Tomoo Shatari

Pancreatobiliary Fistula Associated with an Intraductal Papillary-Mucinous Pancreatic Neoplasm Manifesting as Obstructive Jaundice : Report of a Case

We report a pancreatobiliary fistula caused by an intraductal papillary-mucinous pancreatic neoplasm (IPMN), manifesting as obstructive jaundice. Computed tomography showed dilatation of the bile duct and main pancreatic duct, with multiple cystic masses in the head of the pancreas. Endoscopic retrograde pancreatocholangiography showed a patulous papilla with mucin secretion. Contrast enhancement outlined amorphous material obstructing the lower part of the common hepatic duct. Pancreatogram and magnetic resonance cholangiopancreatography showed diffuse dilatation of the main pancreatic duct and side branches without communication with the adjacent organs or duct. We performed pancreaticoduodenectomy for IPMN of the pancreatic head and a tumor-like lesion in the lower common bile duct (CBD). Macroscopically, impacted thick mucus protruded into the CBD from the pancreas via a pancreatobiliary fistula. Histologic examination revealed a pancreatobiliary fistula caused by intraductal papillary-mucinous carcinoma of the pancreas with mucin hypersecretion, an adenoma without interstitial infiltration, and isolated implantation of an IPMN in the bile duct mucosa around the fistula.

Is histopathological evidence really essential for making a surgical decision about mucinous carcinoma arising in a perianal fistula? Report of a case.

We report an unusual case of mucinous adenocarcinoma of the anus associated with a chronic anal fistula, treated successfully by abdominoperineal resection (APR). Although multiple biopsies failed to reveal any histological evidence of malignancy, cancer was diagnosed from the mucin obtained for cytology. Subsequent histological examination of the resected specimen revealed clusters of cancer cells floating in a mucous lake, suggesting that it would have been difficult to acquire the cells in a biopsy sample. Conversely, the presence of mucin lakes and globules in specimens drained from the region of perianal sepsis may have been histologically informative for diagnosis. Thus, although biopsy of the lesion is undoubtedly essential for diagnosis, it often fails to provide enough information to make a definite diagnosis of mucinous carcinoma. This case illustrates that clinicians should base their decision on whether to perform surgery on clinical manifestations, imaging findings, and cytology of mucin obtained by drainage when it is difficult to obtain malignant cells by biopsy.

Reconstruction of anal function by transposed gracilis muscle with electrical stimulation: rabbit model.

For the reconstruction of anal function for fecally incontinent patients, it could be practicable to transpose the gracilis muscle around the anal canal, with electrical stimulation to maintain contraction. It is necessary to keep continuous tonus, so tetanic contraction or “summation” would be essential for fecal continence, with a stimulation which permits prolonged contraction. Transposition of the gracilis muscle around the rectum was performed in thirteen Japanese white male rabbits. The muscles of the conditioning group (n=8) were stimulated at 10 Hz for 6 weeks before the procedure. By stimulation at 15 Hz, a low frequency to permit prolonged contraction, the neoanal pressure increased maximally to 134.2 ± 55.6 cmH2O (mean ± s.d.) in the conditioning group, and to 115.0 ± 37.1 cmH2O in the non-conditionin group (n=5) (N.S.). But, the basal pressure with stimulation rose 82.3 ± 12.4% (mean ± s.d.) of the increase in the conditioning group, while that of the non-conditioning group remained at resting pressure (p<0.001). The conditioning made it possible for the rabbits gracilis muscle to create anal pressure with a sufficient rise in the basal pressure at a frequency permitting prolonged contraction.

A new approach to dynamic graciloplasty

Abstract: The reestablishment of anal function by transposition of the gracilis muscle, combined with the implantation of electrodes and a neuromuscular stimulator (dynamic graciloplasty), has recently been developed. With this method, the transposed muscle maintains contraction by electrical stimulation to maintain neoanal pressure without fatigue. It is necessary to convert the fatigue-prone gracilis muscle to fatigue-resistant muscle by long-term electrical stimulation (conditioning). In most patients receiving dynamic graciloplasty, the conditioning is accomplished after the transposition. However, conditioning before graciloplasty should reduce the risk of ischemia in the transposed muscle after the graciloplasty and improve the outcome. This new sequence of procedures is described, in combination with J-pouch construction, in a patient who required abdominoperineal excision of the rectum for lower rectal cancer. The graciloplasty was performed after conditioning of the gracilis muscle in situ; the conditioning did not cause the patient discomfort and resulted in good anal function.

How to convert the rabbit gracilis muscle into a neoanal sphincter.

For reconstruction of anal function in fecally incontinent patients, transposition of the gracilis muscle around the anal canal, with electrical stimulation to maintain contraction, seems practical. But the fast-twitch gracilis muscle is incapable of prolonged contraction without fatigue. Furthermore, the muscle must keep some tension between each stimulus. When the pressure decreases even transiently between stimuli, the neoanus cannot maintain continence. To fulfill these criteria, the neoanal sphincter must be stimulated at a frequency that can induce sufficient summation. We demonstrated that conditioning with long-term electrical stimulation will induce such summation at low frequency. The nerve to the gracilis muscle of rabbits was continuously stimulated at 5 Hz and 10 Hz for 4 to 8 weeks. This conditioning reduced the frequency necessary for summation, and conditioning at 10 Hz for 6 or 8 weeks induced sufficient summation (fusion index [FI] > 90%) at 20 Hz. The muscles conditioned at 10 Hz for 8 weeks showed sufficient summation (FI = 81%) at 15 Hz, a frequency that produced muscle contraction without fatigue, since even unconditioned muscle will remain contracted at 10 Hz without fatigue for 8 weeks. It is concluded that conditioning at 10 Hz for longer than 6 weeks produces enough summation at a low frequency stimulation to permit prolonged contraction.

Conversion of the rabbit gracilis muscle for transposition as a neoanal sphincter by electrical stimulation

To re-establish anal function in fecally incontinent patients it may be feasible to transpose the gracilis muscle around the anal canal, using electrical stimulation to trigger contraction. However, because the fast-twitching gracilis muscle is incapable of prolonged contraction without fatigue, it is necessary to convert it to a slow-twitching, fatigue-resistant muscle. We demonstrated this conversion by long-term electrical stimulation at low frequencies using a rabbit model. The nerve to the gracilis muscle was continuously stimulated at 2 Hz, 5 Hz, and 10 Hz for 2, 4, or 6 weeks. In the 6-week conditioning group, the percentage of type I fibers, identified by ATPase staining, increased as the conditioning frequency became higher, but the twitch contraction speed reduced with conditioning at a frequency of more than 5 Hz. The fatigue resistance improved by conditioning at 10 Hz, and conversion occurred in 6 weeks. Thus, we concluded that conditioning at 10 Hz for 6 weeks can convert rabbit gracilis muscle to a slow-twitching, fatigue-resistant muscle suitable for use as a neoanal sphincter.

Electrical stimulation for converting gracilis muscle to a fatigue-resistant power source and reconstruction of neoanal function

Transposition of gracilis muscle around anal canal and conversion of the properties to those suitable for the neoanal sphincter have been carried out using rabbits model. The muscle was converted to the fatigue-resistant after long-term electrical stimulation and it could maintain sufficient contraction. Feedback regulation of the neoanal pressure using a new electrical stimulation system was applied to attain the prolonged muscular contraction for keeping continence of neoanal function. The total system including implantable pressure sensor was highly effective for reconstructing the neoanal function.

Functional electrical stimulation for reconstruction of neoanal function

For reconstructing a neoanal function, it is necessary to convert the properties of the transposed gracilis muscle to the properties suitable for the neoanal sphincter. The muscle which was converted to a fatigue resistant form after long-term electrical stimulation can maintain contraction. Much strong stimulation causes muscle fatigue, so it is necessary to regulate neoanal pressure with moderate stimulation. Using rabbit models, the effects of long-term electrical stimulation for converting the muscle to a fatigue resistant form are discussed. An electrical stimulation system to regulate neoanal pressure is proposed.<<ETX>>