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Sumit Thakar, Narayanam Anantha Sai Kiran and Alangar S. Hegde

Spinal extradural arachnoid cysts (ACs) have an infrequent predilection for the sacrum. As with their counterparts in other regions of the spine, cysts in this location are mostly asymptomatic. Common presentations in symptomatic cases include pain in the low back or perineum, radiculopathy, and sphincteric dysfunction. The authors report a hitherto undescribed presentation in which the predominant symptoms are those related to an associated holocord syrinx. This 15-year-old boy presented with fluctuating, spastic paraparesis and a dissociated sensory loss in the trunk. Admission MR imaging of the spine showed an extradural AC from S-2 to S-4 and a holocord, nonenhancing syrinx. The patient underwent S-2 laminectomy, fenestration of the cyst, and partial excision of its wall. Intradural exploration revealed a normal-looking filum terminale and the absence of any dural communication with the cyst. At a follow-up visit 6 months after surgery, his motor and sensory deficits had resolved. Follow-up MR imaging showed complete resolution of the syrinx in the absence of the sacral AC. This is the first report of a sacral extradural AC causing holocord syringomyelia. Because conventional theories of syrinx formation were not helpful in elucidating this case, a hypothesis is postulated to explain the clinicoradiological oddity.

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Sumit Thakar, Avinash Kurudi Siddappa, Saritha Aryan, Dilip Mohan, Narayanam Anantha Sai Kiran and Alangar S. Hegde

OBJECTIVE

The mesodermal derangement in Chiari Type I malformation (CMI) has been postulated to encompass the cervical spine. The objectives of this study were to assess the cross-sectional areas (CSAs) of cervical paraspinal muscles (PSMs) in patients with CMI without syringomyelia, compare them with those in non-CMI subjects, and evaluate their correlations with various factors.

METHODS

In this retrospective study, the CSAs of cervical PSMs in 25 patients were calculated on T2-weighted axial MR images and computed as ratios with respect to the corresponding vertebral body areas. These values and the cervical taper ratios were then compared with those of age- and sex-matched non-CMI subjects and analyzed with respect to demographic data and clinicoradiological factors.

RESULTS

Compared with the non-CMI group, the mean CSA values for the rectus capitis minor and all of the subaxial PSMs were lower in the study group, and those of the deep extensors were significantly lower (p = 0.004). The cervical taper ratio was found to be significantly higher in the study cohort (p = 0.0003). A longer duration of symptoms and a steeper cervical taper ratio were independently associated with lower CSA values for the deep extensors (p = 0.04 and p = 0.03, respectively). The presence of neck pain was associated with a lower CSA value for the deep flexors (p = 0.03).

CONCLUSIONS

Patients with CMI demonstrate alterations in their cervical paraspinal musculature even in the absence of coexistent syringomyelia. Their deep extensor muscles undergo significant atrophic changes that worsen with the duration of their symptoms. This could be related to a significantly steeper cervical taper ratio that their cervical cords are exposed to. Neck pain in these patients is related to atrophy of their deep flexor muscles. A steeper cervical taper ratio and alterations in the PSMs could be additional indicators for surgery in patients with CMI without syringomyelia.

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Narayanam Anantha Sai Kiran, Sandeep Vaishya, Shashank Sharad Kale, Bhavani Shankar Sharma and Ashok Kumar Mahapatra

Object

Significant numbers of patients with spinal tuberculosis (TB), especially in developing countries, still present late after disease onset with severe neurological deficits. The authors conducted a study to assess the outcome in these patients.

Methods

Fifty-nine patients with spinal TB and severe motor deficits underwent surgery at the authors' center during the past 10 years. Data obtained in 48 patients with a minimum of 3 months of follow up (mean follow-up period 12.8 months) were analyzed. The disease in 34 patients was characterized by Frankel Grade A/B (Medical Research Council Grade 0/5) and in 14 patients by Frankel Grade C (unable to walk even with support) at admission. Thirty (88%) of the 34 patients with Frankel Grade A/B status and 13 (92.8%) of the 14 patients with Frankel Grade C status at admission experienced improvement to Frankel Grade D/E (walking with or without support) at the last follow-up examination 3 or more months after surgery. The degree of improvement exhibited by patients with a Frankel Grade A/B spinal cord injury was comparable to that shown by patients with Frankel Grade C status. Even patients with flaccid paraplegia, gross sensory deficit, prolonged weakness, spinal cord signal changes demonstrated on magnetic resonance imaging, and bladder involvement have experienced dramatic improvement in motor function since surgery. A significant number of the patients have shown remarkable improvement in other symptoms such as pain (91.6%), spasticity (88%), and bladder symptoms (88%).

Conclusions

A significant proportion of patients with spinal TB and severe motor deficits experience remarkable improvement after surgical decompression and hence should undergo surgery even though they may be suffering from paraplegia of considerable duration.

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Sumit Thakar, Laxminadh Sivaraju, Saritha Aryan, Dilip Mohan, Narayanam Anantha Sai Kiran and Alangar S. Hegde

OBJECTIVE

The objective of this study was to assess the cross-sectional areas (CSAs) of lumbar paraspinal muscles in adults with isthmic spondylolisthesis (IS), to compare them with those in the normative population, and to evaluate their correlations with demographic factors and MRI changes in various spinal elements.

METHODS

The authors conducted a retrospective study of patients who had undergone posterior lumbar interbody fusion for IS, and 2 of the authors acting as independent observers calculated the CSAs of various lumbar paraspinal muscles (psoas, erector spinae [ES], multifidus [MF]) on preoperative axial T2-weighted MR images from the L-3 to L-5 vertebral levels and computed the CSAs as ratios with respect to the corresponding vertebral body areas. These values were then compared with those in an age- and sex-matched normative population and were analyzed with respect to age, sex, duration of symptoms, grade of listhesis, and various MRI changes at the level of the listhesis (pedicle signal change, disc degeneration, and facetal arthropathy).

RESULTS

Compared with values in normative controls, the mean CSA value for the ES muscle was significantly higher in the study cohort of 120 patients (p = 0.002), whereas that for the MF muscle was significantly lower (p = 0.009), and more so in the patients with PSC (p = 0.002). Magnetic resonance imaging signal change in the pedicle was seen in half of the patients, all of whom demonstrated a Type 2 change. Of the variables tested in a multivariate analysis, age independently predicted lower area values for all 3 muscles (p ≤ 0.001), whereas female sex predicted a lower mean psoas area value (p < 0.001). None of the other variables significantly predicted any of the muscle area values. A decrease in the mean MF muscle area value alone was associated with a significantly increased likelihood of a PSC (p = 0.039).

CONCLUSIONS

Compared with normative controls, patients with IS suffer selective atrophy of their MF muscle, whereas their ES muscle undergoes a compensatory hypertrophy. Advancing age has a detrimental effect on the areas of the lumbar PSMs, whereas female sex predisposes to a decreased psoas muscle area. Multifidus muscle atrophy correlates with PSC, indicating the role of this deep stabilizer in the biomechanical stability of spondylolisthetic spines. This may be of clinical significance in targeted physiotherapy programs during the conservative management of IS.

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Sumit Thakar, Laxminadh Sivaraju, Kuruthukulangara S. Jacob, Aditya Atal Arun, Saritha Aryan, Dilip Mohan, Narayanam Anantha Sai Kiran and Alangar S. Hegde

OBJECTIVE

Although various predictors of postoperative outcome have been previously identified in patients with Chiari malformation Type I (CMI) with syringomyelia, there is no known algorithm for predicting a multifactorial outcome measure in this widely studied disorder. Using one of the largest preoperative variable arrays used so far in CMI research, the authors attempted to generate a formula for predicting postoperative outcome.

METHODS

Data from the clinical records of 82 symptomatic adult patients with CMI and altered hindbrain CSF flow who were managed with foramen magnum decompression, C-1 laminectomy, and duraplasty over an 8-year period were collected and analyzed. Various preoperative clinical and radiological variables in the 57 patients who formed the study cohort were assessed in a bivariate analysis to determine their ability to predict clinical outcome (as measured on the Chicago Chiari Outcome Scale [CCOS]) and the resolution of syrinx at the last follow-up. The variables that were significant in the bivariate analysis were further analyzed in a multiple linear regression analysis. Different regression models were tested, and the model with the best prediction of CCOS was identified and internally validated in a subcohort of 25 patients.

RESULTS

There was no correlation between CCOS score and syrinx resolution (p = 0.24) at a mean ± SD follow-up of 40.29 ± 10.36 months. Multiple linear regression analysis revealed that the presence of gait instability, obex position, and the M-line–fourth ventricle vertex (FVV) distance correlated with CCOS score, while the presence of motor deficits was associated with poor syrinx resolution (p ≤ 0.05). The algorithm generated from the regression model demonstrated good diagnostic accuracy (area under curve 0.81), with a score of more than 128 points demonstrating 100% specificity for clinical improvement (CCOS score of 11 or greater). The model had excellent reliability (κ = 0.85) and was validated with fair accuracy in the validation cohort (area under the curve 0.75).

CONCLUSIONS

The presence of gait imbalance and motor deficits independently predict worse clinical and radiological outcomes, respectively, after decompressive surgery for CMI with altered hindbrain CSF flow. Caudal displacement of the obex and a shorter M-line–FVV distance correlated with good CCOS scores, indicating that patients with a greater degree of hindbrain pathology respond better to surgery. The proposed points-based algorithm has good predictive value for postoperative multifactorial outcome in these patients.

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Sumit Thakar, Dilip Mohan, Sunil V. Furtado, Narayanam Anantha Sai Kiran, Ravi Dadlani, Saritha Aryan, Arun S. Rao and Alangar S. Hegde

Object

The objective of this study was to assess the cross-sectional areas (CSAs) of the superficial, deep flexor (DF), and deep extensor (DE) paraspinal muscles in patients with cervical spondylotic myelopathy (CSM), and to evaluate their correlations with functional status and sagittal spinal alignment changes following central corpectomy with fusion and plating.

Methods

In this retrospective study of 67 patients who underwent central corpectomy with fusion and plating for CSM, the CSAs of the paraspinal muscles were calculated on the preoperative T2-weighted axial MR images and computed as ratios with respect to the corresponding vertebral body areas (VBAs) and as flexor/extensor CSA ratios. These ratios were then compared with those in the normative population and analyzed with respect to various clinicoradiological factors, including pain status, Nurick grade, and segmental angle change at follow-up (SACF).

Results

The mean CSA values for all muscle groups and the DF/DE ratio were significantly lower in the study cohort compared with an age- and sex-matched normative study group (p < 0.001). Among various independent variables tested in a multivariate regression analysis, increasing age and female sex significantly predicted a lower total extensor CSA/VBA ratio (p < 0.001), while a longer duration of symptoms significantly predicted a greater total flexor/total extensor CSA ratio (p = 0.02). In patients undergoing single-level corpectomy, graft subsidence had a positive correlation with SACF in all patients (p < 0.05), irrespective of the preoperative segmental angle and curvature, while in patients undergoing 2-level corpectomy, graft subsidence demonstrated such a correlation only in the subgroup with lordotic curvatures (p = 0.02). Among the muscle area ratios, the DF/DE ratio demonstrated a negative correlation with SACF in the subgroup with preoperative straight or kyphotic segmental angles (p = 0.04 in the single corpectomy group, p = 0.01 in the 2-level corpectomy group). There was no correlation of any of the muscle ratios with change in Nurick grade.

Conclusions

Patients with CSM demonstrate significant atrophy in all the flexor and extensor paraspinal muscles, and also suffer a reduction in the protective effect of a strong DF/DE CSA ratio. Worsening of this ratio significantly correlates with greater segmental kyphotic change in some patients. A physiological mechanism based on DF dysfunction is discussed to elucidate these findings that have implications in preventive physiotherapy and rehabilitation of patients with CSM. Considering that the influence of a muscle ratio was significant only in patients with hypolordosis, a subgroup that is known to have facetal ligament laxity, it may also be postulated that ligamentous support supersedes the influence of paraspinal muscles on postoperative sagittal alignment in CSM.

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Narayanam Anantha Sai Kiran, Shashank Sharad Kale, Sandeep Vaishya, Manish Kumar Kasliwal, Aditya Gupta, Manish Singh Sharma, Bhavani Shankar Sharma and Ashok Kumar Mahapatra

Object

This retrospective study was designed to study the outcome in children with intracranial arteriovenous malformations (AVMs) treated with Gamma Knife surgery (GKS).

Methods

One hundred and forty-two children were treated with GKS at the authors' institution between April 1997 and March 2006; of these, 103 patients with a mean follow-up of 26.4 months (range 6–96 months) were included. The mean age at presentation was 13.9 years (range 3–18 years). Eighty-six (83%) patients presented with hemorrhage. In 57 children the AVMs were Spetzler–Martin Grade I or II, and in 46 the AVMs were Grades III, IV, or V. The mean volume of the AVMs was 2.4 ml (range 0.04–23.3 ml). The mean marginal dose administered was 24.4 Gy (range 15–27 Gy). Follow-up angiography was advised at 2 years after GKS and yearly thereafter. In patients with residual AVMs, follow-up angiography was advised yearly until 4 years after GKS. If residual AVM was present, even on a follow-up angiogram obtained 4 years postsurgery, the GKS was considered a failure.

Results

Complete obliteration of the AVM was documented in 34 (87%) of the 39 patients with complete angiographic follow-up. The 3- and 4-year actuarial rates of nidus obliteration were 66 and 86% respectively. Three patients (2.9%) experienced bleeding during the latency period, and symptomatic radiation-induced edema was noted in four patients (3.8%). A significantly higher incidence of radiation edema was noted in patients with AVM volumes greater than 3 ml and in patients with Spetzler–Martin Grade IV and V AVMs.

Conclusions

Gamma Knife radiosurgery is an effective modality for the treatment of intracranial AVMs in children, yielding high obliteration rates and low complication rates.

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Manish Kumar Kasliwal, Shashank Sharad Kale, Aditya Gupta, Narayanam Anantha Sai Kiran, Manish Singh Sharma, Bhawani Shanker Sharma and Ashok K. Mahapatra

Object

Although the effects of Gamma Knife surgery (GKS) on the risk of hemorrhage are poorly understood, a certain subset of patients does suffer bleeding after GKS. This study was undertaken to analyze the outcome of patients sustaining hemorrhage after GKS; it is the most feared complication of radiosurgical management of cerebral arteriovenous malformations (AVMs).

Methods

Between May 1997 and June 2006, 494 cerebral AVMs in 489 patients were treated using a Leksell Gamma Knife Model B, and follow-up evaluations were conducted until June 2007 at the All India Institute of Medical Sciences in New Delhi. Fourteen patients who sustained a hemorrhage after GKS formed the study group. In most of these patients conservative management was chosen.

Results

The mortality rate was 0% and there was a 7% risk of sustaining a severe deficit following rebleeding after GKS. None of the patients sustained rebleeding after complete obliteration. Patients with Spetzler-Martin Grade III or less had increased chances of hemorrhage after GKS (p < 0.002). The presence of deep venous drainage, aneurysm, venous hypertension, or periventricular location on angiography was common in patients with hemorrhage after GKS.

Conclusions

The risk of hemorrhage that remains following GKS for cerebral AVMs is highest in the 1st year after treatment. The present study showed a relatively good outcome even in cases with hemorrhage following GKS, with no deaths and minimal morbidity, further substantiating the safety and efficacy of the procedure.