change in the lymph node transplantation group was significantly lower than in the control group at 2 months and continuing to the end of the experiment (p < 0.001). Indirect lymphographic examination revealed that the distal lymphatic vessels of the control group were increased in number, dilated, and did not allow proximal passage of dye. Light microscopy revealed the vascular pedicle to be surrounded by dense scar tissue in the “bridge.” The transplantation group showed free passage of dye through the bridge. Microscopic examination showed regenerated lymphoid tissue with sinuses along the artery and vein of the “bridge.” Many channels with a layer of endothelial cells were also noted. Electron microscopy confirmed these sites to be regenerated lymph vessels. Lymphatic tissue can regenerate after fragment transplantation. This lymph tissue seems to regenerate lymphatic vessels that may function for drainage. The results suggest that this simple technique may be applicable in a clinical situation to prevent or treat obstructive lymphedema. (Plast. Reconstr. Surg. 101: 134, 1998.)

Comparative study on the use of anticoagulants heparin and recombinant hirudin in a rabbit traumatic anastomosis model

Antithrombotic drugs, such as heparin, have been used in the clinics for a long time. Heparin acts by binding with antithrombin III to form a complex thereby enhancing the activity of antithrombin III to inactivate coagulation factors IIa, IXa, Xa, XIa and XIIa. Hirudin is a new antithrombotic agent and is reported to be much more powerful than heparin on a gravimetric basis. When both are administered systemically, one of the common complications seen is bleeding. Some previous studies have shown that local vascular endothelial concentrations of heparin are 30 to 7500 times greater than those found in the circulating blood. In order to avoid such complications, topical administration of antithrombotic drugs may be an ideal route of administration. The rabbit ear arterial crush-avulsion thrombosis model was used in this study. The animals were divided into five groups: one control group and four treatment groups which received varying concentrations of heparin and hirudin. In the saline control group, the patency rate was 19.23% at 24 hrs and 15.38% at 7 days. A higher patency rate at 7 days was obtained in groups treated with high concentration of heparin and hirudin. ACT, PT and APTT performed on samples drawn one hour after drug administration were within the normal range in both the control and the treatment groups. Scanning electron microscopy revealed the different extent of the clots on the injured intimal surfaces of the vessels in different groups. The results indicate that high concentrations of topically administered heparin or hirudin minimize the systemic complications and maximize the antithrombotic effects.

TOPICAL APPLICATION OF LOW MOLECULAR WEIGHT HEPARIN IN A RABBIT TRAUMATIC ANASTOMOSIS MODEL

Low molecular weight heparins (LMWHs) are antithrombotic drugs composed of lower molecular weight components of heparin with an apparent molecular weight in the range of 4.0-8.0 KDA. These agents have been used clinically for several years. They have different mechanisms of action compared to heparin, a longer half-life and much higher bioavailability. Anticoagulant drugs such as heparin have been used topically in our previous studies to avoid bleeding complications observed with systemic administration. In this study, low molecular weight heparin (Certoparin, Sandoz) was topically administered in a rabbit ear arterial crush-avulsion thrombosis model and compared with heparin. The animals were divided into three groups: LMWH, heparin and saline control groups. In the LMWH group, the patency rate was 71% (10 of 14) at both 1 and 7 days. The patency rate in the heparin group was 95% (19 of 20) at 24 hrs and 80% (16 of 20) at 7 days. In the saline control group, the vessel patency rate was 17% at 24 hrs and 13% at 7 days. Clotting times such as ACT, PT and APTT performed on samples drawn one hour after drug administration were within the normal ranges for both the control and the treatment groups. The results suggest that topical administration of LMWH prevents the occurrence of thrombosis at the traumatic anastomosis site to a similar degree as heparin.

En Bloc Resection of an Ethmoid Carcinoma Involving the Orbit and Medial Wall of the Cavernous Sinus

The involvement of the cavernous sinus by malignant tumors has limited their surgical treatment. We report here a successful en bloc resection of an invasive ethmoid carcinoma involving the cavernous sinus in a 46-year-old man. To prepare for surgery on this patient, a cadaver study was performed to investigate the feasibility of en bloc cavernous sinus resection and reconstruction. The preoperative evaluation, operative approach, and postoperative management are presented.

Complex cranial base trauma resulting from recreational fireworks injury : case reports and review of the literature

Two patients who sustained complex skull base trauma secondary to recreational fireworks injuries are reported. Initial assessment and management included axial and coronal computerized tomography, control of hemorrhage, debridement of wound and brain, isolation of brain from external environment, and reconstruction of the cranial base floor. Secondary orbital and facial reconstruction used available bone fragments and iliac bone graft in one patient and vascularized free tissue transfer in the other. In both patients, reconstruction of both the intracranial and extracranial compartments was successful with acceptable cosmetic result. Modification of multiple conventional approaches, along with a multispecialty surgical team, was used to deal effectively with these unique cases.

Comparative study of protease inhibitors on coagulation abnormalities in canine pancreatitis

Coagulation abnormalities induced by pancreatitis were studied in 36 dogs. The 12 dogs in group I underwent a duodenotomy alone. The six dogs in groups II, III, IV, and V had pancreatitis induced by bile injection (1 cc/kg) into the pancreatic duct. Twenty minutes after bile-induced pancreatitis, group III was given 1.0 mg/kg aprotinin (trasylol), group IV was given 10 mg/kg S-2441, a new synthetic protease inhibitor, and group V was given 0.5 mg/kg alpha 2-antitrypsin by intravenous infusion over 10 min. Blood was drawn for amylase, protime (PT), partial thromboplastin time (PTT), fibrinogen, and platelets, in addition to markers of hypercoagulation, fibrinopeptide A, and antithrombin III, and markers of fibrinolysis, B beta 15-42 immunoreactive peptide (IP), and alpha 2-antiplasmin at baseline, 1/2, 1, 3, 6, 24, 48, and 72 hr after duodenotomy or bile injection. There was no significant difference in PT, platelets, antithrombin III, and fibrinopeptide A among the five groups. With the induction of pancreatitis (group II), serum amylase was significantly elevated but fibrinogen only became elevated at 24 hr and PTT at 48 hr. The increase in B beta 15-42 IP seen 30 min after induction of pancreatitis and the decrease in alpha 2-antiplasmin were blunted by aprotinin, alpha 1-antitrypsin, and S-2441, but inhibition of the rise in amylase and B beta 15-42 IP only reached significance with S-2441 (P less than 0.05). Pancreatitis-induced fibrinolysis was inhibited by S-2441 suggesting that synthetic protease inhibitors may play a therapeutic role in pancreatitis.