Mathew J. Chandy

Management of Neurosurgical Patients with Hyponatremia and Natriuresis

The main objective of our study was to evolve a practical management protocol for neurosurgical patients with hyponatremia and natriuresis, based on their blood volume status and hematocrit. Twenty-one patients with hyponatremia and natriuresis and 3 control patients were studied. Patients with hyponatremia were categorized on the basis of their hematocrit, central venous pressure, and total blood volume. Group A consisted of patients with hypovolemia and anemia (16 patients); Group B patients had hypovolemia but no anemia (5 patients); Group C included those with hypervolemia (0 patients). Patients in Groups A and B received isotonic saline (> 50 ml/kg/d) and oral salt (12 g/d). Additionally, those in Group A were transfused with 500 ml of whole blood. The end points in the study were 72 hours after entry or two consecutive serum sodium values of > 130 mEq/L, whichever was earlier. Hyponatremia was corrected in all the patients within 72 hours (1 patient, < 24 h; 13 patients, < 48 h; and 7 patients, < 72 h). We conclude that most neurosurgical patients with hyponatremia and natriuresis have hypovolemia, with or without anemia. Fluid and salt replacement and a blood transfusion rather than fluid restriction often results in the correction of the hyponatremia. Our findings offer indirect evidence to support the hypothesis that in most of these patients, hyponatremia is caused by cerebral salt wasting syndrome, rather than the syndrome of inappropriate secretion of antidiuretic hormone.

Validation of diagnostic criteria for solitary cerebral cysticercus granuloma in patients presenting with seizures

Objective ‐ To evaluate a set of clinical and computed tomographic (CT) criteria (previously described by us) to predict the diagnosis of a solitary cerebral cysticercus granuloma (SCCG) at initial presentation, in patients presenting with seizures. Material and methods ‐ The diagnostic criteria were applied prospectively to patients presenting with seizures and solitary lesion on the CT scan. The clinical diagnostic criteria were as follows: seizures should be the presenting complaint; there should be no evidence of persistent raised intracranial pressure, progressive neurological deficit or an active systemic disease. The CT diagnostic criteria were: evidence of a solitary contrast enhancing lesion measuring 20 mm or less in its maximal dimension without a shift of the midline structures due to the surrounding oedema. A diagnosis of SCCG was made only when all the clinical and CT criteria were fulfilled. Over a period of 36 months, we managed 401 patients presenting with seizures and a solitary mass on the CT scan; 215 met the criteria for the diagnosis of an SCCG. Results ‐ Of the 215 patients initially diagnosed to have an SCCG, 197 were ultimately determined to have that diagnosis (true positive diagnosis) while 16 were excluded because of lack of follow‐up CT assessment. Two of the 215 patients with the initial diagnosis of an SCCG subsequently had histological diagnosis of a secondary metastasis and a pyogenic abscess (false positive diagnosis). Our set of diagnostic criteria for SCCG had a sensitivity of 99.5%; specificity of 98.9%; a positive predictive value of 99%; and a negative predictive value of 99.5%. The likelihood ratios for the positive and negative tests were 92.99 and 0.005 respectively. Conclusions ‐ Our diagnostic criteria help in not only accurately identifying an SCCG but also in differentiating it from a solitary tuberculoma and other brain masses. However, confirmation of the diagnosis of an SCCG is only obtained at follow‐up evaluation and therefore careful clinical and CT re‐evaluation is essential in all patients initially diagnosed to have an SCCG.

Brainstem Glioma: Comparative Study of Clinico-Radiological Presentation, Pathology and Outcome in Children and Adults

Summary Although the clinical and imaging features and behaviour of brain stem gliomas in children are well documented, similar data are not available, for adults. We have carried out a retrospective study, on 101 consecutive patients (71 children and 30 adults) with a histologically verified brain stem glioma. Duration of symptoms, clinical features, imaging characteristics, histopathology and outcome were specifically compared in children and adults with brain stem glioma. Peak incidence was in the first decade in children and in the third and fourth decades in adults. Mean duration of symptoms before admission was 9.7 months in adults and 3.6 months in children (P<0.001). There were no significant differences in the clinical features between adults and children. Imaging characteristics revealed no major differences except that diffuse hypodense lesions involving the whole brainstem accounted for 41.2% of the lesions in children and only 11.1% of adults (P<0.001). A stereotactic biopsy was performed in 92 patients and an open biopsy or partial excision in 9 patients. Histopathological examination showed that the majority of gliomas were diagnosed as grade II astrocytomas in both groups. Survival was significantly shorter in children when compared to adults (P<0.01). While the tumour grade was a significant factor in predicting survival in adults, in children it did not correlate with outcome. Therefore, determination of the grade of a brain stem glioma may be of prognostic significance in adult patients.

Ascorbic acid and focal cerebral ischaemia in a primate model

SummaryNeuronal cell damage following ischaemia is postulated to be due to free radical induced lipid peroxidation, and ascorbic acid is supposedly an important non-enzymatic scavenger of such free radicals. This study was undertaken to evaluate the protective effect of ascorbic acid on the brain in a primate model after focal cerebral ischaemia. Consumption of ascorbic acid in the monkey brain following ischaemia and its effect on macroscopic infarct size as demonstrated by 2, 3, 5, Triphenyl tetrazolium chloride (TTC) staining were used as parameters.The monkeys in the treated group were given 1 gram ascorbic acid parenterally every day for six days. The mean level of total ascorbic acid in right basal ganglia was 35.1±4.2 μg/mg of protein in the treated group as opposed to 22.9±2.1 μg/mg of protein in the nontreated group both before ischaemia. After right middle cerebral artery occlusion to produce focal cerebral ischaemia, the total ascorbic acid in the right basal ganglia 2 hours post ischaemia was 13.3±3.1 μg/mg of protein in the treated group as opposed to 9±1.6 μg/mg of protein in the untreated group. The average consumption of total ascorbic acid was 21.8 μg/mg of protein in the treated group and 13.9 μg/mg of protein in the nontreated group.Macroscopic infarct size as determined by TTC staining in the right cerebral hemisphere was 11.7±6.9 in treated group whereas it was 24.4±4.4 (expressed as percentage of right hemisphere) in the non-treated group. There was significant reduction in the size of the infarct in the treated group.A short course of mega-dose Ascorbic acid therapy was found to significantly decrease the macroscopic infarct size. Pretreatment with ascorbic acid enhanced its storage and utilization during ischaemia resulting in its protective effect.

Predictive value of computed tomography-based diagnosis of intracranial tuberculomas.

The need to obtain histological diagnoses of intracranial tuberculomas, before initiating therapy, is not universally accepted, because some clinicians believe that an image-based diagnosis is fairly accurate in patients from endemic regions. To evaluate the sensitivity, specificity, and predictive value of computed tomography (CT)-based diagnosis of an intracranial tuberculoma, we prospectively compared the preoperative imaging diagnoses with histological diagnoses in 105 consecutive patients with intracranial masses. CT differential diagnoses (first or second) of tuberculomas were considered in 21 patients. Seven of them were histologically confirmed to have tuberculomas (true-positive results); 14 had other diseases (false-positive results). The 14 false-positive cases included 6 cases of astrocytomas, 5 of metastases, and 3 with miscellaneous diagnoses. All tuberculomas were correctly diagnosed on the CT scans (5 by both surgeons and 2 by one surgeon). During the study period, we encountered 11 patients who were referred by other clinicians with diagnoses of tuberculomas on the basis of their CT scans. We concurred with their CT diagnoses in 5 of them, but only 1 patient had a histologically verified tuberculoma. Astrocytomas (4 patients), metastases (3 patients), and solitary cysticercus granulomas (3 patients) were the causes of misdiagnosis in this group of patients. Although the sensitivity of CT in the diagnosis of intracranial tuberculomas is 100%, and its specificity is 85.7%, the positive predictive value is only 33% (confidence limits, 24-42%). The negative predictive value is 100%. The low positive predictive value for a diagnosis of intracranial tuberculoma on CT alone indicates the need for a confirming histological diagnosis.

Local wound infiltration with bupivacaine in lumbar laminectomy

BACKGROUND Parenteral administration of narcotics has been the mainstay for postoperative pain relief in patients undergoing lumbar laminectomy. However, this may lead to respiratory depression and nausea, which may be hazardous in these patients. METHODS We evaluated the efficacy of wound infiltration with bupivacaine in 45 consecutive patients undergoing elective single-level lumbar laminectomy for intervertebral disc prolapse in a prospective, double-blind, randomized controlled trial. Prior to wound closure, the muscle and subcutaneous tissues were infiltrated with bupivacaine 0.375% or sterile physiologic saline. Postoperatively, the patients were assessed hourly for pain and an analgesic administered if the patient had moderate or severe pain. RESULTS All the 21 placebo recipients required analgesics in the first 9 hours postoperatively, compared to only 11 of 24 patients who received bupivacaine (p < 0.001). The mean (standard deviation) time before administration of the first dose of analgesic postoperatively in the bupivacaine and placebo recipients was 807.7 (567.6) minutes and 181.4 (110.1) minutes, respectively (p < 0.001). No adverse effects of local wound infiltration were noted. CONCLUSIONS Local wound infiltration with bupivacaine is a safe and effective method for providing postoperative pain relief and reducing narcotic use in patients undergoing lumbar laminectomy.

Effect of Ascorbic Acid on Infarct Size in Experimental Focal Cerebral Ischaemia and Reperfusion in a Primate Model

Summary Temporary occlusion of major cerebral blood vessels occasionally becomes necessary during surgical procedures. Ascorbic acid (Vitamin C) is an important non-enzymatic scavenger of free radicals and its protective effect on the brain in permanent focal cerebral ischaemia has been proven in a primate model of focal cerebral ischaemia [16]. Additional damage caused by reperfusion of the infarcted area has been shown in the rat model [22]. This study was undertaken to study the efficacy of ascorbic acid in decreasing infarct size in ischaemic reperfused brain. Maccaca radiata monkeys in the treated group were given two grams of ascorbic acid, parentally immediately before clipping the middle cerebral artery and the control group was given placebo. Reperfusion was done after four hours. Mean infarct size in all the three brain slices in the ascorbic acid pretreated group was 7.3%±2.7 and in the placebo group 22.1±6.7 under similar conditions. The mean infarct size in the ascorbic acid pretreated group of monkeys was significantly lower when compared with the placebo group (p=0.0003).

Symptomatic Pneumocephalus after Transsphenoidal Surgery

BACKGROUND Symptomatic pneumocephalus after transsphenoidal surgery, though reported, is a rare phenomenon. We report three cases of pneumocephalus in a series of 300 transsphenoidal operations for sellar/suprasellar mass lesions done over the past 12 years. METHODS AND RESULTS Three cases of symptomatic pneumocephalus occurring after transsphenoidal surgery are presented to illustrate the causative factors, methods of prevention, and management. In case 1, an intraoperative cerebrospinal fluid (CSF) leak occurred and drainage of CSF through a lumbar subarachnoid drain resulted in pneumocephalus, in spite of repair of the sellar floor. In case 2, partial excision of tumor and subsequent reduction of intracranial pressure due to a ventriculoperitoneal (VP) shunt led to pneumocephalus. In case 3, radiotherapy-induced shrinkage of a partially excised tumor resulted in pneumocephalus. The sellar floor had not been repaired in cases 2 and 3 as there was no intraoperative CSF leak and only a partial excision had been done. Conservative management failed in the two patients in whom it was tried. Repair of the sella and sphenoid sinus had to be done in all three cases. CONCLUSIONS Repair of the sellar floor should be done after a transphenoidal approach in all cases, even when no intraoperative leak has been identified and only a partial excision of tumor has been done. Once pneumocephalus has occurred, the sellar floor and sphenoid sinus should be repaired early before reducing the intracranial pressure (ICP) by tapping ventricular air and draining or diverting CSF.

MRI features of neurosurgical gossypiboma: report of two cases

Retained surgical sponge is an uncommon complication in neurosurgical practice. We report two patients with retained surgical gauze and describe the clinical presentation and the characteristics of the foreign body on MRI.

Shunt surgery in poor grade patients with tuberculous meningitis and hydrocephalus: effects of response to external ventricular drainage and other variables on long term outcome

Thirty two poor grade patients (grade 3, 20 patients and grade 4, 12 patients) with tuberculous meningitis and hydrocephalus were prospectively studied to evaluate the response to external ventricular drainage in predicting outcome after shunt surgery. All grade 3 patients underwent a shunt procedure irrespective of their response to external ventricular drainage, and an attempt was made to correlate the immediate response to external ventricular drainage to their long term outcome. Patients in grade 4 underwent shunt surgery only if there was clinical improvement by at least one grade after external ventricular drainage. Follow up (mean 23.1 months) was available for 30 patients (93%). Of the 20 patients in grade 3, seven underwent shunt surgery directly, 13 after an external ventricular drainage. In the group which underwent drainage, the immediate clinical response was improvement in six, no change in six, and death in one. Long term improvement or death occurred almost equally in all the subgroups. The immediate response to external ventricular drainage was not predictive of the long term outcome in grade 3 patients. All 12 patients in grade 4 underwent an external ventricular drainage and only one improved. The rest continued to deteriorate and succumbed to the disease. Grade at admission was the single most important predictor of good outcome (p=0.002) and severity of hydrocephalus had an adverse impact on outcome (p= 0.04). The rest of the variables studied (age, duration of illness, duration of altered sensorium, CSF cell count, and CSF protein concentrations) had no effect on long term outcome. All patients in grade 3 should be given the benefit of shunt surgery without a trial of external ventricular drainage. However, patients in grade 4 should undergo an external ventricular drainage in view of the high mortality in this group.