Ari G. Chacko

Intraoperative ultrasound in determining the extent of resection of parenchymal brain tumours--a comparative study with computed tomography and histopathology.

Summary¶Background. Radical excision of parenchymal brain tumours is generally associated with a better long-term outcome; however, it is difficult to ascertain the extent of resection at surgery. We used intra-operative ultrasound [IOUS] to help detect residual tumour and define the tumour-brain interface.Methods. Thirty-five patients with parenchymal brain lesions including 11 low-grade and 22 high-grade tumours and 2 inflammatory granulomata were included in the study. The IOUS was used to localize tumours not seen on the surface, define their margins and assess the extent of resection at the end of surgery. Multiple samples from the tumour-brain interface which were reported as tumour or normal tissue on IOUS were submitted to histopathology. The IOUS findings were compared with a postoperative contrast enhanced computed tomogram [CT] and with histopathology.Results. All tumours irrespective of histology were hyperechoic on IOUS. IOUS was useful in localizing those tumours not seen on the surface of the brain. In 71.4% of cases IOUS was useful in defining their margins, however in the remaining cases the margins were ill-defined. The tumour margins were ill-defined in those treated previously by radiation. With regard to the extent of excision, after excluding the cases who were irradiated, it was found that in the 28 patients who had parenchymal neoplasms, there was concordance between the ultrasound findings and the postoperative CT scan in 23 cases. Of the 79 samples taken from the tumor-brain interface which were reported as tumour on ultrasound, 66 had histopathological evidence of tumour while 13 samples were negative for tumour. On the other hand, in the tissue sent from 17 sites where the IOUS showed no residual tumour, 2 were positive for tumour on histopathology while 15 were negative.Interpretation. In conclusion, IOUS is a cheap and useful real-time tool for localizing tumours not seen on the brain surface, for defining their margins and for determining the extent of resection.

Atypical teratoid/rhabdoid tumor arising in the setting of a pleomorphic xanthoastrocytoma.

We present a case of a 23-year-old man with a tumor containing glial and rhabdoid elements where the former had features of a pleomorphic xanthoastrocytoma (PXA) and the latter had the immunophenotype and genetic profile of an atypical rhabdoid/teratoid tumor. The patient presented with a short history of raised intracranial pressure with rapid deterioration in sensorium. He had a poor outcome despite surgery and radiotherapy. We report this case because of its unusual presentation in adulthood and its occurrence in association with a PXA. We speculate that the PXA was a quiescent tumor and that the secondary genetic alterations, including inactivation of the INI1 gene led to clinical progression.

Awake craniotomy and electrophysiological mapping for eloquent area tumours

OBJECTIVE An awake craniotomy facilitates radical excision of eloquent area gliomas and ensures neural integrity during the excision. The study describes our experience with 67 consecutive awake craniotomies for the excision of such tumours. METHODS Sixty-seven patients with gliomas in or adjacent to eloquent areas were included in this study. The patient was awake during the procedure and intraoperative cortical and white matter stimulation was performed to safely maximize the extent of surgical resection. RESULTS Of the 883 patients who underwent craniotomies for supratentorial intraaxial tumours during the study period, 84 were chosen for an awake craniotomy. Sixty-seven with a histological diagnosis of glioma were included in this study. There were 55 men and 12 women with a median age of 34.6 years. Forty-two (62.6%) patients had positive localization on cortical stimulation. In 6 (8.9%) patients white matter stimulation was positive, five of whom had responses at the end of a radical excision. In 3 patients who developed a neurological deficit during tumour removal, white matter stimulation was negative and cessation of the surgery did not result in neurological improvement. Sixteen patients (24.6%) had intraoperative neurological deficits at the time of wound closure, 9 (13.4%) of whom had persistent mild neurological deficits at discharge, while the remaining 7 improved to normal. At a mean follow-up of 40.8 months, only 4 (5.9%) of these 9 patients had persistent neurological deficits. CONCLUSION Awake craniotomy for excision of eloquent area gliomas enable accurate mapping of motor and language areas as well as continuous neurological monitoring during tumour removal. Furthermore, positive responses on white matter stimulation indicate close proximity of eloquent cortex and projection fibres. This should alert the surgeon to the possibility of postoperative deficits to change the surgical strategy. Thus the surgeon can resect tumour safely, with the knowledge that he has not damaged neurological function up to that point in time thus maximizing the tumour resection and minimizing neurological deficits.

Value of visual evoked potential monitoring during trans-sphenoidal pituitary surgery

The visual outcome of 22 patients undergoing trans-sphenoidal excision of pituitary macroadenomas with intraoperative flash visual evoked potential (VEP) monitoring (Group A), was compared with a non-randomized group of 14 patients who had undergone similar operations without VEP monitoring (Group B). Tumour size, preoperative visual acuity, peripheral fields, and latencies and amplitudes of P1 and P2 were analysed to ascertain the best predictor of postoperative visual function. It was found that patients in Group A had a significantly greater improvement in field defects than those in Group B. There was no difference in postoperative improvement in visual acuity between the two groups. None of the variables analysed were good predictors of visual outcome.

The transpedicular approach in the management of thoracic spine tuberculosis: a short-term follow up study.

Study Design. A retrospective descriptive assessment of the clinical and radiologic outcomes of 11 patients who underwent transpedicular decompression for thoracic spine tuberculosis. Objectives. To study the neurologic and radiologic outcomes in patients who underwent transpedicular decompression for thoracic spine tuberculosis. Summary of Background Data. Several approaches have been used in the management of thoracic spine tuberculosis to achieve the goals of decompression of the cord followed by immobilization and antituberculous therapy. These range from conservative regimens of computed tomography-guided biopsy followed by bed rest and drug therapy to radical surgeries that involve extensive debridement of the vertebral body followed by instrumentation. The authors report their experience with a “middle path” regimen of transpedicular decompression followed by external immobilization and antituberculous therapy. Methods. The charts of 11 patients were reviewed retrospectively for clinical outcome, and kyphotic angle was measured on the follow-up radiographs to ascertain progression of kyphosis. Results. There was no worsening of the neurologic status in any patient, and 10 of the 11 patients returned to functional activity. There was no significant progression of kyphosis. Conclusions. Our results show that the transpedicular approach is a viable and safe surgical option for ventral decompression in thoracic spine tuberculosis, followed by chemotherapy for 18 months and immobilization in an alkathene shell for 3 months.

Endocrinological outcomes following endoscopic and microscopic transsphenoidal surgery in 113 patients with acromegaly

BACKGROUND To describe outcomes and complications in patients undergoing transsphenoidal surgery for acromegaly using the 2010 consensus criteria for biochemical remission. METHODS Retrospective review of 113 treatment naïve patients who underwent transsphenoidal surgery with the endoscopic (n=66) and the endonasal microscopic technique (n=47). Cure was defined if the age and sex-adjusted IGF-1 level was normal and either the basal GH was <1 ng/ml or the nadir GH was <0.4 ng/ml following oral glucose suppression at last follow-up. RESULTS The mean age at presentation was 38.1 ± 7.1 years and 86% of tumors were macroadenomas. Adenoma sizes averaged 21.1 ± 9.7 mm, but 56% of all tumors were ≥ 2 cm in size and 43.4% were invasive. Remission rates between endoscopic and microscopic transsphenoidal surgery did not differ significantly overall (28.8% versus 36.2%). On univariate analysis, a preoperative GH level <40 ng/ml, adenoma size <20mm and non-invasiveness were predictors of remission at follow-up. Although there were no statistically significant differences in remission rates between the endoscopic and microsurgical groups, surgically induced hypopituitarism was less frequent with the former. CONCLUSIONS We report our surgical experience with predominantly large, invasive GH adenomas using the 2010 criteria for cure. Patients with smaller, non-invasive tumors with lower preoperative GH levels are most likely to achieve remission. Outcomes with either the microscopic or endoscopic approach do not differ significantly, although the rate of surgically induced hypopituitarism may be higher with the former. Transsphenoidal surgery remains the first line of treatment for patients with acromegaly, but invasive adenomas will frequently require adjuvant therapy.

Decompressive craniectomy in cerebral venous thrombosis: a single centre experience

Background Cerebral venous thrombosis (CVT) is an important cause for stroke in the young where the role for decompressive craniectomy is not well established. Objective To analyse the outcome of CVT patients treated with decompressive craniectomy. Methods Clinical and imaging features, preoperative findings and long-term outcome of patients with CVT who underwent decompressive craniectomy were analysed. Results Over 10 years (2002–2011), 44/587 (7.4%) patients with CVT underwent decompressive craniectomy. Diagnosis of CVT was based on magnetic resonance venography (MRV)/inferior vena cava (IVC). Decision for surgery was taken at admission in 19/44 (43%), within 12 h in 5/44 (11%), within first 48 h in 15/44 (34%) and beyond 48 h in 10/44 (22%). Presence of midline shift of ≥10 mm (p<0.0009) and large infarct volume (mean 146.63 ml; SD 52.459, p<0.001) on the baseline scan influenced the decision for immediate surgery. Hemicraniectomy was done in 38/44 (86%) and bifrontal craniectomy in 6/44 (13.6%). Mortality was 9/44 (20%). On multivariate analysis (5% level of significance) age <40 years and surgery within 12 h significantly increased survival. Mean follow-up was 25.5 months (range 3–66 months), 26/35 (74%) had 1 year follow-up. Modified Rankin Scale (mRs) continued to improve even after 6 months with 27/35 (77%) of survivors achieving mRs of ≤2. Conclusions This is the largest series on decompressive craniectomy for CVT in literature to date. Decompressive craniotomy should be considered as a treatment option in large venous infarcts. Very good outcomes can be expected especially if done early and in those below 40 years.

Clinicopathologic correlates of giant pituitary adenomas.

Giant adenomas comprise a clinical/therapeutic subset of pituitary adenomas that pose a surgical challenge. The study population consisted of 28 patients who had giant pituitary adenomas, which are defined as tumors with a diameter greater than 5cm. Clinically, five tumors (18%) were endocrinologically functional and 23 (82%) were not. During surgery, one tumor was radically excised, four were subtotally excised, 12 were partially excised, and 11 were biopsied. All of the tumors showed typical histological features of pituitary adenoma. Of the 23 clinically non-functional adenomas, 18 were gonadotrophic tumors, four were null cell adenomas and one was a silent corticotroph adenoma. The MIB-1 labeling indices ranged from 0.1% to 2.0%. The mean topoisomerase labeling index was 0.75%. Microvessel density ranged from 0.42% to 5.55%, and there was moderately intense immunostaining for vascular endothelial growth factor. The present study found giant adenomas to be invasive but slow growing, histologically benign and often gonadotrophic in subtype.

Diagnostic and staged stereotactic aspiration of multiple bihemispheric pyogenic brain abscesses

BACKGROUND Empiric antibiotic therapy for multiple brain abscesses is not advised, as biopsy to rule out other causes and material for cultures can be obtained with minimal morbidity using computed tomography (CT)-guided stereotaxy. METHODS We report a good outcome following treatment of this 60-year-old nonimmunocompromised patient with six pyogenic cerebral abscesses. CT-guided stereotactic aspiration of two abscesses were done on the first occasion and appropriate antibiotics were administered. Serial CT scans were done and the abscesses that recollected or enlarged were again aspirated. RESULTS Group A beta hemolytic streptococci were grown from the pus. Two abscesses recollected and one enlarged during antibiotic therapy. These were aspirated on the second and third occasions, 1 week and 2 weeks after the first procedure. The abscess less than 3 cm resolved with antibiotics alone. Intravenous crystalline penicillin, chloroamphenicol, and metronidazole were given for 2 weeks followed by oral ampicillin and cotrimoxazole for 10 weeks. There was no morbidity related to the multiple procedures and the patient had a good outcome at the end of 16 weeks. CONCLUSIONS CT-guided stereotactic aspiration of multiple brain abscesses is known to have a low morbidity and mortality. We highlight the additional option of multiple, staged aspirations for those abscesses not readily responding to antibiotic therapy.

To assess the ability of MRI to predict consistency of pituitary macroadenomas

We prospectively studied the ability of magnetic resonance imaging (MRI) to predict the consistency of pituitary adenomas. The hypothesis was that firm, fibrous tumours would appear homogeneously hypointense on T2-weighted images. Eighty patients who underwent surgery for pituitary macroadenomas were studied. MR images were evaluated preoperatively by the radiologist. The tumour consistency was reported by the surgeon as soft or firm. There were 68 soft tumours and 12 firm tumours. Of the firm tumours, four (33%) were homogeneously isointense, one (8%) homogeneously hyperintense and seven (59%) were heterogeneous in appearance in T2-weighted images. We conclude that the consistency of pituitary macroadenomas cannot be accurately predicted based on MRI signal intensities.