Correlation of diffusion tensor imaging parameters with neural status in Pott's spine.

INTRODUCTION: Diffusion tensor imaging (DTI) has been used in cervical trauma and spondylotic myelopathy, and it has been found to correlate with neural deficit and prognosticate neural recovery. Such a correlation has not been studied in Pott's spine with paraplegia. Hence, this prospective study has been used to find correlation of DTI parameters with neural deficit in these patients. METHODS: Thirty-four patients of spinal TB were enrolled and DTI was performed before the start of treatment and after six months. Fractional anisotropy (FA), Mean diffusivity (MD), and Tractography were studied. Neurological deficit was graded by the Jain and Sinha scoring. Changes in FA and MD at and below the site of lesion (SOL) were compared to above the SOL (control) using the unpaired t-test. Pre-treatment and post-treatment values were also compared using the paired t-test. Correlation of DTI parameters with neurological score was done by Pearson's correlation. Subjective assessment of Tractography images was done. RESULTS: Mean average FA was not significantly decreased at the SOL in patients with paraplegia as compared to control. After six months of treatment, a significant decrease (p = 0.02) in mean average FA at the SOL compared to pre-treatment was seen. Moderate positive correlation (r = 0.49) between mean average FA and neural score after six months of treatment was found. Tractography images were not consistent with severity of paraplegia. CONCLUSION: Unlike spondylotic myelopathy and trauma, epidural collection and its organized inflammatory tissue in Pott's spine precludes accurate assessment of diffusion characteristics of the compressed cord.

Diffusion tensor imaging observation in Pott's spine with or without neurological deficit.

BACKGROUND: Diffusion tensor imaging (DTI) is based upon the phenomenon of water diffusion known as "Brownian motion." DTI can detect changes in compressed spinal cord earlier than magnetic resonance imaging and is more sensitive to subtle pathological changes of the spinal cord. DTI observation in compressed and noncompressed spinal cord in tuberculosis (TB) spine is not described. This study presents observations in Pott's spine patients with or without neural deficit. MATERIALS AND METHODS: Thirty consecutive cases of TB spine with mean age of 32.1 years of either sexes with paradiscal lesion, with/without paraplegia divided into two groups: Group A: (n = 15) without paraplegia and group B: (n = 15) with paraplegia were evaluated by DTI. The average fractional anisotropy (FA) and mean diffusivity (MD) values were calculated at 3 different sites, above the lesion (SOL)/normal, at the lesion and below SOL for both groups and mean was compared. Visual impression of tractography was done to document changes in spinal tracts. RESULTS: The mean canal encroachment in group A was 39.60% and group B 44.4% (insignificant). Group A mean FA values above SOL, at the lesion and below SOL were 0.608 ± 0.09, 0.554 ± 0.14, and 0.501 ± 0.16 respectively. For group B mean FA values above SOL, at the lesion and below SOL were 0.628 ± 0.09, 0.614 ± 0.12 and 0.487 ± 0.15 respectively. There was a significant difference in mean FA above the SOL as compared to the mean FA at and below SOL. P value above versus below the SOL was statistically significant for both groups (0.04), but P value for at versus below the SOL (0.01) was statistically significant only in group B. On tractography, disruption of fiber tract at SOL was found in 14/15 (93.3%) cases of group A and 14/15 cases (93.3%) of group B (6/6 grade 4, 3/3 grade 3 and 5/6 grade 2 paraplegic cases). CONCLUSION: The FA and MD above the lesion were same as reported for healthy volunteer hence can be taken as control. FA increases, and MD decreases at SOL in severe grade of paraplegia because of epidural collection while in milder grade, both decrease. In group A (without neurological deficit), mean FA and MD in patients with and without canal encroachment was similar. On tractography, both groups A and B (with or without neurological deficit) showed disruption of fiber tract at SOL and thickness of distally traced spinal cord was appreciably less than the upper cord. FA and MD could not differentiate between various grades of paraplegia. Although the number of patients in each group are small.

Tuberculosis spine: Therapeutically refractory disease.

BACKGROUND: India ranks second amongst the high-burden multi drug resistant tuberculosis (MDR-TB) countries, with an estimated incidence of 2.3% MDR-TB cases amongst the new cases and 17.2% amongst the previously treated cases. The diagnosis and treatment protocol for MDR-TB of the spine are not clearly established. We report outcome of a series of 15 cases of TB spine who were suspected to be therapeutically refractory cases (MDR-TB) on the basis of clinicoradiological failures of initial treatment. MATERIALS AND METHODS: Fifteen cases of TB spine from C2 to L5 spine were suspected to be the cases of MDR-TB (therapeutically refractory cases) on the basis of failures of adequate clinicoradiological healing response at 5 months or more on antitubercular treatment (ATT). None of the patient was immunocompromised. Thirteen out of 15 patients had tissue samples sent for histopathology, culture and sensitivity, smear, BACTEC, and polymerase chain reaction (PCR). All patients were put on second line ATT and followed up fortnightly with regular liver and kidney function tests, erythrocyte sedimentation rate (ESR), and plain X-ray. Healing was documented as subjective improvement of symptoms, reduction in ESR, and observations on contrast enhanced magnetic resonance imaging (MRI) such as resolution of marrow edema, fatty replacement of bone marrow and resolution of abscesses. Ambiguous MRI observations in a few patients were resolved on positron emission tomography (PET) scan. Patients were monitored continuously for 2 years after stopping ATT. RESULTS: We could demonstrate a positive culture in three cases. Two of them had multi drug resistance. We could achieve healing status in 13 out of 14 patients after starting second line drugs, one patient is still on treatment while other patient with no drug resistance is responding well on ATT. CONCLUSIONS: The suspicion of therapeutically refractory case is of paramount importance. Once suspected, surgery to procure tissue for diagnosis and culture is to be undertaken. The demonstration of drug resistance on culture may not be achieved in all TB spine cases and empiric drug regimen for MDR-TB is to be started. We have achieved the healed status with immunomodulation and second line ATT. The length of treatment needs to be monitored with MRI and PET scan.

Efficacy of extended DOTS category I chemotherapy in spinal tuberculosis based on MRI-based healed status.

BACKGROUND: Duration of treatment in tuberculosis of spine has always been debatable in the absence of marker of healing. The objective of the study was to evaluate the efficacy of extended DOTS regimen (2 months of intensive phase and 6 months of continuation phase) as recommended by WHO, by using MRI observations as the healing marker. MATERIALS AND METHODS: 51 (Group A -28 prospective and Group B- 23 retrospective) patients of spine TB with mean age of 26.8 years (range 15-54 years) diagnosed clinico radiologically/imaging (n=36), histopathology or by PCR (n=15) were enrolled for the study. They were treated by extended DOTS regimen (2 months of HRZE and 6 months of HR) administered alternate day. The serial blood investigations and X-rays were done every 2 months. Contrast MRI was done at the end of 8 months and healing changes were recorded. Criteria of healing on the basis of MRI being: complete resolution of pre and paravertebral collections, resolution of marrow edema of vertebral body (VB), replacement of marrow edema by fat or by calcification suggested by iso- intense T1 and T2 weighted images in contrast enhanced MRI. Patients with non healed status, but, responding lesion on MRI after 8 months of treatment were continued on INH and rifampicin alternate day and contrast MRI was done subsequently at 12 months and 18 months till the healed status was achieved . RESULTS: 9 patients had paraplegia and required surgical intervention out of which 1 did not recover neurologically. All patients have completed 8 months of extended DOTS regimen, n=18 achieved healed status and duration of treatment was extended in rest (n=33) 5 were declared healed after 12 months, 8 after 18 months and one after 36 months of treatment, thus 32 were declared healed at varying periods. CONCLUSION: 35.2% patients demonstrate MRI based healed vertebral lesion at the end of 8 months of extended category 1 DOTS regimen. It is unscientific to stop the ATT by fixed time frame and MRI evaluation of the patients is required after 8 months of ATT and subsequently to decide for the continuation stoppage of treatment.

Magnetic resonance evaluation of tubercular lesion in spine.

PURPOSE: Information on Magnetic Resonance (MR) features of active and healed lesions in tuberculosis (TB) spine are lacking. We evaluated MRI findings in active and healed proven TB spine to establish the diagnostic features. MATERIALS AND METHOD: Forty-nine consecutive spinal TB patients (20 male; 29 female) diagnosed clinicoradiologically and/or on histopathology, Fine Needle Aspiration Cytology (FNAC), bacteriology, or Polymerase Chain Reaction (PCR) were enrolled. Pretreatment MR scans were reviewed for diagnostic features, and eight-month follow-up MR scans were reviewed for healing changes. RESULTS: Cervical spine (n = 6), dorsal spine (n = 14), and lumbar spine (n = 29) were affected. Fourteen had paraplegia. Mean vertebrae involved were 2.61 on X-ray with a total of 128 vertebrae (VB) and 3.2 on MRI (range, 2-15) with 161 VB. The lesions were more extensive on MRI (34.7%) than appreciated on X-ray. The disc was preserved partially or fully in 88.2% of instances. End plate erosions (159/161 VB), lost VB height (94/161), exudative lesion (158/161), granular lesion (3/161), pre and paravertebral collections (49/49 cases), marrow oedema (161/161), discitis (98%), epidural involvement (107/161), epidural spread (100/161), and subligamentous spread (156/161) were observed. Canal encroachment (10-90%) was seen in 37 cases. Mean motor and sensory scores with greater than 50% canal encroachment were 87/100 and 156/168, respectively. Cord oedema was observed in 11 cases (eight with neural deficit and three cases without). Cord atrophy was seen in one case each before and after treatment. A total of 83% of patients had a combination of paravertebral collections, marrow oedema, subligamentous and epidural extension, endplate erosions and discitis. On healing (n = 20), complete resolution of marrow oedema and collections, fatty replacement of bone marrow and resolution of cord signal intensity were observed. CONCLUSION: The marrow oedema, preservation of disc space, subligamentous extension of abscess, septate paravertebral abscess, epidural extension, endplate erosions and discitis were consistently observed in 83% cases of TB spine on MRI.