Historical and future trends in emergency pituitary referrals: a machine learning analysis.

PURPOSE: Acute pituitary referrals to neurosurgical services frequently necessitate emergency care. Yet, a detailed characterisation of pituitary emergency referral patterns, including how they may change prospectively is lacking. This study aims to evaluate historical and current pituitary referral patterns and utilise state-of-the-art machine learning tools to predict future service use. METHODS: A data-driven analysis was performed using all available electronic neurosurgical referrals (2014-2021) to the busiest U.K. pituitary centre. Pituitary referrals were characterised and volumes were predicted using an auto-regressive moving average model with a preceding seasonal and trend decomposition using Loess step (STL-ARIMA), compared against a Convolutional Neural Network-Long Short-Term Memory (CNN-LSTM) algorithm, Prophet and two standard baseline forecasting models. Median absolute, and median percentage error scoring metrics with cross-validation were employed to evaluate algorithm performance. RESULTS: 462 of 36,224 emergency referrals were included (referring centres = 48; mean patient age = 56.7 years, female:male = 0.49:0.51). Emergency medicine and endocrinology accounted for the majority of referrals (67%). The most common presentations were headache (47%) and visual field deficits (32%). Lesions mainly comprised tumours or haemorrhage (85%) and involved the pituitary gland or fossa (70%). The STL-ARIMA pipeline outperformed CNN-LSTM, Prophet and baseline algorithms across scoring metrics, with standard accuracy being achieved for yearly predictions. Referral volumes significantly increased from the start of data collection with future projected increases (p < 0.001) and did not significantly reduce during the COVID-19 pandemic. CONCLUSION: This work is the first to employ large-scale data and machine learning to describe and predict acute pituitary referral volumes, estimate future service demands, explore the impact of system stressors (e.g. COVID pandemic), and highlight areas for service improvement.

IgG4-related hypophysitis: a retrospective cohort study.

PURPOSE: IgG4-related hypophysitis (IgG4-RH) is a rare chronic inflammatory condition of the pituitary gland. This study reports the presentation, management and outcomes for patients with histologically proven IgG4-related hypophysitis. METHODS: A prospectively maintained electronic database was searched over a 14-year period from 1 January 2007 to 31 December 2020 at a single academic centre to identify all patients with a histological diagnosis of IgG4-RH. A retrospective case note review from electronic health records was conducted for each case to extract data on their presentation, management and outcomes. RESULTS: A total of 8 patients (5 male) with a median age of 51 years were identified. The most common presenting symptoms were headache (4/8; 50%), fatigue (3/8; 37.5%) and visual impairment (2/8; 25%). Three patients were initially treated with high-dose steroids aiming for reduction of the pituitary mass. However, ultimately all patients underwent transsphenoidal surgery. Post-operative changes included radiological reduction in pituitary mass in all patients that had imaging (7/7; 100%), improvement in vision (1/2; 50%), residual thick pituitary stalk (5/7; 71.4%), persistent anterior hypopituitarism (4/8; 50%) and panhypopopituitarism including diabetes insipidus (3/8; 37.5%). CONCLUSIONS: IgG4-RH is an increasingly recognised entity presenting with a variety of symptoms and signs. Clinical presentation is similar to other forms of hypophysitis. It is therefore important to consider IgG4-RH as a differential and to have a low threshold for pituitary biopsy, the diagnostic gold standard. The diagnosis of IgG4-RH will guide decisions for additional workup for IgG4-related disease, multi-disciplinary team involvement and follow-up.

Intra-operative recurrent laryngeal nerve stimulation during anterior cervical discectomy: a simple and effective technique.

Recurrent laryngeal nerve (RLN) palsy is a recognised complication of anterior cervical discectomy (ACD) surgery. We report our experience of intra-operative neuromonitoring using RLN stimulation in 19 patients undergoing ACD surgery. This simple and safe technique has the potential to reduce the incidence of RLN palsy in this patient group.

Clinical validation of true frameless stereotactic biopsy: analysis of the first 125 consecutive cases.

OBJECTIVE: A lockable guide device, adjustable for positioning, was used to obtain samples for tissue analysis during brain biopsy procedures performed using an interactive image guidance system. Clinical validation of this technique, which was developed for true frameless stereotactic biopsies, and analyses of the histological yield, complication rate, and patient demographic characteristics for a large series of frameless stereotactic biopsies were the purposes of this study. METHODS: Demographic, radiological, surgical, and clinical data were prospectively collected for a series of 125 frameless stereotactic biopsies performed using the technique described in detail previously. RESULTS: Eighty-six procedures were magnetic resonance imaging-directed and 39 were computed tomography-directed. The mean diameter of the biopsied lesions was 36 mm, and the mean distance from the skin was 35.8 mm. Sixteen percent of the patients harbored multiple lesions, and 5.6% of the biopsied lesions were infratentorial. The mean operative time (including the entire anesthetic time) was 1.5 hours. The smear examination findings were corroborated by conclusive histological results in 96% of the cases, and definitive positive diagnoses were obtained in 122 cases (97.6%). Ten patients experienced surgical complications, but the sustained morbidity rate was 2.4% (including the death of a patient who was in critical clinical condition preoperatively and who died 2 mo later as a result of a chest infection; mortality rate, 0.8%). CONCLUSION: This true frameless stereotactic biopsy technique was associated with low morbidity and mortality rates and an excellent diagnostic yield, with overall results at least as good as those observed for frame-based stereotaxy. The excellent accuracy results demonstrated previously and statistically significant reductions in operative time, as well as improved image presentation, target selection, and simplicity, support the use of this frameless stereotactic technique in preference to frame-based biopsy techniques.

Precise cannulation of the foramen ovale in trigeminal neuralgia complicating osteogenesis imperfecta with basilar invagination: technical case report.

OBJECTIVE AND IMPORTANCE: Trigeminal neuralgia is a rare feature of basilar invagination, which is itself a complication of osteochondrodysplastic disorders. Microvascular decompression is an unattractive option in medically refractory cases. The conventional percutaneous approach to the trigeminal ganglion is anatomically impossible because the foramen ovale points inferiorly and posteromedially. We report a new technique for image-guided trigeminal injection in a patient with basilar invagination complicating osteogenesis imperfecta. CLINICAL PRESENTATION: A 26-year-old woman with osteogenesis imperfecta presented with a 3-year history of typical left maxillary division trigeminal neuralgia, which was poorly controlled by carbamazepine at the maximum tolerated dose. She had obvious cranial deformities, left optic atrophy, delayed left eye closure, tongue atrophy, but normal facial sensation and corneal reflexes. A computed tomographic scan and magnetic resonance imaging confirmed severe basilar invagination. TECHNIQUE: Frameless stereotactic glycerol injection of the left trigeminal ganglion was performed under general anesthesia using the infrared-based EasyGuide Neuro system (Philips Medical Systems, Best, The Netherlands) with magnetic resonance imaging and computed tomographic registration. The displaced and distorted left foramen ovale was cannulated via a true frameless stereotactic method with the trajectory determined by virtual pointer elongation. The needle placement was confirmed with injection of contrast medium into the trigeminal cistern. The path needed to enter the foramen traversed the right cheek, soft palate, and left tonsil. The patient went home pain-free with a preserved corneal reflex and no complications. CONCLUSION: Frameless stereotaxy allows customization to individual patient anatomy and may be adapted to a variety of percutaneous procedures used in areas where the anatomy is complex.

'Correctable undetected visual acuity deficit' in patients aged 65 and over attending an accident and emergency department.

The rate of occurrence of correctable undetected visual acuity deficit (CUVAD) in a population of patients aged 65 and over was investigated, using a pinhole screening method, to compare the sociodemographic and optical eye care habits of patients with or without a functionally significant CUVAD. Of 136 patients 46 (34%) were found to have a functionally significant CUVAD in one or both eyes which was not significantly associated with optician or general practitioner contact, age, sex, social class, living situation, or number of medications. Half the patients with significant CUVAD had not attended for 2 years mainly because of financial considerations. Three quarters attended of their own volition; only one in seven were prompted by opticians' postal invitations. It was concluded that a significant degree of CUVAD could be detected using a simple procedure which can be carried out by general practitioners as part of their general elderly health screen.

Accuracy of true frameless stereotaxy: in vivo measurement and laboratory phantom studies. Technical note.

The authors present the results of accuracy measurements, obtained in both laboratory phantom studies and an in vivo assessment, for a technique of frameless stereotaxy. An instrument holder was developed to facilitate stereotactic guidance and enable introduction of frameless methods to traditional frame-based procedures. The accuracy of frameless stereotaxy was assessed for images acquired using 0.5-tesla or 1.5-tesla magnetic resonance (MR) imaging or 2-mm axial, 3-mm axial, or 3-mm helical computerized tomography (CT) scanning. A clinical series is reported in which biopsy samples were obtained using a frameless stereotactic procedure, and the accuracy of these procedures was assessed using postoperative MR images and image fusion. The overall mean error of phantom frameless stereotaxy was found to be 1.3 mm (standard deviation [SD] 0.6 mm). The mean error for CT-directed frameless stereotaxy was 1.1 mm (SD 0.5 mm) and that for MR image-directed procedures was 1.4 mm (SD 0.7 mm). The CT-guided frameless stereotaxy was significantly more accurate than MR image-directed stereotaxy (p = 0.0001). In addition, 2-mm axial CT-guided stereotaxy was significantly more accurate than 3-mm axial CT-guided stereotaxy (p = 0.025). In the clinical series of 21 frameless stereotactically obtained biopsies, all specimens yielded the appropriate diagnosis and no complications ensued. Early postoperative MR images were obtained in 16 of these cases and displacement of the biopsy site from the intraoperative target was determined by fusion of pre- and postoperative image data sets. The mean in vivo linear error of frameless stereotactic biopsy sampling was 2.3 mm (SD 1.9 mm). The mean in vivo Euclidean error was 4.8 mm (SD 2 mm). The implications of these accuracy measurements and of error in stereotaxy are discussed.

Postimaging brain distortion: magnitude, correlates, and impact on neuronavigation.

OBJECT: This prospective study was conducted to quantify brain shifts during open cranial surgery, to determine correlations between these shifts and image characteristics, and to assess the impact of postimaging brain distortion on neuronavigation. METHODS: During 48 operations, movements of the cortex on opening, the deep tumor margin, and the cortex at completion were measured relative to the preoperative image position with the aid of an image-guidance system. Bone surface offset was used to assess system accuracy and correct for registration errors. Preoperative images were examined for the presence of edema and to determine tumor volume, midline shift, and depth of the lesion below the skin surface. Results were analyzed for all cases together and separately for four tumor groups: 13 meningiomas, 18 gliomas, 11 nonglial intraaxial lesions, and six skull base lesions. For all 48 cases the mean shift of the cortex after dural opening was 4.6 mm, shift of the deep tumor margin was 5.1 mm, and shift of the cortex at completion was 6.7 mm. Each tumor group displayed unique patterns of shift, with significantly greater shift at depth in meningiomas than gliomas (p = 0.007) and significantly less shift in skull base cases than other groups (p = 0.003). Whereas the preoperative image characteristics correlating with shift of the cortex on opening were the presence of edema and depth of the tumor below skin surface, predictors of shift at depth were the presence of edema, the lesion volume, midline shift, and magnitude of shift of the cortex on opening. CONCLUSIONS: This study quantified intraoperative brain distortion, determined the different behavior of tumors in four pathological groups, and identified preoperative predictors of shift with which the reliability of neuronavigation may be estimated.

The EASI project--improving the effectiveness and quality of image-guided surgery.

In recent years, advances in computer technology and a significant increase in the accuracy of medical imaging have made it possible to develop systems that can assist the clinician in diagnosis, planning, and treatment. This paper deals with an area that is generally referred to as computer-assisted surgery, image-directed surgery, or image-guided surgery. We report the research, development, and clinical validation performed since January 1996 in the European Applications in Surgical Interventions (EASI) project, which is funded by the European Commission in their "4th Framework Telematics Applications for Health" program. The goal of this project is the improvement of the effectiveness and quality of image-guided neurosurgery of the brain and image-guided vascular surgery of abdominal aortic aneurysms, while at the same time reducing patient risks and overall cost. We have developed advanced prototype systems for preoperative surgical planning and intraoperative surgical navigation, and we have extensively clinically validated these systems. The prototype systems and the clinical validation results are described in this paper.

Clinical introduction of an adjustable rigid instrument holder for frameless stereotactic interventions.

Interactive image guidance is now in routine use for open neurosurgical procedures and has demonstrated patient benefits. However, freehand interactive guidance is not an appropriate replacement for the traditional frame-based stereotactic procedures of biopsy, electrode placement, and functional lesioning. These point-based procedures require precise target localization and direct instrument guidance to avoid collateral brain injury. To perform true frameless stereotactic procedures requires a guide that is also adjustable for positioning, lockable, and adaptable to multiple instruments. We describe such a device, which is employed for the guidance of biopsy needles, shunts, electrodes, and endoscopes during neuronavigation. The method of frameless stereotactic biopsy retrieval with an infrared-based neuronavigation system is described, clinical results are given, and further areas of application discussed.

Spinal epidural hematoma caused by pseudogout: a case report and literature review.

Study Design Case report. Objective We present the first reported case of spontaneous spinal epidural hematoma secondary to calcium pyrophosphate crystal deposition disease (pseudogout) in a 75-year-old woman. Methods A retrospective review of the patient's case notes was undertaken and the limited literature on this subject reviewed. Results This patient presented with sudden-onset lower limb paresis, sensory loss, urinary retention, and back pain. Magnetic resonance imaging showed an epidural hematoma, which was evacuated. Histologic specimens of the clot showed calcium pyrophosphate dihydrate crystal deposits (pseudogout). Conclusion The importance of histopathologic review of surgical specimens is highlighted when considering the differential diagnosis of apparently spontaneous spinal epidural hematoma.

Disintegration of cervical intervertebral BOP grafts with neurological sequelae: a report of two cases.

We report the case histories of two patients treated in our unit for cervical radiculopathy by anterior cervical discectomy and BOP grafting. Both grafts disintegrated within 6 weeks of insertion resulting in increased neurological deficit from cervical cord compression. At reoperation fibres from the grafts were found to have separated and the larger fragments had extruded into the vertebral canal. No evidence of infection was seen, but a foreign body reaction was found in one case. Following graft removal the patients improved symptomatically although one was left with permanent mild biceps weakness.

Epidermal growth factor receptor activity and clinical outcome in glioblastoma and meningioma.

Epidermal growth factor receptor (EGF-r) activity in patients with glioblastoma multiforme (GBM: n = 27) and meningioma (n = 18) was compared with clinical outcome. All patients with GBM were followed up to time of death. In patients with GBM there was no significant relationship between EGF-r activity and either patient survival time or age. EGF-r activity in patients with meningioma was neither related to age nor, at a median of 40 months after surgery, to clinical outcome. These results suggest that routine estimation of EGF-r activity in these intracranial tumours is not indicated.

Extended anterior cervical discectomy without fusion: a simple and sufficient operation for most cases of cervical degenerative disease.

Of 291 operations performed for cervical degenerative disease causing cord or root involvement over a 12-year period 187 have been treated by extended anterior discectomy without fusion, removing bone on either side of the posterior disc space so as to give a wide exposure of the anterior spinal and root dura. The technique has been used for 73% of the cases operated on in the last four years. Nine patients (4.8%) required an additional posterior decompression for coexisting spinal or root canal stenosis. By the first postoperative follow-up at 2-4 months 94.5% of patients showed clear neurological or functional improvement, 3% were worse and 1.5% had died (the deaths were in elderly patients with severe myelopathy and intercurrent disease). Minor treatable complications occurred in 3.2%. Only two patients (1%) complained of persistent postoperative neck pain. Patients were mobilized immediately after surgery without a collar and most left hospital within 1-4 days. A single level decompression was sufficient in 92% of patients and only one patient required more than two levels to be decompressed. In 79% of cases soft disc protrusions contributed to the compression while in 21% osteophytes alone caused the compression. We believe that this simple technique is a sufficient surgical treatment for the majority of cases of cervical degenerative disease. It does not require a fusion and avoids the specific problems and complications associated with Cloward type operations. We are engaged at present in a long-term follow up study of these patients, but to date no late problems have become apparent.

The hitch stitch: an obsolete neurosurgical technique?

The objective was to assess the efficacy of dural tenting sutures as a prophylactic measure against extradural haemorrhage following craniotomy. A comparison was made of postoperative extradural haemorrhage between a surgeon always using tenting sutures and a surgeon who never uses them. The subjects consisted of 130 adult patients, 44 with postoperative scans, with normal blood coagulation who underwent elective supratentorial craniotomy (September 1998 to December 2000). Outcome measures were haematoma volume and midline shift as measured on CT and reoperation due to extradural haematoma. The group using tenting sutures had larger median extradural haematoma (2.5 vs 2.0 ml) and midline shift (3 vs 0 mm) than the omitting group. These differences were not significant (P = 0.74 and 0.84). Reoperation due to extradural haemorrhage occurred in 3.6% of the group using tenting sutures and in 0% of the group omitting them. Prophylactic dural tenting sutures do not reduce the size of extradural haematomas in this study. A prospective, randomized trial is needed to eliminate surgeon bias.

A technique to reduce CSF leakage after acoustic neuroma surgery.

Leakage of CSF remains a frequent complication of acoustic neuroma surgery in contrast with the significant reductions achieved in mortality and morbidity. The rate of CSF leakage following acoustic neuroma excision is presented for 49 consecutive patients. The first 23 operations were performed before the introduction of a new technique for sealing off air cells in the internal auditory meatus and the following 26 with this new method. CSF leakage occurred in nine of the first 23 patients compared with one of 26 patients using this method (p < 0.01). The two groups were similar for tumour size and facial nerve preservation rate. The technique, which avoids the need for a second donor site wound or continuous lumbar drainage, is described and factors leading to CSF leakage are discussed.

Neuronavigation--impact on operating time.

It is uncertain whether the use of image-guided surgery has an influence on operating time. We prospectively studied the time requirements which have to be invested for using image-guided surgery and performed a comparison of operating room times from 125 matched pairs of image-guided and conventional operations. Our study revealed that neuronavigation has to be regarded as time neutral in general neurosurgery, whereas in stereotactic surgery, namely biopsy retrival, a significant reduction of anaesthetic time can be achieved through the complete separation of imaging and operation in the frameless approach.

The advantages of frameless stereotactic biopsy over frame-based biopsy.

A comparison study is presented, which examines the outcome, complications and cost of stereotactic brain biopsy performed with a frameless versus a frame-based method. The technique of frameless stereotactic biopsy has been shown previously, in both laboratory and in vivo studies, to achieve a level of accuracy at least equal to frame-based biopsy. The investigators have validated the technique in a large clinical series. The frameless and frame-based series were concurrent, comprising 76 and 79 cases, respectively. The frameless stereotactic technique involved standard needle biopsy, targeted by an image-guidance system and directed by a novel rigid adjustable instrument-holder. Frame-based biopsies were performed with the CRW and Leksell systems. There were no significant differences in the demographics, lesion site, size and pathologies between the groups. Operating theatre occupancy and anaesthetic time were both significantly shorter for the frameless series than the frame-based series (p < 0.0001). In addition, the complication rate in the frameless biopsy series was significantly lower than in the frame-based series (p = 0.018). This resulted in lower ITU bed occupancy (p = 0.02), shorter mean hospital stay (p = 0.0013) and significant cost savings (p = 0.0022) for the frameless stereotactic biopsy group, despite the greater use of more expensive MRI in these cases. This comparison study demonstrates that the superior imaging, target visualization and flexibility of the technique of frameless stereotactic biopsy translates into tangible advantages for safety, time and cost when compared with the current gold-standard of frame-based biopsy. The principles are discussed and the authors propose a definition for the term 'frameless stereotaxy'.

Interactive image-guided neuroendoscopy: development and early clinical experience.

Technical advances and pioneering surgeons have established neuroendoscopy as an accepted diagnostic and therapeutic tool. The clinical indications for endoscopy, variety of operative techniques and number of endoscopic surgeons continue to increase steadily. However, there are fundamental limits to the scope of freehand endoscopy principally governed by the need for direct vision of anatomical and pathological structures. In addition, whilst the expert neuroendoscopist is only occasionally disorientated by complex distorted anatomy, the rising number of novices are likely to be mislead relatively often. We report the integration of neuroendoscopy with an optical neuronavigation system to provide interactive image-guided neuroendoscopy. This combination both removes the constraining requirement for direct vision and provides accurate localisation to guide the surgeon during surgery. We describe the clinical application of this method to two cases where image-guided endoscopy was essential to the safe completion of the procedure.