Causal Effect Estimation on Imaging and Clinical Data for Treatment Decision Support of Aneurysmal Subarachnoid Hemorrhage.

Aneurysmal subarachnoid hemorrhage is a serious medical emergency of brain that has high mortality and poor prognosis. Treatment effect estimation is of high clinical significance to support the treatment decision-making for aneurysmal subarachnoid hemorrhage. However, most existing studies on treatment decision support of this disease are unable to simultaneously compare the potential outcomes of different treatments for a patient. Furthermore, these studies fail to harmoniously integrate the imaging data with non-imaging clinical data, both of which are significant in clinical scenarios. In this paper, the key challenges we address are: how to effectively estimate the treatment effect for aneurysmal subarachnoid hemorrhage; and how to utilize multi-modality data to perform this estimation. Specifically, we first propose a novel scheme that uses multi-modality confounders distillation architecture to predict the treatment outcome and treatment assignment simultaneously. Notably, with these distilled confounder features, we design an imaging and non-imaging interaction representation learning strategy to use the complementary information extracted from different modalities to balance the feature distribution of different treatment groups. We have conducted extensive experiments using a clinical dataset of 656 subarachnoid hemorrhage cases, which was collected from the Hospital Authority of Hong Kong. Our method shows consistent improvements on the evaluation metrics of treatment effect estimation, achieving state-of-the-art results over strong competitors. Code is released at https://github.com/med-air/TOP-aSAH.

Reverse Lid Swinging Approach: A Case Series.

In this report, the authors describe the reverse lid swinging approach, which comprises lateral canthotomy, superior lateral cantholysis to free the upper eyelid, and an incision at the superonasal conjunctival fornix for orbital exposure. Four patients underwent orbitotomy using the reverse lid swinging approach for orbital tumor removal (n = 3) or orbital abscess drainage (n = 1). All 4 operations were uneventful, with no optic nerve dysfunction or extraocular dysmotility over the follow-up period. Satisfactory cosmesis was achieved with no visible external scar in all cases. The reverse lid swinging approach provides easy access to medial orbital lesions as demonstrated in the present case series.

Patterns of care and survival of Chinese glioblastoma patients in the temozolomide era: a Hong Kong population-level analysis over a 14-year period.

Background: The aim of this study is to address the paucity of epidemiological data regarding the characteristics, treatment patterns and survival outcomes of Chinese glioblastoma patients. Methods: This was a population-level study of Hong Kong adult (>18 years) Chinese patients with newly diagnosed histologically confirmed glioblastoma between 2006 and 2019. The age standardized incidence rate (ASIR), patient-, tumor- treatment-related characteristics, overall survival (OS) as well as its predictors were determined. Results: One thousand and ten patients with a median follow-up of 10.0 months were reviewed. The ASIR of glioblastoma was 1.0 per 100 000 population with no significant change during the study period. The mean age was 57 + 14 years. The median OS was 10.6 months (IQR: 5.2-18.4). Independent predictors for survival were: Karnofsky performance score >80 (adjusted OR: 0.8; 95% CI: 0.6-0.9), IDH-1 mutant (aOR: 0.7; 95% CI: 0.5-0.9) or MGMT methylated (aOR: 0.7; 95% CI: 0.5-0.8) glioblastomas, gross total resection (aOR: 0.8; 95% CI: 0.5-0.8) and temozolomide chemoradiotherapy (aOR 0.4; 95% CI: 0.3-0.6). Despite the significant increased administration of temozolomide chemoradiotherapy from 39% (127/326) of patients in 2006-2010 to 63% (227/356) in 2015-2019 (P-value < .001), median OS did not improve (2006-2010: 10.3 months vs 2015-2019: 11.8 months) (OR: 1.1; 95% CI: 0.9-1.3). Conclusions: The incidence of glioblastoma in the Chinese general population is low. We charted the development of neuro-oncological care of glioblastoma patients in Hong Kong during the temozolomide era. Although there was an increased adoption of temozolomide chemoradiotherapy, a corresponding improvement in survival was not observed.

A Factorial Analysis on Visual Outcomes of Transsphenoidal Surgery for Pituitary Macroadenoma.

Objective Sellar lesions are possible reversible causes of vision loss. This study is to provide quantitative objective measurement of efficacy of surgery for non-functioning pituitary adenoma and discuss different factors that could affect visual outcome of non-functioning pituitary adenoma. Method This is a single centre, retrospective study conducted at a tertiary neurosurgery referral centre. 108 cases of sellar tumors which underwent surgery during the 3-year period from early June 2015 to late May 2018 were reviewed. Pituitary adenoma that were non-functioning and without apoplexy at initial presentation were selected for the study. We have analyzed the correlation of different factors with the visual outcome, including the extent of vertical decompression in terms of change in tumor height post operation and the extent of lateral decompression in terms of change in Knosp grading. Visual outcome was represented by the visual impairment score (VIS), an integrated measurement of visual acuity and visual field deficit. Results Preoperative absolute tumor height and supracarotid height correlated with preoperative VIS scale ( p ≤ 0.01). Absolute Knosp grading correlates significantly with VA ( p = 0.001) and VF ( p ≤ 0.001) of that particular eye. Although most patients had an objective improvement in visual acuity (VA) (88%) and visual field (VF) (99%) after operation, a larger reduction in tumor height and successful Knosp downgrading after surgery is associated with better VIS improvement. ( p = 0.025) Change in supracarotid height shows trend in correlating with change in VIS ( p = 0.084). Conclusion Height of tumor measured from genu of cavernous ICA correlates better with visual outcome than absolute tumor height. The extent of both vertical and lateral decompression of non-functioning pituitary adenoma are important determinants that lead to better visual outcome. As endoscopic approach is able to achieve a greater degree of lateral decompression, it is a preferred approach in pituitary surgery to achieve a better visual outcome.

Minimally Invasive Tubular Retractor Surgery for Intradural Extramedullary Spinal Tumor Reduces Postoperative Degeneration of Paraspinal Muscle.

Background Minimally invasive surgery (MIS) using a tubular retractor has been increasingly utilized in spinal surgery for degenerative conditions with the benefit of paraspinal muscle preservation. This benefit has not been previously reported for intradural extramedullary tumors using the MIS approach. In this study, we aimed to compare the degree of postoperative fatty degeneration in paraspinal muscle between MIS with tubular retractor (MIS) and open laminectomy (Open) for intradural extramedullary spinal tumors. Methods This was a retrospective review conducted in a tertiary neurosurgical center from 2015 to 2019. The degree of paraspinal muscle fatty degeneration, as measured by Goutallier grade on postoperative magnetic resonance imaging (MRI), was analyzed, and the degree of excision, tumor recurrence rate, and chronic pain were compared between the two surgical approaches. Results Among 9 patients in the MIS group and 33 patients in the Open group, the rate of gross total resection was comparable (MIS: 100.0%, Open: 97.0%, p = 1.000). The degree of paraspinal muscle fatty degeneration was significantly reduced in the MIS group (median Goutallier grade 1 in MIS group vs. median Goutallier grade 2 in Open group, p = 0.023). There was no significant difference in the tumor recurrence rate, complication rate, and chronic pain severity. A consistent trend of reduced analgesic consumption was observed in the MIS group, though not statistically significant. Conclusions Minimally invasive tubular retractor surgery is an effective approach for appropriately selected intradural extramedullary spinal tumors with significantly reduced postoperative fatty degeneration in paraspinal muscle.

Indocyanine Green-Assisted Endoscopic Transorbital Excision of Lateral Orbital Apex Cavernous Hemangioma.

Orbital apex lesions posed operative difficulties to neurosurgeons and ophthalmologists due to limited surgical corridor and close vicinity to cranial nerves and arteries. Lateral orbital apex lesions were traditionally operated via the transcranial route by neurosurgeons. Recently, only a handful of reports have described the use of endoscope alone for excision of lateral orbital apex lesion. Our group, with both endoscopic skull base neurosurgeons and oculoplastic surgeons, has adopted the endoscopic transorbital approach for orbital apex lesions. We also used an indocyanine green (ICG) endoscope to aid identification and dissection of orbital apex cavernous hemangioma, which otherwise can be difficult to differentiate from surrounding intraconal recti muscles. Video 1 captured the first reported case of excision of lateral orbital apex cavernous hemangioma via endoscopic transorbital approach, using a zero-degree ICG endoscope. This was a 64-year-old Chinese woman who presented with right eye painless blurring of vision with visual acuity of 0.6 and right relative afferent pupillary defect. Fundoscopic examination showed absence of right optic disc swelling, and automated visual field testing confirmed a superior and infratemporal visual field defect in the right eye. On magnetic resonance imaging, there was a 1-cm oval mass that was hypointense on T1-weighted and hyperintense on T2-weighted images, with slow enhancement, suggestive of cavernous hemangioma. Optical coherence tomography of the retinal nerve fiber layer showed evidence of subtle right nerve fiber layer thinning. Right endoscopic transorbital excision of the tumor was performed with an ICG-assisted endoscope. Lateral skin crease incision was followed by crescent-shaped superolateral orbital rim removal. Superior and inferior orbital fissures were identified after stripping off the periorbita. The meningoorbital band was divided to release the orbital apex from the middle fossa dura. The greater wing of sphenoid bone was drilled with a 3-mm high-speed diamond burr under irrigation to create space for dissection. Injection of ICG resulted in delayed enhancement of the lesion at around 1 minute and 30 seconds, in contrast to rapid enhancement of surrounding recti muscles at around 30 seconds. Incision of periorbita was guided by ICG enhancement of lesion. The tumor was dissected from the lateral rectus and superior division of oculomotor nerve and was excised en bloc. The supraorbital rim was reconstructed with 2 miniplates. Pathology confirmed the diagnosis of cavernous hemangioma. Postoperatively, the patient had good recovery, with right eye visual acuity of 0.8 and resolution of the relative afferent pupillary defect.

Radiotherapy-induced glioblastoma: distinct differences in overall survival, tumor location, pMGMT methylation and primary tumor epidemiology in Hong Kong chinese patients.

INTRODUCTION: Radiotherapy-induced glioblastomas (RIGB) are a well-known late and rare complication of brain irradiation. Yet the clinical, radiological and molecular characteristics of these tumors are not well characterized. METHODS: This was a retrospective multicentre study that analysed adult patients with newly diagnosed glioblastoma over a 10-year period. Patients with RIGB were identified according to Cahan's criteria for radiation-induced tumors. A case-control analysis was performed to compare known prognostic factors for overall survival (OS) with an independent cohort of IDH-1 wildtype de novo glioblastomas treated with standard temozolomide chemoradiotherapy. Survival analysis was performed by Cox proportional hazards regression. RESULTS: A total of 590 adult patients were diagnosed with glioblastoma. 19 patients (3%) had RIGB. The mean age of patients upon diagnosis was 48 years ± 15. The mean latency duration from radiotherapy to RIGB was 14 years ± 8. The mean total dose was 58Gy ± 10. One-third of patients (37%, 7/19) had nasopharyngeal cancer and a fifth (21%, 4/19) had primary intracranial germinoma. Compared to a cohort of 146 de novo glioblastoma patients, RIGB patients had a shorter median OS of 4.8 months versus 19.2 months (p-value: <.001). Over a third of RIGBs involved the cerebellum (37%, 7/19) and was higher than the control group (4%, 6/146; p-value: <.001). A fifth of RIGBs (21%, 3/19) were pMGMT methylated which was significantly fewer than the control group (49%, 71/146; p-value: .01). For RIGB patients (32%, 6/19) treated with re-irradiation, the one-year survival rate was 67% and only 8% for those without such treatment (p-value: .007). CONCLUSION: The propensity for RIGBs to develop in the cerebellum and to be pMGMT unmethylated may contribute to their poorer prognosis. When possible re-irradiation may offer a survival benefit. Nasopharyngeal cancer and germinomas accounted for the majority of original malignancies reflecting their prevalence among Southern Chinese.

Neurocognitive recovery and global cerebral perfusion improvement after cranioplasty in chronic sinking skin flap syndrome of 18 years: Case report using arterial spin labelling magnetic resonance perfusion imaging.

Sinking skin flap syndrome (SSFS) is a complication among long-term survivors of stroke or traumatic brain injury treated by decompressive craniectomy. The syndrome encompasses a wide spectrum of neurological symptoms including cognitive decline, seizures, speech and sensorimotor deficits. Early cranioplasty appears to improve cerebral perfusion, but the efficacy of cranioplasty in neurocognitive outcome in long-standing SSFS patient is unclear. We report a 64-year-old patient who suffered from traumatic brain injury and underwent decompressive craniectomy 18 years ago. She had chronic SSFS with pre-cranioplasty assessments demonstrating severe neurocognitive impairments which were static over time. After cranioplasty with custom-made polyetheretherketone flap to restore the 264 cm2 skull defect, magnetic resonance perfusion scan with pseudo-continuous arterial spin labelling technique showed a two-fold augmentation of cerebral blood flow in both frontal lobes, as well as areas distal to the sunken skin flap compared to baseline. This is accompanied by improvement of neurocognitive function as assessed by Montreal Cognitive Assessment, Neurobehavioral Cognitive State Examination, and Rivermead Behavioural Memory Test three and six months after cranioplasty. The patient's quality of life and that of her primary carer also showed improvement. This report describes a case of neurocognitive and global cerebral perfusion improvement after cranioplasty in the setting of prolonged SFSS of 18 years, and adds to the growing body of literature supporting the therapeutic role of cranioplasty beyond purely protective or cosmetic indications. The advantages and clinical utility of pCASL MR perfusion in assessing serial CBF before and after cranioplasty is illustrated.

Determining a cut-off residual tumor volume threshold for patients with newly diagnosed glioblastoma treated with temozolomide chemoradiotherapy: A multicenter cohort study.

Standard-of-care treatment of glioblastomas involves maximal safe resection and adjuvant temozolomide chemo-radiotherapy. Although extent of resection (EOR) is a well-known surgical predictor for overall survival most lesions cannot be completely resected. We hypothesize that in the event of incomplete resection, residual tumor volume (RTV) may be a more significant predictor than EOR. This was a multicenter retrospective review of 147 adult glioblastoma patients (mean age 53 years) that underwent standard treatment. Semiautomatic magnetic resonance imaging segmentation was performed for pre- and postoperative scans for volumetric analysis. Cox proportional hazards regression and Kaplan-Meier survival analyses were performed for prognostic factors including: age, Karnofsky performance score (KPS), O(6)-methylguanine methyltransferase (MGMT) promoter methylation status, EOR and RTV. EOR and RTV cut-off values for improved OS were determined and internally validated by receiver operator characteristic (ROC) analysis for 12-month overall survival. Half of the tumors had MGMT promoter methylation (77, 52%). The median tumor volume, EOR and RTV were 43.20 cc, 93.5%, and 3.80 cc respectively. Gross total resection was achieved in 52 patients (35%). Cox proportional hazards regression, ROC and maximum Youden index analyses for RTV and EOR showed that a cut-off value of <3.50 cc (HR 0.69; 95% CI 0.48-0.98) and ≥84% (HR 0.64; 95% CI 0.43-0.96) respectively conferred an overall survival advantage. Independent overall survival predictors were MGMT promoter methylation (adjusted HR 0.35; 95% CI 0.23-0.55) and a RTV of <3.50 cc (adjusted HR 0.53; 95% CI 0.29-0.95), but not EOR for incompletely resected glioblastomas.

A rare cause of sciatica discovered during digital rectal examination: case report of an intrapelvic sciatic notch schwannoma.

Intrapelvic sciatic nerve schwannomas are rare causes for non-discogenic sciatica. We describe a 44-year-old female who had a palpable mass on digital rectal examination that exhibited a positive Tinel's sign. The schwannoma was excised by a posterior transgluteal approach. Patients with negative spinal imaging should undergo pelvic scanning to rule out these tumors.

A Comparative Analysis of the Usefulness of Survival Prediction Models for Patients with Glioblastoma in the Temozolomide Era: The Importance of Methylguanine Methyltransferase Promoter Methylation, Extent of Resection, and Subventricular Zone Location.

OBJECTIVE: Several survival prediction models for patients with glioblastoma have been proposed, but none is widely used. This study aims to identify the predictors of overall survival (OS) and to conduct an independent comparative analysis of 5 prediction models. METHODS: Multi-institutional data from 159 patients with newly diagnosed glioblastoma who received adjuvant temozolomide concomitant chemoradiotherapy (CCRT) were collected. OS was assessed by Cox proportional hazards regression and adjusted for known prognostic factors. An independent CCRT patient cohort was used to externally validate the 1) RTOG (Radiation Therapy Oncology Group) recursive partitioning analysis (RPA) model, 2) Yang RPA model, and 3) Wee RPA model, Chaichana model, and the RTOG nomogram model. The predictive accuracy for each model at 12-month survival was determined by concordance indices. Calibration plots were performed to ascertain model prediction precision. RESULTS: The median OS for patients who received CCRT was 19.0 months compared with 12.7 months for those who did not (P < 0.001). Independent predictors were: 1) subventricular zone II tumors (hazard ratio [HR], 1.6; 95% confidence interval [CI], 1.0-2.5); 2) methylguanine methyltransferase promoter methylation (HR, 0.36; 95% CI, 0.2-0.6); and 3) extent of resection of >85% (HR, 0.59; 95% CI, 0.4-0.9). For 12-month OS prediction, the RTOG nomogram model was superior to the RPA models with a c-index of 0.70. Calibration plots for 12-month survival showed that none of the models was precise, but the RTOG nomogram performed relatively better. CONCLUSIONS: The RTOG nomogram best predicted 12-month OS. Methylguanine methyltransferase promoter methylation status, subventricular zone tumor location, and volumetric extent of resection should be considered when constructing prediction models.

Use of subdural drain for chronic subdural haematoma? A 4-year multi-centre observational study of 302 cases.

Chronic subdural haematoma (CSDH) is a common neurosurgical condition and is more prevalent in the ageing population. Studies have suggested that placement of subdural drains after burr-hole drainage was associated with lower recurrence rates. However, a considerable proportion of surgeons remained unconvinced of the effectiveness of drain placement and concerns exist with the potential complications this additional manoeuvre entails such as infection or bleeding. The aim of the present study is to evaluate the impact of subdural drain on CSDH recurrence and its safety. This is a multicentre observational study. Data of consecutive patients with burr-hole drainage performed for CSDH in three hospitals in Hong Kong during a four-year period from January 2008 to December 2011 were prospectively collected and retrospectively analysed. The primary outcome was symptomatic recurrence requiring re-operation. Secondary outcomes included the modified Rankin scales (mRS), morbidity and mortality at six months. A total of 302 patients were identified. The recurrence rate was 8.72% (13/149) with drain placement versus 16.3% (25/153) with no drain (Odds Ratio=0.489, 95%CI 0.240-0.998; p=0.0463). Local wound infection, subdural empyema, acute subdural haematoma and other complications had no significant difference. Six-month mRS, 30-day mortality and six-month mortality were comparable in both groups. In conclusion, the use of subdural drain significantly reduced recurrence with no significant increase in complications.

Intra-arterial revascularization therapy for basilar artery occlusion-a systematic review and analysis.

Acute basilar artery occlusion has been managed aggressively with various modalities due to its potentially debilitating outcome. While intra-arterial mechanical thrombectomy with stentriever has established clear evidence for anterior circulation stroke with large vessel occlusion as an adjunct to intravenous thrombolysis or the sole modality in intravenous thrombolysis ineligible patients, similar high-level evidence was not available for intra-arterial mechanical thrombectomy of posterior circulation stroke with acute basilar artery occlusion. We hence perform a systematic review of current literature to compare intra-arterial pharmacological thrombolysis (IA-P) and intra-arterial mechanical thrombectomy (IA-MT) for acute basilar artery occlusion. Forty-one studies published between 1996 and 2015 were compared and studied by odds ratio analysis using Mantel-Haenszel risk ratio estimation, and time trend analysis using meta-regression. Patients in the IA-MT group were older, presented with more severe stroke, and more likely received treatment more than 12 h since onset of stroke. At 3 months, survival and clinical outcome were superior in the IA-MT group than the IA-P group, associated with higher recanalization rate. There were no difference between proportion of dependent survivors, and rate of symptomatic intracerebral hemorrhage across groups. Intra-arterial thrombolysis with mechanical devices led to improved survival, better short-term clinical outcome and higher recanalization rate than intra-arterial pharmacological thrombolysis.

Use of the pipeline embolization device to treat recently ruptured dissecting cerebral aneurysms.

The Pipeline embolization device (PED) is one of the flow-diverting stents approved for the treatment of unruptured large or wide-necked cerebral aneurysms in 2011(1). Its use has now been extended to the treatment of recently ruptured dissecting cerebral aneurysm, carotid pseudoaneurysm from radiation injury, and blister aneurysms(2,3). We aimed to evaluate the effectiveness of utilizing the PED as a primary treatment for ruptured dissecting intracranial aneurysms. A single center retrospective review was conducted for all patients primarily treated with PED for acute subarachnoid hemorrhage (SAH) from ruptured dissecting cerebral aneurysms between December 2010 and February 2013. Patients were followed up with CT angiogram (CTA) or digital subtraction angiogram (DSA). Eight patients with a total of eight dissecting aneurysms were identified. The mean duration from SAH to treatment was 2.5 days. Six of the aneurysms arose from vertebral arteries and two from the basilar artery. Immediate check-DSA confirmed satisfactory contrast stasis in all eight cases, and complete aneurysmal obliteration was achieved at six months. There were two (25%) procedure-related complications, but no major procedure-related complications, such as thromboembolic events or rebleeding from aneurysm were encountered. The PED is a feasible treatment option for ruptured dissecting cerebral aneurysms in acute phase. According to our experience, using PED as flow-diverters in acute SAH does not significantly increase the complication risks or mortality rate if the antiplatelet regime is carefully monitored. Future studies shall evaluate the optimal antiplatelet regimen for using the PED in the acute phase.

Review and recommendations on management of refractory raised intracranial pressure in aneurysmal subarachnoid hemorrhage.

Intracranial hypertension is commonly encountered in poor-grade aneurysmal subarachnoid hemorrhage patients. Refractory raised intracranial pressure is associated with poor prognosis. The management of raised intracranial pressure is commonly referenced to experiences in traumatic brain injury. However, pathophysiologically, aneurysmal subarachnoid hemorrhage is different from traumatic brain injury. Currently, there is a paucity of consensus on the management of refractory raised intracranial pressure in spontaneous subarachnoid hemorrhage. We discuss in this paper the role of hyperosmolar agents, hypothermia, barbiturates, and decompressive craniectomy in managing raised intracranial pressure refractory to first-line treatment, in which preliminary data supported the use of hypertonic saline and secondary decompressive craniectomy. Future clinical trials should be carried out to delineate better their roles in management of raised intracranial pressure in aneurysmal subarachnoid hemorrhage patients.

Endovascular treatment of ruptured internal carotid artery pseudoaneurysms after irradiation for nasopharyngeal carcinoma patients.

OBJECTIVES. To evaluate the efficacy and complications of endovascular treatment for ruptured internal carotid artery pseudoaneurysms following irradiation of nasopharyngeal carcinoma. DESIGN. Retrospective case series. SETTING. Tertiary neurosurgical referral unit of a Hong Kong public hospital. PATIENTS. Patients with ruptured radiation-induced internal carotid artery pseudoaneurysms that were treated endovascularly from October 1999 to October 2011 at Queen Elizabeth Hospital were reviewed. Hospital records, imaging, and angiographic data were studied. RESULTS. During the study period, 15 such nasopharyngeal carcinoma patients were treated by endovascular means at Queen Elizabeth Hospital. Ten presented with epistaxis, three with otorrhagia (bleeding from the ear), and two with both. Therapeutic occlusion of the affected internal carotid artery was performed in four patients, and stenting of the artery (with or without coil obliteration of the pseudoaneurysm) was performed in 11. Immediate haemostasis was achieved in all cases. One (7%) of the 15 patients endured symptomatic recurrence of the pseudoaneurysm, and in another an asymptomatic residual pseudoaneurysm was noted in the follow-up angiogram. Three patients suffered clinically significant procedure-related complications, including cerebral infarction (n=2) and brain abscess (n=1). In the angiograms obtained after a mean post-treatment interval of 13 (range, 0.7-60) months, the stent patency rate was 67%. All three patients with occluded stents were asymptomatic. CONCLUSIONS. Ruptured internal carotid artery pseudoaneurysms following radiotherapy is a rare but life-threatening condition. Endovascular treatment by occlusion or reconstruction of the internal carotid artery with stents provides immediate haemostasis and obliteration of the pseudoaneurysms, with a low recurrence rate. Long-term follow-up is necessary to look out for delayed post-treatment complications.

Traumatic Brain Injury in the Elderly: Is it as Bad as we Think?

Traumatic brain injury in elderly patients is a neglected global disease burden. The main cause is fall, followed by motor vehicle accidents. This review article summarizes different aspects of geriatric traumatic brain injury, including epidemiology, pathology, and effects of comorbidities and pre-injury medications such as antiplatelets and anticoagulants. Functional outcome with or without surgical intervention, cognitive outcome, and psychiatric complications are discussed. Animal models are also reviewed in attempt to explain the relationship of aging and outcome, together with advances in stem cell research. Though elderly people in general did fare worse after traumatic brain injury, certain "younger elderly" people, aged 65-75 years, could have a comparable outcome to younger adults after minor to moderate head injury.

The use of diffusion tensor tractography to measure the distance between the anterior tip of the Meyer loop and the temporal pole in a cohort from Southern China.

OBJECT: Anterior temporal lobe resection plus amygdalohippocampectomy can cause damage to the anterior portion of the optic radiation, also known as the Meyer loop, resulting in homonymous superior quadrantanopia. Magnetic resonance diffusion tensor tractography (DTT) of the Meyer loop can help in surgical planning. In this study, the distance of the anterior tip of the Meyer loop to the temporal lobe pole (ML-TP) in the Southern Chinese population was assessed. METHODS: The authors studied 16 Southern Chinese individuals (8 men and 8 women; mean age 45.6 years, range 21-60 years). Diffusion tensor images were obtained with a 3-T MR imaging system using a single-shot spin echo echo planar imaging sequence. Two trained operators, one neurosurgeon (Operator A) and one radiologist (Operator B), carried out the DTT analysis with software iPlan (BrainLAB) and FiberTrak (Philips). RESULTS: For the 32 temporal lobes, the intraclass correlation coefficient (ICC) of the 2 operators' results using iPlan was 0.96, while that of Operator A using iPlan and Operator B using FiberTrak was 0.75. The ICC of Operator B using iPlan and FiberTrak was 0.81. The ML-TP distance of normal lobes (30 lobes [2 lobes that previously underwent surgery were excluded]) was 36.3±5.5 mm (range 26.6-48.9 mm), 36.3±5.3 mm (range 26.8-48.2 mm), and 35.9±6.4 mm (range 20.8-48.4 mm) for Operator A using iPlan, Operator B using iPlan, and Operator B using FiberTrak, respectively (p>0.05). CONCLUSIONS: The 2 operators reached good agreement on ML-TP distance measurement using DTT. The DDT results can be more software dependent than operator dependent. The measurement with FiberTrak demonstrated larger range and standard deviation than measurement with iPlan.