Veer Singh Mehta

Effect of intramedullary signal changes on the surgical outcome of patients with cervical spondylotic myelopathy.

BACKGROUND CONTEXT Intramedullary signal intensity changes on magnetic resonance imaging (MRI) in cervical spondylotic myelopathy are thought to be indicative of the prognosis. However, the prognostic significance of signal intensity changes remains controversial. PURPOSE To determine the radiographic and clinical factors that correlate with the prognosis after surgery in patients with cervical spondylotic myelopathy and to investigate the factors affecting the outcome of intramedullary signal changes on MRI. STUDY DESIGN A prospective study evaluating clinical parameters and MRI in consecutive patients operated on for cervical spondylotic myelopathy. PATIENT SAMPLE A total of 146 consecutive patients with cervical spondylotic myelopathy operated on during a 2-year period (September 1999 to September 2001) formed the study group. OUTCOME MEASURES Age, duration of symptoms, number of cervical prolapsed intervertebral discs, surgical approach, preoperative signal changes, residual compression and postoperative outcome of signal changes; clinical outcome (motor, sensory, autonomic and disability improvement). METHODS The participants in this study underwent anterior cervical discectomy/corpectomy or laminectomy/laminoplasty for cervical spondylotic myelopathy. Clinical features and MRI findings were studied in detail and compared with postoperative clinical and radiological status. The spinal cord signal intensity changes were evaluated before and after surgery. The multifactorial effect of such variables as age, duration of symptoms, number of prolapsed intervertebral discs, surgical approach (anterior/posterior), preoperative cord changes on T1- and T2-weighted sequences and persistence/regression of cord changes on clinical outcome (motor/sensory/autonomic/disability improvement) was studied using stepwise logistic regression. The highlight of the study is the analysis of the factors affecting regression of cord changes and their effect on postoperative outcome. RESULTS Preoperative intramedullary signal changes were present in 121 of 146 patients (82.9%); of these 121 patients, T1- and T2-weighted images were present in 81, and T2-weighted images were present in 40 (no patient had isolated T1 change). Postoperative MRI could be obtained in 44 of 121 patients (36.4%) with preoperative intramedullary signal changes; 14 had regression of cord changes. There was no significant difference in the clinical presentation of patients with and without cord changes. There was a significant correlation between the surgical outcome of patients and their age, duration of symptoms, number of cervical prolapsed intervertebral discs, surgical approach, preoperative signal changes, residual compression and postoperative outcome of signal changes. The patients with no intramedullary signal changes and signal changes only on T2-weighted images had a better outcome than patients with signal changes on both T1- and T2-weighted images. The patients with regression of intramedullary signal changes had significantly better outcome. There was no significant correlation between regression of signal changes and other factors. However, chronicity of disease, multiplicity of discs and postoperative residual compression relatively affect persistence of intramedullary signal changes. CONCLUSIONS The presence of intramedullary signal changes on T1- as well as T2-weighted sequences on MRI in patients with cervical spondylotic myelopathy indicates a poor prognosis. However, the T2 signal intensity changes reflect a broad spectrum of spinal cord reparative potentials. Predictors of surgical outcomes are preoperative signal intensity change patterns of the spinal cord and their postoperative persistence/regression on radiological evaluations, age at the time of surgery, multiplicity of involvement and chronicity of the disease and surgical approach (anterior/posterior).

Are childhood and adult medulloblastomas different? A comparative study of clinicopathological features, proliferation index and apoptotic index.

Childhood medulloblastomas have been suspected to be biologically different from adult tumors, though comparative studies are sparse in the literature. The present study aims to establish any differences or nexus in the biological characteristics between childhood and adult medulloblastomas. A total of 181 medulloblastomas were studied with respect to clinical and histological characteristics, MIB-1 labeling index (MIB-1 LI), apoptotic index (AI), ratio of apoptotic to LI, p53 and Bcl-2 protein expressions. Two-thirds (112) of the 181 medulloblastomas occurred in children (≤15 years) and 69 in adults (>15 years). Childhood tumors were more commonly of classical histology and midline location while the desmoplastic variant and lateral location occurred more frequently in adults. Adult medulloblastomas were biologically less aggressive, having lower growth rate parameters (mean MIB-1 LI 19.1 ± 15.7; AI 3.73 ± 2.71 and AI : LI 0.207 ± 0.162) as compared to childhood tumors (mean MIB-1 LI 28.3 ± 20.4; AI 2.86 ± 2.14 and AI : LI 0.108 ± 0.111). p53 and Bcl-2 protein expressions were infrequent in all groups of tumors. No difference was noted in any of the parameters when classical and desmoplastic medulloblastomas were compared as a whole. But when compared between the age groups, an interesting observation (hitherto unreported in English literature) was that both classical and desmoplastic variants of childhood medulloblastomas had higher LI, lower AI and lower AI : LI ratio than their counterparts in adults, indicating that differences in growth rates cannot be attributed to differences in the frequency of occurrence of the histological variants in the two age groups. Thus, this study conclusively shows that there is a biological difference between childhood and adult medulloblastomas which is independent of standard histology and appeared to be associated more with age-related factors. This also warrants less-aggressive therapy for adult medulloblastoma.

Surgical management of giant intracranial aneurysms.

OBJECTIVES The natural history of giant intracranial aneurysms is generally morbid. Mortality and morbidity associated with giant aneurysms is also higher than for smaller aneurysms. This study was carried out to assess the demographic profile, presenting features, complications, and outcome after surgical treatment of giant intracranial aneurysms. PATIENTS AND METHODS A retrospective review of the medical records of all patients with giant intracranial aneurysms treated in the Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, from January 1995 through June 2007 was performed. The demographic profiles, presenting features, radiological findings, surgical treatments, and outcomes were assessed. RESULTS A total of 1412 patients harboring 1675 aneurysms were treated. Out of these, 222 patients had 229 (13.7%) giant aneurysms, and of those, 181 aneurysms in 177 patients were managed surgically while 48 were treated with endovascular therapy. In the patients treated with surgery, common clinical presentations included subarachnoid hemorrhage (SAH) in 110 (62%) cases followed by mass effect in 57 (32%) cases. In patients who presented with SAH, the Hunt and Hess SAH grading was: grade I in 43 (39%), grade II in 40 (36%), grade III in 23 (21%), grade IV in two (2%), and grade V in 2 (2%) patients. One hundred and seven aneurysms (in 103 patients) were treated using direct surgical clipping. Forty-six patients with good collateral circulation were treated by gradual occlusion and ligation of the internal carotid artery (ICA) in the neck with a Silverstone clamp. Another nine patients with good collateral circulation, but persisting symptoms after ICA ligation, required trapping for obliteration of the aneurysm. Eleven patients with poor collateral circulation required extracranial-intracranial (EC-IC) bypass before proximal ICA ligation. A post-operative digital subtraction angiography (DSA) was performed in 118 patients and revealed well-obliterated aneurysm in 106 patients. The total treatment mortality rate was 9%. In the last 5 years, 117 patients were operated on with four operative deaths. Overall, the outcome was excellent in 131 (74.0%), good in 22 (12.4%), and poor in eight (4.5%) cases. CONCLUSIONS It is concluded that 14% of all intracranial aneurysms are giant. The most common clinical presentation is SAH followed by features of an intracranial mass lesion. The cavernous ICA is the most common portion of the ICA affected. Direct surgical clipping is a safe and effective method of treatment and should be considered the first line of treatment whenever possible. With proper case selection, optimal radiological evaluation, and appropriate surgical strategy, it is possible to achieve a favorable outcome in almost 90% of the cases.

Clinicopathological features, MIB-1 labeling index and apoptotic index in recurrent astrocytic tumors

This is a study of 64 cases of recurrent astrocytic tumors of all four WHO grades wherein a comparative evaluation of initial vs. recurrent tumor was done with respect to histological grading, MIB-1 labeling index (LI) and apoptotic index (AI). The aim was to identify factor/s that could influence interval to recurrence and/or malignant progression. Recurrence was noted in all grades and upon recurrence, 93.3% of grade II (low grade diffuse) astrocytomas and 63.6% of grade III anaplastic astrocytomas underwent malignant progression. However, none of the Grade I tumors showed evidence of malignant progression. Though interval to recurrence varied considerably, there was a correlation with histological grade of the initial tumor in that grade I and II tumors had a significantly longer mean interval to recurrence (43 months and 54.8 months respectively) as compared to grade III and IV (glioblastoma multiforme) tumors (17.6 and 12.8 months respectively). The interval to recurrence was also longer for grade II and III tumors which showed progression on recurrence (55.3 months for Grade II → Grade III; 54 months for Grade II → Grade IV and 20.6 months for Grade III → IV) as compared to tumors which recurred to the same grade (12.5 months for Grade III → Grade III and 12.8 months for Grade IV→ Grade IV). A statistically significant inverse correlation of MIB-1 LI with interval to recurrence was noted. Higher the MIB-1 LI, shorter was the interval to recurrence. Further a cut off MIB-1 LI value of 2.8% could be proposed in predicting recurrence free survival. Interestingly, MIB-1 LI of grade II tumors, which had progressed to grade IV was significantly higher than MIB-1 LI of grade II tumors which had progressed to grade III. Thus, this study establishes the potential role of MIB-1 LI of the initial tumor in determining interval to recurrence. However, apoptotic index has no role in predicting either interval to recurrence or malignant progression.

Intraventricular neurocytoma: a clinicopathological study of 20 cases with review of the literature.

The clinicopathological features of 20 cases of central neurocytomas are described. They accounted for 0.28% of all intracranial tumours diagnosed during a 16 year period (1980-1995). Lower mean age of the patients at diagnosis (23.1 years), male preponderance (M:F=1.8:1) and higher incidence of involvement of the right lateral ventricle (10/20 cases) were noted in this series, in contrast to reports from Western literature. Total removal of the tumour was done in 14 cases while the remaining six underwent partial resection. Morphogically, the tumours had a striking resemblance to oligodendrogliomas (11/20 had been earlier diagnosed as oligodendrogliomas) and an interesting finding was the presence of dilated vascular channels in 12/20 tumours. The diagnosis was confirmed in all cases by immunohistochemistry and/or electron microscopy. While 18 cases were histologically benign, two had features of atypical neurocytoma. Five patients died due to postoperative complications. The remaining patients received postoperative radiation and their follow-up revealed that all of them were doing well at 12 to 72 months after surgery. These neoplasms should be suspected in any young patient with radiological evidence of an intraventricular lesion; for their differentiation from gliomas, immunohistochemistry and electron microscopy should be done. This is important because, unlike gliomas, these tumours have a relatively favourable prognosis and their current treatment of choice is complete surgical removal without adjuvant chemo- or radiotherapy. Copyright 1999 Harcourt Publishers Ltd.

Memory and intelligence outcome following surgery for intractable temporal lobe epilepsy: relationship to seizure outcome and evaluation using a customized neuropsychological battery

The main objectives of this prospective study were to (1) assess memory and intelligence outcome following surgery for intractable temporal lobe epilepsy, (2) correlate this with seizure outcome and side of surgery, and (3) perform (1) and (2) using an indigenously developed battery customized to the Indian population. Prior to use in our epilepsy surgery program, the test-retest and interexaminer variance reliability of this battery had been established in both normal and cognitively compromised populations. The memory scores were overall rather than material-specific. The battery was administered to right-handed adults undergoing surgery for intractable temporal lobe epilepsy without any evidence of opposite temporal lobe abnormality, both presurgery and postsurgery at a mean follow-up of 8 months. Twenty-five consecutive patients were included; 13 underwent right and 12 underwent left temporal surgery. Seizure outcome was assessed using Engels classification. Among 13 patients who underwent right temporal surgery, although 4 patients with poor seizure outcome had insignificant changes in scores, 7 of 9 patients with good seizure outcome exhibited considerable (> 20% over preoperative) improvement in their memory and intelligence scores. Statistical analysis using Students t test and the Mann-Whitney test revealed that the patients who underwent right temporal surgery with good seizure outcome had significant improvement in both memory (P = 0.007) and intelligence (P = 0.043) scores compared with those with poor seizure outcome. In contrast, patients who underwent left temporal surgery had no significant change in cognitive scores irrespective of seizure outcome. Cognitive improvement seems to occur in patients with good seizure outcome following nondominant temporal lobe surgery for intractable epilepsy with no evidence of pathology in the opposite temporal lobe. The same finding was not observed in patients undergoing left temporal surgery.

The microbial spectrum of brain abscess with special reference to anaerobic bacteria

The bacteriological and clinical findings of 18 cases of brain abscess are presented. Identification and antimicrobial susceptibility of anaerobic strains was performed both by conventional methods and the newer RapID ANA II panel and E-test methods, respectively. Characterization of the anaerobic isolates was done by restriction fragment length polymorphism (RFLP). Anaerobic or aerobic organisms alone were recovered in three (16.6%), and mixed aerobic and anaerobic in another three (16.6%) patients. There were nine anaerobic isolates. The predominant anaerobes were Prevotella melaninogenicus (four isolates), Bacteroides preacutus (three isolates), Fusobacterium nucleatum and Peptostreptococcus sp. (one isolate each). A total of six aerobic isolates, all of which were Gram-positive cocci were recovered. All the anaerobic isolates were susceptible to metronidazole, but two isolates of P. melaninogenicus were resistant to penicillin. There was complete agreement between the identification based on biochemical profiles and RFLP patterns. These findings indicate the microbial complexity of brain abscess and the need to target antimicrobial therapy against both the aerobic and anaerobic components of infection.

Surgical treatment of brachial plexus injuries

Ninety-nine consecutive patients with brachial plexus injuries were operated upon over a period of 8 1/2 years. Among them, 70% sustained traction injuries. The surgical procedures included neurolysis in 35, excision of a lateral neuroma in six and interfascicular sural nerve grafting in 27 patients. In 25 patients, after an exploration, no further surgical procedure was carried out. In four patients, an intercosto-musculocutaneous anastomosis, and in two a trapezius muscle transplant were carried out. Just over two-thirds (68%) of the patients were operated upon 6 months after the injury. Water soluble contrast myelography was performed in 60 patients. These included patients where a root injury had been diagnosed clinically or electrophysiologically. MRI was performed in 14 patients to visualize root avulsions and distal lesions. Operative confirmation of MRI findings were obtained in more than 85% of patients. While an early improvement was seen in patients where only a neurolysis was required, at longer follow-up, gratifying results were recorded even in patients with interfascicular grafts of 6-8 cm length. All 49 patients who came for follow-up and in whom a definitive surgical procedure had been carried out improved. Of these patients, 61% showed near normal or satisfactory functional recovery. The other patients were followed for periods of less than 1.5 years and may show further improvement with time.

Factors influencing early complications following Gamma Knife radiosurgery. A prospective study.

Purpose: The factors influencing early complications following Gamma Knife radiosurgery have not been definitely established. We report a prospective study evaluating the incidence of early complications (occurring within 3 months of radiosurgery) and various factors associated with early complications following stereotactic Gamma Knife radiosurgery for intracranial lesions. Patients and Methods: Seventy-nine previously unirradiated consecutive adult patients (82 lesions: arteriovenous malformations 35, benign tumors 43, metastases 4) treated by Gamma Knife radiosurgery were studied between May 1997 and August 1998. The median target volume was 4.8 cm3. The median dose of 15 Gy was prescribed to the 50% isodose. Patients were evaluated clinically and radiologically (with CT/MRI/SPECT) at 3-month intervals for the 1st year and 6 monthly thereafter. Complications were further divided as immediate (occurring within 24 h) or acute (occurring from 1 day to 3 months). Results: Early complications were observed in 19/79 (24.0%) patients. These included immediate in 10 (12.7%) and acute complications in 9 (11.3%) patients and were characterized by headache, nausea/vomiting, vertigo and seizures. No severe early complications were observed. Radiological changes in the form of perilesional edema were seen in 8/82 (9.8%) lesions. Maximum target diameter >25 mm was the only factor significantly associated with early complications by univariate analysis (p = 0.0335). Multivariate analysis revealed maximum target diameter >25 mm and prescribed dose >20 Gy to be significantly associated with early complications (p = 0.0442 and p = 0.0083, respectively). Conclusion: Up to one fourth of the patients undergoing Gamma Knife radiosurgery for intracranial lesions can experience self-limiting early toxicity. The selection of targets with small diameter and volume may reduce the risk of early complications following Gamma Knife radiosurgery.

Cerebellopontine angle paraganglioma - report of a case and review of literature.

SummaryMajority of the cerebellopontine angle (CPA) tumors are acoustic neuromas, while bulk of the non-acoustic tumors are formed by meningiomas and epidermoid cysts. Primary paraganglioma is a rare tumor in this location, with only two such cases having been reported in the literature, till date. Recently, a case has been described wherein a paraganglioma was apparently arising as a primary lesion in the cerebellar hemisphere. We report another case of an intracranial paraganglioma of the CPA in a 40-year-old female, which did not have any vascular attachment but had focal cerebellar extension.