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Michael Lim

Publications and source records attributed to Michael Lim.

At least 19 recordsLinked to original sources
PubMed2026

Structured robotic colorectal training in a non-tertiary NHS hospital: a 502-case consecutive cohort implementation study.

Robotic-assisted colorectal surgery has expanded rapidly across NHS practice in the UK. Structured unit-wide training pathways are essential for safe technology adoption, yet published outcome data from non-tertiary hospitals remain limited. This study describes the implementation and feasibility of a unit-wide robotic colorectal program at a high-volume non-tertiary hospital, reporting outcomes across 502 consecutive resections performed by eight consultant surgeons and presenting these in the context of nationally published benchmarks. A retrospective cohort study of 502 consecutive robotic colorectal resections performed at York Teaching Hospital between May 2022 and December 2025. Eight consultant surgeons (A-H) participated in a structured four-phase training pathway incorporating simulation training, proctored cases, complexity-based case progression, and formal credentialing. Primary outcomes were 30-day mortality, unplanned return to theatre (RTT), and anastomotic leak (AL). Anastomotic leak was calculated using only patients who underwent anastomosis as the denominator. Procedure-stratified and individual surgeon outcomes with 95% confidence intervals were reported. Risk-adjusted cumulative sum (RA-CUSUM) analysis was performed to evaluate learning curves. Outcomes are presented descriptively alongside nationally published reference data; no formal statistical comparison against national benchmarks was performed. 502 robotic colorectal resections were performed. Mean patient age was 70.0 ± 11.3 years; 58.4% were male. Median ASA grade was III. The indication was malignancy in 89.2% of cases. Length of stay was non-normally distributed and is therefore reported using median and interquartile range in the revised analysis. Key outcomes: - 30-day mortality: 1.0% (5/502; 95% CI 0.4-2.3%) - Unplanned return to theatre (RTT): 5.2% (26/502; 95% CI 3.6-7.5%) - Anastomotic leak (AL): 3.3% (15/450; 95% CI 2.0-5.5%; denominator = patients with anastomosis) - 30-day unplanned readmission: 5.0% (25/502; 95% CI 3.4-7.2%) - Conversion to open surgery: 3.6% (18/502; 95% CI 2.3-5.6%) - Lymph node yield ≥12: 91.3% of cancer resections - R0 resection rate: 95.1% of cancer resections All primary outcomes fell within or below the published reference ranges used for descriptive context. RA-CUSUM trajectories were heterogeneous: no surgeon crossed the predefined upper control limit, but several curves showed later upward movement. Accordingly, the analysis is interpreted as safety surveillance rather than evidence of uniform performance improvement. RA-CUSUM monitoring showed that no surgeon crossed the predefined upper control limit; however, heterogeneous trajectories precluded a claim of uniform performance improvement.

Humans↗
PubMed2006

Cerebral perfusion imaging in vasospasm.

Vasospasm following cerebral aneurysm rupture is one of the most devastating sequelae and the most common cause of delayed ischemic neurological deficit (DIND). Because vasospasm also is the most common cause of morbidity and mortality in patients who survive the initial bleeding episode, it is imperative not only to diagnose the condition but also to predict which patients are likely to become symptomatic. The exact pathophysiology of vasospasm is complex and incompletely elucidated. Early recognition of vasospasm is essential because the timely use of several therapeutic interventions can counteract this disease and prevent the occurrence of DIND. However, the prompt implementation of these therapies depends on the ability to predict impending vasospasm or to diagnose it at its early stages. A number of techniques have been developed during the past several decades to evaluate cerebral perfusion, including positron emission tomography, xenon-enhanced computed tomography, single-photon emission computed tomography, perfusion- and diffusion-weighted magnetic resonance imaging, and perfusion computed tomography. In this article, the authors provide a general overview of the currently available perfusion imaging techniques and their applications in treating vasospasm after a patient has suffered a subarachnoid hemorrhage. The use of cerebral perfusion imaging techniques for the early detection of vasospasm is becoming more common and may provide opportunities for early therapeutic intervention to counteract vasospasm in its earliest stages and prevent the occurrence of DINDs.

Cerebrovascular Circulation↗
PubMed2006

Phase I/II trial of an allogeneic cellular immunotherapy in hormone-naïve prostate cancer.

PURPOSE: To determine the toxicity, immunologic, and clinical activity of immunotherapy with irradiated, allogeneic, prostate cancer cells expressing granulocyte macrophage colony-stimulating factor (GM-CSF) in patients with recurrent prostate cancer. PATIENTS AND METHODS: A single-institution phase I/II trial was done in hormone therapy-naïve patients with prostate-specific antigen (PSA) relapse following radical prostatectomy and absence of radiologic metastases. Treatments were administered weekly via intradermal injections of 1.2 x 10(8) GM-CSF gene-transduced, irradiated, cancer cells (6 x 10(7) LNCaP cells and 6 x 10(7) PC-3 cells) for 8 weeks. RESULTS: Twenty-one patients were enrolled and treated. Toxicities included local injection-site reactions, pruritus, and flu-like symptoms. One patient had a partial PSA response of 7-month duration. At 20 weeks post first treatment, 16 of 21 (76%) patients showed a statistically significant decrease in PSA velocity (slope) compared with prevaccination (P < 0.001). Injection site biopsies showed intradermal infiltrates consisting of CD1a+ dendritic cells and CD68+ macrophages, similar to previous clinical trials using autologous GM-CSF-transduced cancer cells. Posttreatment, patients developed new oligoclonal antibodies reactive against at least five identified antigens present in LNCaP or PC-3 cells. A high-titer antibody response against a 250-kDa antigen expressed on normal prostate epithelial cells was induced in a patient with partial PSA remission; titers of this antibody decreased when treatment ended, and subsequent PSA relapse occurred. CONCLUSIONS: This non-patient-specific prostate cancer immunotherapy has a favorable safety profile and is immunologically active. Continued clinical investigation at higher doses and with longer boosting schedules is warranted.

Aged↗
PubMed2006

Clinical and subclinical leaks after low colorectal anastomosis: a clinical and radiologic study.

PURPOSE: This study was designed to examine the natural history of subclinical leaks and their effect on bowel function and quality of life and to evaluate water-soluble contrast enema features that predict anastomotic healing after leaks. METHODS: Consecutive patients who underwent low rectal anastomosis were followed up postoperatively for leaks. All leaks were confirmed radiologically with CT scanning and water-soluble contrast enema imaging. Water-soluble contrast enemas were serially repeated to identify healing. Characteristics on initial water-soluble contrast enema were correlated with observed healing. Postoperatively, patients were required to fill in a quality of life and a bowel function questionnaire. RESULTS: A total of 138 patients underwent low rectal anastomosis procedures with a median follow-up period of 26 (interquartile range, 19-37) months. There were 23 documented leaks of which 13 (9 percent) presented clinically and 10 (8 percent) presented subclinically. Ileostomy closure was possible in 4 of 13 (30 percent) patients with a clinical leak and all 10 (100 percent) patients with a subclinical leak. Median quality of life scores were lower for patients with clinical leaks and no ileostomy closure (P = 0.03). Bowel function for subclinical leak patients and clinical leak patients with ileostomy closure were similarly impaired. The presence of a cavity (P = 0.01) and a stricture (P = 0.01) at the anastomotic site were unfavorable radiologic features associated with nonhealing. CONCLUSIONS: Subclinical leaks are more benign in their natural history compared with clinical leaks. Quality of life and bowel function is no better in patients with a subclinical leak compared with patients with a clinical leak who have ileostomy closure. Anastomotic leaks may resolve if favorable radiologic features are present.

Aged↗
PubMed2006

CyberKnife radiosurgery for extremity schwannomas: technical note and case report.

Peripheral nerve sheath tumors are uncommon. Although surgical resection remains the treatment of choice for most symptomatic lesions, the potential for intraoperative injury to the nerve is not insignificant. This concern is of particular relevance in those patients with a genetic proclivity to develop multiple peripheral nerve sheath tumors. Here we report four symptomatic peripheral extremity schwannomas all in 1 patient who was treated with CyberKnife radiosurgery. The radiosurgical Dmax in each case was between 24.4 and 25.32 Gy. At 1-year follow-up, patient symptoms had been ameliorated, no tumor had increased in size and there was no compromise in neurological function. Although this experience is still very preliminary, it represents the first published description of a peripheral nerve sheath tumor being treated with stereotactic radiosurgery.

Adult↗
PubMed2006

New vessel formation in the central nervous system during tumor growth, vascular malformations, and Moyamoya.

In the normal adult brain, blood vessel formation is tightly down-regulated. However, pathologic processes such as brain tumors can increase the proportion of endothelial cells involved in angiogenesis. When this process is initiated, a complex series of timed events result in new vessel formation. In this review, we will describe the process of angiogenesis in the central nervous system. We will discuss the roles of Vascular Endothelial Growth Factor (VEGF), Fibroblast Growth Factor (FGF), Angiopoietins, Platelet Derived Growth Factor (PDGF), and integrins in angiogenesis. We will also look into their significance in disease processes such as neoplasms, arteriovenous malformations (AVM), and Moyamoya disease.

Angiopoietins↗
PubMed2006

Stereotactic radiosurgery using CT cisternography and non-isocentric planning for the treatment of trigeminal neuralgia.

OBJECTIVE: Frame-based radiosurgical rhizotomy has been shown in clinical studies to be effective for managing trigeminal neuralgia (TN). To date, however, only a small pilot study has been published for the frameless, image-guided CyberKnife system. We present our preliminary experience with 29 trigeminal neuralgia patients treated with the frameless CyberKnife using X-ray image-guided targeting, a novel CT method for target definition, and non-isocentric planning. MATERIALS AND METHODS: All 29 patients failed previous medical therapy and 14 had undergone prior surgical procedures. CT iohexal cisternography was used to identify the 6- to 8-mm segment of nerve to be lesioned. The marginal dose ranged from 60 to 70 Gy (median 66.4 Gy) as defined at an average 79th percentile. The corresponding Dmax varied from 71.4 to 86.4 Gy (median 77.91 Gy). RESULTS: After a median 10-month follow-up, 26 of 29 (90%) patients rated their pain control as excellent and 3 (10%) reported no improvement. Median time to improvement was 6 days. No or only minor progression in numbness was reported by 22 of 29 (76%) patients, 4 of 29 (14%) patients reported worsening, and 3 of 29 (10%) reported the onset of severe ipsilateral facial numbness. Two patients whose target volume inadvertently included the semi-lunar ganglion developed painful dysethesias in the distribution of their numbness. CONCLUSION: Although the optimal dose and length of nerve to be lesioned are still being refined, this preliminary experience suggests that image-guided robotic radiosurgery can effectively lesion the trigeminal nerve. Further follow-up is needed to determine whether our method has advantages over the more commonly used procedure for radiosurgical trigeminal rhizotomy.

Adult↗
PubMed2005

Characterization of the integrin alpha v beta3 in arteriovenous malformations and cavernous malformations.

BACKGROUND: Alpha V beta 3 (alphavbeta3) is an integrin specifically expressed on the endothelial cells of central nervous system (CNS) neoplasms. However, no data exist on the expression of alphavbeta3 in vascular malformations of the CNS. In this study, we investigate the expression of alphavbeta3 in arteriovenous malformations (AVMs) and cavernous malformations (CMs). METHOD: Frozen samples of AVMs from 12 patients and CMs from 5 patients were obtained intraoperatively. Once the final pathology had been confirmed, immunohistochemistry was performed using an antibody to the integrin alphavbeta3. The alphavbeta3 expression pattern was graded according to the percentage of positively staining vessels. RESULTS: Ten of 12 AVMs demonstrated alphavbeta3 immunopositivity. Six of these 10 AVMs had moderate or strong staining. Most notably, 5 of the 6 moderate or strongly staining AVMs came from patients 22 years of age or younger. Four of these 6 AVMs had previously been embolized. None of the cavernous malformations demonstrated alphavbeta3 immunopositivity. DISCUSSION: alphavbeta3 may contribute to the formation of AVMs in younger patients. alphavbeta3 may also provide a potential therapeutic target. The lack of alphavbeta3 expression in cavernous malformations, despite their high vascular densities, suggests that the pathophysiology of their formation differs from that of AVMs.

Adolescent↗
PubMed2005

CyberKnife radiosurgery for idiopathic trigeminal neuralgia.

OBJECT: Gamma knife surgery is an accepted treatment option for trigeminal neuralgia (TN). The safety and efficacy of CyberKnife radiosurgery as a treatment option for TN, however, has not been established. METHODS: Forty-one patients were treated between May 2002 and September 2004 for idiopathic TN at Stanford University and the Rocky Mountain CyberKnife Center. Patients with atypical pain, multiple sclerosis, or previous radiosurgical treatment or a follow-up duration of less than 6 months were excluded. Patients were evaluated for the level of pain control, response rate, time to pain relief, occurrence of hypesthesia, and time to pain recurrence with respect to the length of the nerve treated and the maximum and the minimum dose to the nerve margin. Thirty-eight patients (92.7%) experienced initial pain relief at a median of 7 days after treatment (range, 24 hours-4 months). Pain control was ranked as excellent in 36 patients (87.8%), moderate in two (4.9%), and three (7.3%) reported no change. Six (15.8%) of the 38 patients with initial relief experienced a recurrence of pain at a median of 6 months (range 2-8 months). Long-term response after a mean follow-up time of 11 months was found in 32 (78%) of 41. Twenty-one patients (51.2%) experienced numbness after treatment. CONCLUSIONS: CyberKnife radiosurgery for TN has high rates of initial pain control and short latency to pain relief compared with those reported for other radiosurgery systems. The doses used for treatment were safe and effective. Higher prescribed doses were not associated with improvement in pain relief or recurrence rate. The hypesthesia rate was related to the length of the trigeminal nerve treated.

Adult↗
PubMed2005

alpha(v)beta(3) Integrin in central nervous system tumors.

alpha(v)beta(3) Is an integrin specifically expressed in endothelial cells of newly forming blood vessels. Integrin-mediated angiogenesis is hypothesized to play a central role in the development and the progression of central nervous system neoplasms. Accordingly, it is considered a potential target for antiangiogenic therapy. In the current study, we compare the expression of alpha(v)beta(3) in ependymomas, oligodendrogliomas, pilocytic astrocytomas, medulloblastomas, and vestibular schwannomas (acoustic neuromas). Samples of 5 tumors of each of the 5 tumor types were harvested surgically and frozen. After the pathological diagnosis was confirmed, immunohistochemistry was performed using an anti- alpha(v)beta(3) monoclonal antibody (LM609). The expression of alpha(v)beta(3) was assessed using a 4-tiered (0-3) grading scheme reflecting the percentage of positively staining vessels. All vestibular schwannomas demonstrated strong (grade 3) alpha(v)beta(3) expression. The expression was uniformly prominent in Antoni B regions of the tumors. Of 5 ependymomas, 4 demonstrated uniformly strong alpha(v)beta(3). Oligodendrogliomas, medulloblastomas, and pilocytic astrocytomas demonstrated more variable alpha(v)beta(3). alpha(v)beta(3) may contribute significantly to angiogenesis in vestibular schwannomas and ependymomas. Despite the high vascular density of oligodendrogliomas, pilocytic astrocytomas, and medulloblastomas, these tumors had variable moderate alpha(v)beta(3) expression. This discrepancy suggests temporal and/or regional variability in the angiogenesis in these types of tumor. This study provides the first demonstration of alpha(v)beta(3) expression in vestibular schwannomas, medulloblastomas, and pilocytic astrocytomas.

Astrocytoma↗
PubMed2005

The effect of a post acute respiratory outreach service for patients with chronic obstructive pulmonary disease on hospital readmission rates.

OBJECTIVE: The aim of this study was to investigate the effect of a Post Acute Respiratory Outreach Service (PAROS) for patients with chronic obstructive pulmonary disease (COPD), on hospital utilization. METHODS: A retrospective cohort of patients was examined, using a nested comparison, to test the hypothesis that PAROS would affect hospital utilization in the 12 months following the intervention. Patients admitted with COPD and subsequently enrolled in PAROS were compared with age, sex and diagnosis-matched controls admitted with COPD, who did not receive PAROS. RESULTS: Of 216 patients admitted with COPD during the 1-year study period, 28 were referred to PAROS. A total of 25 suitable controls were identified. Three cases that could not be matched were excluded from the analysis. There were no significant differences in lung function or prior hospitalization between the two groups at baseline. A significant increase in hospital bed days, in the 12 months following the index admission, was observed in the PAROS group (P = 0.046). There was no difference in the number of admissions or emergency department presentations between the groups. CONCLUSIONS: The PAROS program did not lead to a reduction in hospital utilization. This study supports previous findings that respiratory outreach services delivered immediately post discharge increase hospital utilization.

Aged↗
PubMed2005

Visual field preservation after curative multi-modality treatment of occipital lobe arteriovenous malformations.

OBJECTIVE: Occipital lobe arteriovenous malformations (AVMs) provide challenging management decisions because of their proximity to the visual cortex and optic radiations. Preservation of visual function throughout treatment is the mainstay of therapeutic planning. We reviewed visual field (VF) outcomes of all patients who received curative treatment for occipital AVMs at Stanford University to evaluate the efficacy of different treatment strategies. METHODS: We conducted a retrospective review of 55 patients with occipital AVMs treated at Stanford University between 1984 and 2003. Clinical presentation, AVM morphology, and treatment modality were correlated with VF function before and after therapeutic intervention. RESULTS: Of 55 patients, 48 (87.3%) underwent multimodality AVM treatment (7 patients < 3 yr from radiosurgery were excluded from final analysis). One patient died from intracerebral hemorrhage 11 months post-radiosurgery, and five patients deferred further treatment. Forty-two patients (87.5%) were cured, with no residual AVM on final angiography. Curative therapeutic modalities used included embolization alone (2 patients), microsurgery alone (6 patients), microsurgery with radiosurgery (1 patient), microsurgery with embolization (23 patients), radiosurgery with embolization (4 patients), and embolization with radiosurgery and microsurgery (6 patients). Mean follow-up was 5.8 years including treatment. VF follow-up was available in all 42 patients. Twenty-eight (66.7%) patients experienced no change in VFs, six (14.3%) patients with previously abnormal VFs improved, and eight (19.0%) patients showed worsening of VFs (although none developed a new homonymous VF deficit). Duration of treatment was related to VF outcome in patients who presented without a history of AVM-related hemorrhage. CONCLUSION: Occipital AVMs can be safely cured using multimodality strategies with minimal risk to visual function despite the proximity of these lesions to the visual cortex and associated pathways.

Adolescent↗
PubMed2004

Efficacy and safety of stereotactic radiosurgery for glomus jugulare tumors.

OBJECT: Since the mid-1990s the use of radiosurgery for glomus jugulare tumors has grown in popularity. Despite its increased use, follow-up periods for radiosurgery are short and the numbers of patients reported are small. To add to the available information, the authors report their experience with the application of linear accelerator (LINAC) or CyberKnife modalities in 13 patients with 16 tumors. METHODS: All patients were treated with frame-based LINAC or CyberKnife radiosurgery, with doses ranging from 1400 to 2700 cGy. Patients were retrospectively assessed for posttreatment side effects, which included hearing loss, tongue weakness, and vocal hoarseness. The patients' most recent magnetic resonance (MR) images were also assessed for changes in tumor size. The median follow-up duration was 41 months and the mean follow-up period was 60 months. All tumors remained stable or decreased in size on follow-up MR images. All patients had stable neurological symptoms, and one experienced transient ipsilateral tongue weakness and hearing loss, both of which subsequently resolved. One patient experienced transient ipsilateral vocal cord paresis; however, this individual had received previous external-beam radiation therapy. CONCLUSIONS: The authors' findings continue to support radiosurgery as an effective and safe method of treatment for glomus jugulare tumors that results in low rates of morbidity.

Adult↗