PubMed Health⌕ Search

Biomedical subjects

Krishna Kumar

Publications and source records attributed to Krishna Kumar.

27 records · Page 2Linked to original sources
PubMed2003

Symptomatic spinal arachnoid cysts: report of two cases with review of the literature.

STUDY DESIGN: Two unusual cases of intradural extramedullary noncommunicating arachnoid cysts are presented, with a review of literature. OBJECTIVE: To assess surgical excision results in the reversal of symptoms and neurologic deficits. SUMMARY OF BACKGROUND DATA: Most patients harboring arachnoid cysts are asymptomatic. Noncommunicating intradural extramedullary arachnoid cysts are more rare than communicating intradural extramedullary cysts. Noncommunicating intradural extramedullary arachnoid cysts are a very rare cause of spinal cord compression. Rarely, these cysts can present with bizarre symptoms, such as angina. MATERIALS AND METHODS: The first case, a 75-year-old woman, presented with progressive paraparesis. The second case, a 40-year-old man, presented with signs and symptoms of angina, with mild spasticity in the lower limbs. In both cases, magnetic resonance imaging revealed compression of the spinal cord as the etiology of presentation. The first patient is the second oldest patient in the literature with an idiopathic spinal arachnoid cyst. The second case has an unusual presentation that has not previously been reported in the literature. RESULTS: Both cases underwent surgical excision of the arachnoid cyst, with resolution of symptoms and reversal of neurologic deficit. CONCLUSIONS: Our experience indicates that complete recovery from an arachnoid cyst is possible after surgical excision, even when symptoms are present for a long duration, even in the elderly.

Adult↗
PubMed2003

Recombinant tissue plasminogen activator in the treatment of intraventricular hemorrhage secondary to periventricular arteriovenous malformation before surgery: case report.

OBJECTIVE AND IMPORTANCE: Intraventricular hemorrhage (IVH) is known to cause acute obstructive hydrocephalus, refractory elevated intracranial pressures (ICPs), and lowered cerebral perfusion pressures, leading to cortical ischemia. Frequent obstruction of external ventricular drains as a result of thrombus is a recurring theme. We present a case of IVH secondary to periventricular arteriovenous malformation (AVM) that was not visible at admission angiography and was treated by intraventricular infusion of recombinant tissue plasminogen activator before surgical intervention. CLINICAL PRESENTATION: An 11-year-old boy presented with acute onset of headache followed by two seizures, loss of consciousness, decerebration, right temporal hematoma, IVH, and acute obstructive hydrocephalus. INTERVENTION: A right external ventricular drain was placed but functioned poorly. ICP could not be controlled by conventional methods. Five milligrams of recombinant tissue plasminogen activator was injected into the ventricular system via the external ventricular drain. This was repeated daily for 4 days. This treatment resulted in progressive improvement in ICP and clinical status. Once the clot partially cleared, magnetic resonance imaging and magnetic resonance angiography suggested the presence of a right periventricular arteriovenous malformation, which was confirmed by angiography and subsequently resected. CONCLUSION: Recombinant tissue plasminogen activator is effective in resolving IVH causing obstructive hydrocephalus and uncontrollable ICP posing a life-threatening situation, secondary to ruptured arteriovenous malformation, before surgical intervention.

Cerebral Angiography↗
PubMed2002

Wavy stripes and squares in zero-Prandtl-number convection.

A simple model to explain the numerically observed behavior of chaotically varying stripes and square patterns in zero-Prandtl-number convection in Boussinesq fluid is presented. The nonlinear interaction of mutually perpendicular sets of wavy rolls, via higher-order modes, may lead to a competition between the two sets of rolls. The appearance of square patterns is due to a secondary forward bifurcation from a set of wavy rolls. The statistics of the spatially averaged energy signal shows a power-law behavior.

Journal Article↗
PubMed2002

Quasiperiodic waves at the onset of zero-Prandtl-number convection with rotation.

We show the possibility of temporally quasiperiodic waves at the onset of thermal convection in a thin horizontal layer of slowly rotating zero-Prandtl-number Boussinesq fluid confined between stress-free conducting boundaries. Two independent frequencies emerge due to an interaction between straight rolls and waves along these rolls in the presence of Coriolis force, if the Taylor number is raised above a critical value. Constructing a dynamical system for the hydrodynamical problem, the competition between the interacting instabilities is analyzed. The forward bifurcation from the conductive state is self-tuned.

Journal Article↗
PubMed2002

Fluorinated amino acids in protein design and engineering.

Selective incorporation of unnatural amino acids into proteins is a powerful tool for illuminating the principles of protein design. In particular, fluorinated amino acids have recently emerged as valuable building blocks for designing hyperstable protein folds, as well as directing highly specific protein-protein interactions. We review the collagen mimetic and coiled coil peptide systems that exemplify generalizable paradigms for future design. The unique electronic and phase properties of fluorocarbons are discussed, and protein synthesis using unnatural amino acids is briefly reviewed.

Amino Acids↗
PubMed2002

Treatment of chronic pain with spinal cord stimulation versus alternative therapies: cost-effectiveness analysis.

OBJECTIVE: There is limited available research measuring the cost-effectiveness of spinal cord stimulation (SCS), compared with best medical treatment/conventional pain therapy (CPT). The purpose of this study was to tabulate the actual costs (in Canadian dollars) for a consecutive series of patients treated with SCS in a constant health care delivery environment and to compare the costs with those for a control group treated in the same controlled environment. METHODS: We present a consecutive series of 104 patients with failed back syndrome. Within this group, 60 patients underwent SCS electrode implantation, whereas 44 patients were designated as control subjects. We monitored these patients for a 5-year period and tabulated the actual costs incurred in diagnostic imaging, professional fees paid to physicians, implantation (including the costs for hardware), nursing visits for maintenance of the stimulators, physiotherapy, chiropractic treatments, massage therapy, and hospitalization for treatment of breakthrough pain. From these data, the cumulative costs for each group were calculated for a 5-year period. An analysis of Oswestry questionnaire results was also performed, to evaluate the effects of treatment on the quality of life. RESULTS: The actual mean cumulative cost for SCS therapy for a 5-year period was $29,123/patient, compared with $38,029 for CPT. The cost of treatment for the SCS group was greater than that for the CPT group in the first 2.5 years. The costs of treating patients with SCS became less than those for CPT after that period and remained so during the rest of the follow-up period. In addition, 15% of SCS-treated patients were able to return to employment, because of superior pain control and lower drug intake. No patients in the control group were able to return to employment of any kind. CONCLUSION: SCS is cost-effective in the long term, despite the initial high costs of the implantable devices.

Back Pain↗
PubMed2002

Treatment of chronic pain by using intrathecal drug therapy compared with conventional pain therapies: a cost-effectiveness analysis.

OBJECT: The object of this study was to compare the cost-effectiveness of intrathecal drug therapy (IDT) with that of conventional pain therapy (CPT) in patients suffering from chronic low back pain caused by failed back syndrome. In this study, the authors tabulated actual costs, in Canadian dollars, in a consecutive series of patients undergoing IDT within the Canadian health care system and have compared them with costs in a control group in the same environment. The influence of these treatments on the quality of life (QOL) was also analyzed. METHODS: The authors report on a series of 67 patients suffering from failed back syndrome, 23 of whom underwent implantation of a programmable drug delivery pump and 44 of whom acted as controls. Patients were followed for a 5-year period during which the investigators tabulated the actual costs incurred for diagnostic imaging, professional fees, implantation costs including hardware, nursing visits for maintenance of the pumps, alternative therapies, and hospitalization costs for breakthrough pain. From this data, cumulative costs for each group were calculated for a 5-year period. Patient responses on the Oswestry Pain Questionnaire were analyzed to assess the impact of treatment on QOL. The actual cumulative costs for IDT during a 5-year period were $29,410, as opposed to $38,000 for CPT. High initial costs of equipment required for IDT were recovered by 28 months. After this time point, managing patients with CPT became the more expensive treatment option for the remainder of the follow-up period. The Oswestry Disability Index showed a 27% improvement for patients in the IDT group, compared with a 12% improvement in the control group. CONCLUSIONS: In patients who respond to this treatment, IDT is cost effective in the long term despite high initial costs of implantable devices.

Analgesics, Opioid↗