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PubMed2004

Using fresh tissue dissection to teach human anatomy in the clinical years.

PURPOSE: Gross anatomy is taught in medical school with textbooks, cadaver dissection, plastic models, and multimedia illustration, but all lack the reality of color and texture that is possible with fresh tissue dissection. The authors studied the use of fresh tissue dissection of the thorax and abdomen of the rat to teach human anatomy. METHOD: In a half-day exercise, 52 fourth-year medical students paired off and completed an exercise to dissect in less than three hours the thorax and abdomen of a euthanized rat. Observation of organs was augmented by active manipulation such as passing a tube down the esophagus, cannulating the trachea and inflating the lungs, injecting dye in the kidney to trace the ureter and bladder, and pulling the testis through the inguinal canal. Comparison of the rat and human was emphasized to enhance the education. The exercise ended with practice suturing fresh tissue. RESULTS: Students rated the exercise to teach anatomy as 4.9 positive on a 5.0 (high) scale. The significant positive structures (p <.05) for texture were heart, liver, lungs and trachea; for color they were lungs and spleen; for location and size they were adrenal gland and urinary bladder; and for function they were adrenal gland and esophagus. CONCLUSION: Fresh tissue dissection of the thorax and abdomen of the rat is a valuable tool for human anatomy education. The dissonances in human and rat anatomy enhance abstraction and transfer of knowledge. Active manipulation of organs promotes retention of knowledge, and suturing provides a "clinical" context. Fresh tissue dissection is an efficient innovative method to provide a global review of anatomy of the thorax and abdomen during the busy clinical years of medical education.

Abdomen↗

PubMedDate not supplied

MR evaluation of chronic aortic dissection.

Thirty patients with suspected or known chronic aortic dissection were imaged with magnetic resonance (MR), CT, and angiography. Five of these patients had previously undergone surgical repair of the ascending aorta for a type A dissection. Magnetic resonance demonstrated an intimal flap and a double lumen in 25 cases. In four cases with a thrombosed false lumen, proved angiographically, an intimal flap and double channel were not seen. In two of four aortic dissections with a thrombosed false lumen, CT made the diagnosis by showing displaced intimal calcifications not visualized on MR. In one case the aortic dissection was made on CT and angiography but was not supported by MR which showed an aortic aneurysm, subsequently confirmed at surgery. Magnetic resonance, CT, and aortography differentiated between type A (nine patients) or B (20 patients) dissection in all cases and demonstrated extension into the abdominal aorta. Extension into the iliac arteries was seen on MR in three patients but missed in nine patients. Magnetic resonance differentiated the true and false lumen in all but one case. Thrombosis of the false channel was identified in four cases by a decrease in signal intensity on the second echo image. Cardiac gating and longitudinal contiguous sections seemed to be more suitable for appreciation of the relationships with arch vessels. Transverse contiguous slices allowed determination of the origin of celiac, mesenteric, and renal arteries from either the true or the false lumen. This study confirms that MR is an accurate and noninvasive method for the evaluation and follow-up of chronic aortic dissection, obviating the need for iodinated contrast media.

Aged↗

PubMed1993

Limitations of chest radiography in discriminating between aortic dissection and myocardial infarction: implications for thrombolysis.

It has been stated that chest radiographic features of aortic dissection are a contraindication to intravenous thrombolysis in patients with suspected acute myocardial infarction. Excluding aortic dissection could significantly delay such treatment in patients who would benefit from thrombolysis. Initial chest radiographs of 18 patients with acute aortic dissection and 25 patients with acute myocardial infarction were evaluated. The radiographs were studied by two experienced radiologists for signs of aortic dissection. No radiographic signs or combinations of signs accurately distinguished aortic dissection from myocardial infarction. Patients with chest radiographic signs suggesting aortic dissection but with clinical features suggesting myocardial infarction should not be denied the benefits of immediate intravenous thrombolysis.

Aortic Dissection↗

PubMed2001

Significance of retropharyngeal node dissection at radical surgery for carcinoma of the hypopharynx and cervical esophagus.

OBJECTIVES: To clarify the efficacy of dissection of retropharyngeal lymph nodes (RPLNs) in the surgical treatment of carcinoma of the hypopharynx and cervical esophagus. STUDY DESIGN: We started planned dissection of the RPLN during initial radical surgery in patients with squamous cell carcinoma of the hypopharynx or the cervical esophagus in 1988. Until 1997, we performed this procedure as a standard operation in 82 consecutive patients. METHODS: Mortality resulting from RPLN metastasis was compared between 82 patients who underwent RPLN dissection and 69 patients who did not undergo the procedure. RESULTS: Of 82 patients, 16 patients (20%) had positive RPLNs. These patients were at high risk of recurrence unless the node(s) were dissected. Although RPLN dissection did not improve the cumulative 5-year survival rate, it significantly decreased the number of patients who died of RPLN metastasis (chi2 = 3.68, P <.1). Four of the 16 patients who had positive RPLNs survived without any recurrence. CONCLUSION: Bilateral dissection of the RPLN during initial surgery is highly recommended in every surgical case of carcinoma of the hypopharynx and cervical esophagus.

Carcinoma, Squamous Cell↗

PubMed1998

Bilateral spontaneous dissection of the posteroinferior cerebellar arteries: case report.

OBJECTIVE AND IMPORTANCE: Cervicocerebral arterial dissections occur when blood extrudes into the wall of an artery supplying the brain. The resulting intramural hematoma may compromise the lumen and cause an aneurysmal dilation. Dissecting aneurysms are now recognized with increasing frequency as a cause of strokes. They usually occur spontaneously or are associated with trivial trauma to the artery. A dissecting aneurysm of the posteroinferior cerebellar artery (PICA) is very rare, however. We present a case with ischemic episode and successive subarachnoid hemorrhage caused by bilateral dissection of the PICAs. CLINICAL PRESENTATION: A 47-year-old man experienced sudden onset of cerebellar infarction that rapidly resulted in subarachnoid hemorrhage. Angiography revealed a typical pearl-and-string sign in the right PICA and an irregular stenosis in the left PICA. The patient died shortly after admission. Autopsy demonstrated bilateral dissection of the PICAs not involving the vertebral artery. CONCLUSION: The incidence of intracranial dissecting aneurysms most frequently occurs in the vertebral artery, but the PICA is only rarely involved, especially bilaterally. We are not aware of any other such case in the literature.

Aortic Dissection↗

PubMed1980

Functional radical neck dissection.

A technique is described for performing a radical neck dissection by elevating the muscle out of the neck to facilitate the complete removal of all the neck structures without injury to the muscle and without significantly increasing the operative time. The neck dissection can be performed as a "classical" radical neck dissection by removing all the neck structures en bloc, including the jugular vein and spinal accessory nerve. Alternatively, a "functional" radical neck dissection can be done in selected cases by dissecting out and preserving the jugular vein and/or the spinal accessory nerve. The sternal end of the sternocleidomastoid muscle is then reattached before closing the neck wounds. This technique was used unilaterally in 11 patients and bilaterally in 2 patients, without complications. The cosmetic results demonstrate a significant advantage of this method over the routine classical radical neck dissection. The results in this small series, with follow-up periods of 18 to 40 months in patients with squamous cell carcinoma, suggest that this procedure gives good results in selected cases.

Accessory Nerve↗

PubMed1982

Operative experience with 50 thoracic aortic dissections.

From 1971 to 1981, 46 patients were subjected to 50 operations (graft replacement, 31; patch aortoplasty, ten; suture aortorraphy, six; bypass, one; and nonthoracic vascular procedure, two) for thoracic aortic dissection. Four patients had two separate dissections. Dissections were classified as type A (ascending thoracic aortic, 38) or type B (descending thoracic aortic, 12) and subgrouped as acute (less than 2 weeks) or chronic (greater than 2 weeks). There were seven hospital deaths and an operative mortality of 14%. The operative mortality for acute type A dissections was 20% and for chronic type A, 7%. There was one operative death in the 12 type B dissections. Four of the seven deaths occurred in patients with an iatrogenic dissection. Overall cumulative survival was 70% at four years, but dropped to 45% at six years. Survival was poorest in the acute type A group and was only 38.9% at five years.

Adolescent↗

PubMedDate not supplied

Phenotypic modification of arterial smooth muscle cells in response to medial dissection.

BACKGROUND: In the treatment of peripheral arteries, percutaneous transluminal angioplasty is commonly associated with intimal tears and dissections. OBJECTIVE: To investigate the influence of medial dissection on the remodelling of the vessel wall after balloon injury. METHODS: Aortae were obtained from 14 Fauve de Bourgogne rabbits that had been fed a normal diet. Seven days after the initial pull-back injury, the aortae were examined using morphometric and immunocytochemical methods. RESULTS: Eight rabbits (57%) had a tear that extended into the media. Morphometric measurements showed that the intima was significantly thinner when there was a medial dissection [(18.3 +/- 6.9) x 10(-3) versus (39.1 +/- 3.5) x 10(-3) mm without dissection, P < 0.001]. In the media of injured vessels, medial dissection was associated with a greater accumulation of extracellular matrix proteins (50.5 +/- 9.7 versus 12.4 +/- 2.2% of the surface area), a marked reduction in alpha-smooth muscle actin content (36.6 +/- 5.4 versus 47.4 +/- 7.5% of the surface area), a higher expression of a smooth muscle activation antigen (21.2 +/- 5.7 versus 8.9 +/- 1.5% of the 2P1A2-immunostained surface area) and an increase in the number of medial proliferating cell nuclear antigen-positive nuclei (8.2 versus 1.2% of labelled nuclei). CONCLUSION: These observations indicated that mechanical injury of the arterial wall induces a phenotypic activation of medial smooth muscle cells. In the case of acute distension, the response of the smooth muscle cells in the media was mainly responsible for wound healing in the presence of medial dissection; moreover, acute distension induced a significant higher state of activation and a medial repairing that could prevent migration towards the intimal space.

Actins↗

PubMedDate not supplied

Early nodal response as a predictor for necessity of functional neck dissection after chemoradiation.

PURPOSE: Chemoradiation is increasingly becoming the standard of care for node-positive squamous cell cancer of the head and neck. Response to chemoradiation for clinically node-positive disease in the neck is often difficult to ascertain because clinical response may or may not be predictive of pathological response. This often leads to uncertainty about the necessity of a functional neck dissection after chemoradiation. In this study, we retrospectively analyzed a cohort of node-positive patients to examine pathological response as well as clinical outcome after chemoradiation with or without functional neck dissection. METHODS: Using the radiation oncology records from 1993 until 2003, a population of 420 patients with squamous cell cancer of the head and neck were identified. Of these, 34 patients were clinically node positive at the time of diagnosis and under went chemoradiation as their primary therapy. All patients received a concurrent platinum-based regimen. Median radiation dose to gross neck disease was 68.4 Gy (range: 50.4-73.8 Gy). RESULTS: Median follow-up time was 25 months (range: 4-88 months). Patients with a complete response (17/34, 50%) after receiving 50 Gy finished the full course of therapy but did not undergo functional neck dissection. Only one patient (1/17) in this observation group experienced relapse in the neck. Patients with a partial response who received 50 Gy (17/34) completed therapy and under went functional neck dissection, regardless of response at the end of therapy. Fifty percent (3/6) with positive pathology had a regional relapse in the neck, whereas only 1/11 patients with negative pathology relapsed in the neck. This result compared favorably with those who were observed after chemoradiation. CONCLUSIONS: Clinical response at 50 Gy can be an effective means of selecting patients for functional neck dissection. Patients with complete response at 50 Gy may be observed with a low regional recurrence rate. Those patients with a partial response should undergo adjuvant neck dissection.

Antineoplastic Combined Chemotherapy Protocols↗

PubMedDate not supplied

Acute and chronic aortic dissection.

Each year acute aortic dissection is diagnosed in 2,000 individuals in the United States. Acute aortic dissection is no longer a catastrophic event because this problem can be rapidly diagnosed with current medical technology, and therefore promptly treated with medication and surgery. Consequently, patients with aortic dissection can survive for 10 to 20 or more years after the initial event. However, there is considerable current debate regarding the most optimal technique(s) for the diagnosis of aortic dissection. Moreover, little information is available on the best methods for the long-term assessment and treatment of patients who have been successfully treated for acute aortic dissection. This report reviews the current techniques that are available for the diagnosis of aortic dissection and discusses the important issues regarding the acute and long-term treatment of patients with this problem.

Abdominal Pain↗

PubMed2005

Atraumatic vertebral artery dissection after cervical corpectomy: a traction injury?

STUDY DESIGN: Case report with review of the literature. OBJECTIVES: Presented is the first case of vertebral artery dissection secondary to intraoperative traction in cervical spine surgery. The pathogenesis and management of vertebral dissection in the immediate postoperative period are reviewed in detail. SUMMARY OF BACKGROUND DATA: Vertebral artery dissection is commonly associated with direct trauma, atraumatic or spontaneous. There are numerous reports of direct injury to the vertebral artery with cervical spine surgery, and it is a well-recognized risk. Cervical traction is also used routinely for improved placement of intervertebral devices/grafts. This is the first report of vertebral artery dissection occurring intraoperatively secondary to traction. The postoperative management is reviewed in detail. METHODS: Case study with extensive review of the literature. RESULTS: The patient underwent C6 corpectomy without intraoperative complications. Intraoperative wake-up test was normal. The patient remained intubated overnight for airway precautions. On postoperative day 1, the patient was lethargic and not following commands. Emergent CT of the brain and cervical spine revealed multiple posterior circulation infarcts with normal cervical spine and no hematoma. A stat angiogram revealed vertebral dissection. Medical management was initially attempted; however, infarcts continued, eventually requiring posterior fossa craniectomy/decompression and sacrificing the vertebral at the O-A junction. CONCLUSIONS: This is the first report of vertebral artery dissection occurring secondary to traction in cervical spine surgery. Surgeons must be aware that traction, even when performed appropriately, is not without risks. Anomalous vertebral arteries, osteophytes, and numerous other anatomic variants can lead to vertebral injury with traction.

Cervical Vertebrae↗

PubMed2006

Deep anterior lamellar keratoplasty using the manual dissection technique of Melles: a histopathologic correlation.

PURPOSE: To report the histopathologic findings in the host tissue of 2 human keratoconic corneas undergoing maximum-depth anterior lamellar keratoplasty (MDALK) using the manual dissection technique described by Melles. METHODS: Corneal buttons were examined from 2 patients with keratoconus who underwent MDALK using the manual dissection technique of Melles and converted to penetrating keratoplasty after rupture of the lamellar bed. Manual dissection was performed in 1 patient, and combined manual and viscoelastic dissection of Descemet membrane (DM) was performed in the other. RESULTS: Light microscopy of the corneal buttons showed a deep pre-Descemet dissection plane with minimal residual stroma. DM appeared to be thinned in both eyes and measured 3 to 8 microm in thickness. CONCLUSION: By using the manual dissection technique of Melles, LK can be performed exposing the smooth DM of the recipient bed. We confirmed exposure of DM in patient corneas, using this technique by light microscopy. There may be an increased risk of rupture of DM during surgery when this membrane is thinned, particularly in patients with keratoconus. This surgical technique allows conversion to penetrating keratoplasty after rupture of DM.

Adult↗

PubMed2004

Elective neck dissection and survival in patients with squamous cell carcinoma of the oral cavity and oropharynx.

OBJECTIVE/HYPOTHESIS: The utility of elective neck dissection in the management of patients with oral cavity and oropharyngeal cancer who present without neck metastases remains controversial. The study addressed the question of whether elective neck dissection improves regional control and survival in patients with squamous cell carcinoma of the oral cavity and oropharynx presenting with T1/T2 node-negative disease. STUDY DESIGN: A nonrandomized, uncontrolled retrospective chart review. METHODS: A nonrandomized, uncontrolled retrospective chart review was performed. Resection of the primary tumor was performed in all patients. The neck was observed in one group, and elective neck dissection was performed for patients in another group. RESULTS: The study data indicated that elective neck dissection significantly improves regional control and regional recurrence-free survival. Elective neck dissection when compared with observation of the neck did not improve overall survival. CONCLUSION: Elective neck dissection reduces regional recurrence and may extend disease-free survival.

Adult↗

PubMed2005

Shoulder disability after different selective neck dissections (levels II-IV versus levels II-V): a comparative study.

OBJECTIVES/HYPOTHESIS: The objective was to compare the results of clinical and electrophysiological investigations of shoulder function in patients affected by head and neck carcinoma treated with concomitant surgery on the primary and the neck with different selective neck dissections. STUDY DESIGN: Retrospective study of 40 patients managed at the Department of Otolaryngology, University of Brescia (Brescia, Italy) between January 1999 and December 2001. METHODS: Two groups of 20 patients each matched for gender and age were selected according to the type of neck dissection received: patients in group A had selective neck dissection involving clearance of levels II-IV, and patients in group B had clearance of levels II-V. The inclusion criteria were as follows: no preoperative signs of myopathy or neuropathy, no postoperative radiotherapy, and absence of locoregional recurrence. At least 1 year after surgery, patients underwent evaluation of shoulder function by means of a questionnaire, clinical inspection, strength and motion tests, electromyography of the upper trapezius and sternocleidomastoid muscles, and electroneurography of the spinal accessory nerve. Statistical comparisons of the clinical data were obtained using the contingency tables with Fisher's Exact test. Electrophysiological data were analyzed by means of Fisher's Exact test, and electromyography results by Kruskal-Wallis test. RESULTS: A slight strength impairment of the upper limb, slight motor deficit of the shoulder, and shoulder pain were observed in 0%, 5%, and 15% of patients in group A and in 20%, 15%, and 15% of patients in group B, respectively. On inspection, in group B, shoulder droop, shoulder protraction, and scapular flaring were present in 30%, 15%, and 5% of patients, respectively. One patient (5%) in group A showed shoulder droop as the only significant finding. In group B, muscle strength and arm movement impairment were found in 25% of patients, 25% showed limited shoulder flexion, and 50% had abnormalities of shoulder abduction with contralateral head rotation. In contrast, only one patient (5%) in group A presented slight arm abduction impairment. Electromyographic abnormalities were less frequently found in group A than in group B (40% vs. 85% [P = .003]), and the distribution of abnormalities recorded in the upper trapezius muscle and sternocleidomastoid muscle was quite different: 20% and 40% in group A versus 85% and 45% in group B, respectively. Only one case of total upper trapezius muscle denervation was observed in group B. In both groups, electroneurographic data from the side of the neck treated showed a statistically significant increase in latency (P = .001) and decrease in amplitude (P = .008) compared with the contralateral side. There was no significant difference in electroneurographic data from the side with and the side without dissection in either group. Even though a high number of abnormalities was found on electrophysiological testing, only a limited number of patients, mostly in group B, displayed shoulder function disability affecting daily activities. CONCLUSION: The study data confirm that clearance of the posterior triangle of the neck increases shoulder morbidity. However, subclinical nerve impairment can be observed even after selective neck dissection (levels II-IV) if the submuscular recess is routinely dissected.

Adult↗

PubMed2005

Postoperative bleeding after diathermy and dissection tonsillectomy.

OBJECTIVE: To analyze the incidence and pattern of bleeding after tonsillectomy performed by either cold dissection or diathermy. DESIGN: A prospective, nonrandomized cohort study of postoperative hemorrhage after tonsillectomy. METHODS: Monthly reporting of the number of tonsillectomies and postoperative bleeds from otolaryngologists working in rural areas of Victoria, Australia over a 2.5 year period. Criteria for bleeding were either 1) repeat anesthesia and surgery because of hemorrhage (including return to theater from the recovery room), or 2) readmission to hospital because of bleeding, or 3) blood transfusion to replace blood loss. Main outcome measures were the incidence, volume, and time course of postoperative hemorrhage. RESULTS: The number of bilateral tonsillectomies with removal by cold-blunt dissection was 3,087. In this group, there were 57 (1.85%) bleeds. The number of bilateral tonsillectomies with removal by diathermy dissection was 1,557. In this group, there were 37 (2.38%) bleeds. If cold dissection is taken as the "control" and diathermy tonsillectomy as the "treatment" group, the relative risk of bleeding after diathermy tonsillectomy is 1.30 (95% confidence interval 0.88-1.93). The pattern of bleeding after each technique differs significantly over time, with more reactionary bleeds in the dissection group and more bleeds between 4 to 7 postoperative days after diathermy. When bleeding occurred, it was in excess of 500 mL in 16% of dissection cases and 43% of diathermy tonsillectomies. CONCLUSIONS: The difference in the risk of bleeding after each technique did not reach statistical significance, but the temporal pattern of hemorrhage differed, and more bleeds exceeding 500 mL were seen in the diathermy group.

Adolescent↗

PubMed2006

Evidence of significant sternocleidomastoid atrophy following modified radical neck dissection type III.

BACKGROUND: Although modified radical neck dissection type III preserves the spinal accessory nerve, the internal jugular vein, and the sternocleidomastoid muscle, the authors believe there is a significant morbidity to retained structures after neck dissection. Although the effects on accessory nerve function and internal jugular vein patency have been documented, there is little information about sternocleidomastoid morphology and function following modified dissection. METHODS: Using a SonoSite ultrasound machine, the authors assessed sternocleidomastoid muscle morphology, at rest and during contraction, in a cohort of 45 patients who underwent modified radical neck dissection type III with no radiotherapy. All patients had head and neck cancers and received unilateral neck dissection as part of their primary treatment. Static and dynamic measurements were performed at three different levels of the muscle, with the neck in the neutral position. The contralateral neck of the same patient was used as a control. Local muscle asymmetry patterns were calculated using the Absolute Asymmetry Index. RESULTS: Significant sternocleidomastoid atrophy was noted on the side of modified radical neck dissection type III (p < 0.05). The atrophy was particularly marked in the caudal and middle portions of the sternocleidomastoid muscle and was likely related to damage to the segmental blood supply in the caudal and middle portions of the muscle as well as injury to the innervation. CONCLUSION: Despite evidence of significant atrophy, the muscle still underwent morphological changes during contraction that were comparable to those on the normal control side.

Accessory Nerve Injuries↗

PubMed1985

The preservation of shoulder function after radical neck dissection.

The most disabling side effect of radical neck dissection is the 'shoulder syndrome', caused by denervation of the trapezius muscle. This is due to division of the spinal accessory nerve, the motor nerve to the trapezius. Using cadaver dissections the anatomy of the cervical spinal nerve supply to the trapezius has been studied. At radical neck dissection stimulation of these cervical spinal nerves produced contraction of the trapezius muscle. Thus a modified technique of radical dissection has been developed preserving the cervical spinal nerves to the trapezius. Comparison of patients undergoing this modified radical neck dissection with patients undergoing a classical radical neck dissection shows them to have better shoulder function.

Accessory Nerve↗

PubMed2005

Perceptions of dissection by students in one medical school: beyond learning about anatomy. A qualitative study.

INTRODUCTION: The practice of dissection, as part of undergraduate medical education, has recently resurfaced in the public eye. This paper focuses on a number of important learning outcomes that were reported by Year 1-5 medical students in a British medical school, during the dissection sessions in the first 2 years of their training, as part of a wider qualitative research project into undergraduate medical education. METHODS: A group of 29 students was selected by quota sampling, using the whole student population of the medical school as the sampling frame. Qualitative data were collected by 1 : 1 interviews with students and from formal non-participatory observations of dissection sessions. RESULTS: Apart from learning to cope with the overt 'emotional confrontation' with the cadavers which assists anatomical learning, 7 additional covert learning outcomes were identified by the students: teamwork, respect for the body, familiarisation of the body, application of practical skills, integration of theory and practice, preparation for clinical work, and appreciation of the status of dissection within the history of medicine. DISCUSSION: A number of medical schools have either removed the practical, hands-on aspect of dissection in the medical undergraduate curriculum or are seriously considering such a measure, on financial and/or human resource grounds. This study highlights the fact that dissection can impart anatomical knowledge as well as offer other relevant, positive learning opportunities to enhance the skills and attitudes of future doctors.

Adult↗