Biomedical subjects

Mahesh Prakash

Publications and source records attributed to Mahesh Prakash.

6 recordsLinked to original sources

PubMed2006

Unusual split cord with neurenteric cyst and cerebellar heterotopia over spinal cord.

OBJECTIVE: To report a case of splitting of a cord, which could neither be classified as type I nor type II according to Pang's classification. The child had associated neurenteric cyst and cerebellar tissue heterotopia. CASE REPORT: A 3-year-old girl presented with a tuft of hair and dermal sinus at her upper dorsal spine. She had splitting of cord into two halves by two intradural horny osseocartilaginous spurs leaving a gap of 3 mm in between (two spurs and two halves of cords). A neurenteric cyst was seen passing from the anterior to posterior aspect of the cords through this gap. An associated heterotopic cerebellar tissue mass was encountered over the dorsum of cord proximal to splitting. The dermal sinus, neurenteric cyst, and spurs were excised to detether the cord. The heterotopic tissue was biopsied. The child had no neurological deficit at 2.5 years follow-up. CONCLUSION: An unusual splitting of cord by unusual spurs may leave a gap between two spurs and two halves of cords to pass a neurenteric cyst. Rarely, heterotopic tissue may be associated with split cord syndrome. A dermal sinus may lead into underlying neurenteric cyst (rather than dermoid).

Cerebellar Diseases↗

PubMed2006

Effect of lobe pumping on human albumin: development of a lobe pump simulator using smoothed particle hydrodynamics.

Using SPH (smoothed particle hydrodynamics), the motion of a lobe pump under load was simulated in order to predict the level of shear stress experienced by a protein solution. By varying the gap size between the lobes and pump housing, variations in pump efficiency and shear stress were determined. The simulations indicated that pump shear was dependent on gap size, with shear stress levels (0-40 Pa) correlating with those estimated in previous albumin-pumping studies. As gap size increased, the number of fluid particles experiencing low shear (<10 Pa) increased, whereas those experiencing high shear (>20 Pa) showed a decreasing trend. The pump efficiency, however, decreased with gap size, requiring more lobe revolutions to pass a unit volume. Taken together, these observations indicate that lobe pumps operated with increased gaps between the rotors and the housing result in larger number of particles within the fluid experiencing shear stresses. Moreover, the simulations indicate that it is best to use larger lobe pumps operated at high efficiency to transfer protein-containing solutions.

Albumins↗

PubMed2006

Paradoxical response to chemotherapy in neurotuberculosis.

OBJECTIVE: Our objective was to investigate the paradoxical response and the factors responsible for such an uncommon (but known) response to chemotherapy in neurotuberculosis. MATERIAL AND METHODS: Ten children with intracranial tuberculomas/neurotuberculosis were retrospectively studied, who were on regular antituberculous chemotherapy. Any deterioration of the neurological condition, increase in the size of the lesion or appearance of new lesions was studied clinically and radiologically during the follow-up period. RESULTS: An atypical response to chemotherapy was observed from 3 weeks to 1 year of chemotherapy. Four of the 10 children, who were receiving chemotherapy for either post-tubercular meningitis (TBM), hydrocephalus (2) or TBM (2), developed multiple granulomas in 3 and hydrocephalus in 1 case. The remaining 6 children who were diagnosed to have granulomas at their presentation deteriorated at the follow-up despite regular chemotherapy. CT scans were repeated in 7 of 10 cases at the time of neurological deterioration, out of which 5 children showed appearance of new granulomas or abscess(es) and 2 showed an increase in the size of their preexisting granulomas. One patient with faintly enhancing granulomas in the posterior fossa responded to an additional use of steroids. The remaining 9 patients required surgical intervention on account of their neurological deterioration. CONCLUSIONS: (1) Paradoxical responses to intracranial tuberculoma/neurotuberculosis can occur at any time even up to 1 year during chemotherapy despite a regular standard antitubercular treatment. (2) New granuloma(s) or abscess(es) may appear in children receiving chemotherapy for TBM during the follow-up. (3) Hydrocephalus may also appear despite a regular chemotherapy in treated TBM cases. (4) Immature faintly enhancing tuberculomas have a more likely chance of resolution with antituberculous chemotherapy and glucocorticoids, while a well-formed and probably large-sized (>3 cm) granuloma may have a risk of paradoxical enlargement.

Adolescent↗

PubMed2005

Role of diffusion weighted imaging in differentiation of intracranial tuberculoma and tuberculous abscess from cysticercus granulomas-a report of more than 100 lesions.

Restricted diffusion is noted in a large number of non-stroke conditions including tuberculoma. The purpose of this study was to demonstrate spectrum of diffusion weighted imaging (DWI) abnormalities in tuberculomas and tuberculous abscess and to distinguish these from degenerating neurocysticercosis. Seventy tuberculomas and tuberculous abscesses in 30 patients were categorized in three groups depending on the intensity in the core of the lesion on T2 weighted images. Mean apparent diffusion coefficient (ADC) was calculated from the core as well as from the wall of the lesions. Forty-five lesions of neurocysticercosis in different stage of evolution in 12 patients were also included for comparison. The mean ADC value from the core of the T2 hypointense lesions was significantly higher compared to the wall ((1.24+/-0.32)x10(-3) and (1.06+/-0.15)x10(-3)mm(2)/s, respectively), while mean ADC value from the core of mildly T2 hyperintense lesions was significantly lower compared to the wall ((0.80+/-0.08)x10(-3) and (1.08+/-0.13)x10(-3)mm(2)/s, respectively). Truly T2 hyperintense lesions were divided into two subgroups, tuberculomas and tuberculous abscesses; ADC values from the core and the wall of these lesions were (0.74+/-0.13)x10(-3), (0.61+/-0.08)x10(-3) and (1.03+/-0.14)x10(-3), (1.08+/-0.14)x10(-3)mm(2)/s, respectively, and was significantly lower in core as compared to the wall. However, there was no significant difference between ADC values of the tuberculous abscess and the hyperintense tuberculomas. Vesicular and degenerating stages of cysticercus cysts from the core showed ADC values of (1.66+/-0.29)x10(-3) and (1.51+/-0.23)x10(-3)mm(2)/s, respectively, and were significantly higher than the core of all groups of tuberculomas and tuberculous abscess. We conclude that addition of DWI to routine imaging protocol may help in differentiation of tuberculous lesions from degenerating cysticercus granuloma.

Adult↗

PubMed2004

Discrete-element modelling and smoothed particle hydrodynamics: potential in the environmental sciences.

Particle-based simulation methods, such as the discrete-element method and smoothed particle hydrodynamics, have specific advantages in modelling complex three-dimensional (3D) environmental fluid and particulate flows. The theory of both these methods and their relative advantages compared with traditional methods will be discussed. Examples of 3D flows on realistic topography illustrate the environmental application of these methods. These include the flooding of a river valley as a result of a dam collapse, coastal inundation by a tsunami, volcanic lava flow and landslides. Issues related to validation and quality data availability are also discussed.

Algorithms↗

PubMedDate not supplied

Diffusion-weighted MR imaging in Japanese encephalitis.

OBJECTIVE: This study was performed to evaluate the role of diffusion-weighted imaging (DWI) in the diagnosis of Japanese encephalitis (JE) and to look for any relationship of the apparent diffusion coefficient (ADC) values with duration of the illness. METHODS: We performed DWI in fourteen patients of JE. T2 weighted (T2W) and DWI were compared for number and location of lesions in all patients. Based on imaging patients were divided in three groups: group 1 (n=9) showing more lesions on DWI compared with T2W images, group 2 (n=3) with equal number of lesions on T2W and DWI and group 3 (n=2) with lesions more pronounced on T2W than DWI. ADC values were computed for all the lesions. The time interval between onset of neurologic signs/symptoms and MRI were charted and correlated with ADC values. RESULTS: DWI was helpful in making early diagnosis of JE by showing characteristic involvement of bilateral thalami in four patients. Nine out of fourteen patients showed additional lesions on DWI. ADC from lesions in groups I, II and III measured 0.648 +/- 0.099 x 10 mm/s, 0.739 +/- 0.166 x 10 mm/s and 1.123 +/- 0.185 x 10 mm/s respectively. The ADC from the lesions in group 1 was significantly lower compared with group 2 (P value <0.05) while it was higher in group 3 lesions compared with the other two groups. There was a significant direct correlation of ADC values with the disease duration in these cases (r=0.847, P <0.01). CONCLUSIONS: DWI is helpful in early diagnosis and characterization of the duration of the lesions in JE.

Adolescent↗