Correlation between neurological recovery and magnetic resonance imaging in Pott's paraplegia

Spinal cord/nerve root compression secondary to a tubercular epidural abscess leads to neurological deficit. Depending on the extent and duration of compression, the end result after treatment may vary from complete recovery to permanent deficit. ASIA has been used extensively to correlate between MRI and neurological status due to traumatic spine injuries. MRI has stood as an invaluable diagnostic tool out of the entire range of current imaging modalities. However, inspite of considerable literature on the applications of MRI in spinal tuberculosis, there have been few studies to assess the relationship between the MRI findings and the neurological deficit as assessed by clinical examination.

The objective of this study was to ascertain whether the findings of magnetic resonance imaging (MRI) correlate well with the actual neurological recovery status using the American Spinal Injury Association impairment scale (ASIA) in patients with spinal compression secondary to tuberculous spondylitis.

60 patients (mean age 43.6 years) diagnosed as spinal tuberculosis by MRI/cytology/histopathology were examined and classified into ASIA impairment scale A-E based on the ASIA and again reclassified after 6 months of therapy to assess functional recovery. Similarly, they underwent MR imaging at the start and at the completion of 6 months of therapy to assess the structural recovery. The MRI features of recovery were correlated with the actual neurological recovery as ascertained by the ASIA.

Before starting treatment 1 patient (2.08%) was in ASIA A, 2 (4.16%) were in ASIA B, 9 (18.75%) were in ASIA C, 36 (75%) were in ASIA D and 12 (20%) were in ASIA E. There was a significant difference in the epidural abscess thickness, thecal compression and cord compression between ambulatory (ASIA D and ASIA E) and non ambulatory patients (ASIA A, ASIA B and ASIA C). After 6 months of therapy 30 (90%) patients in ASIA D and 5 (55.5%) in ASIA C had complete neurological recovery. Both patients from ASIA B improved to ASIA D. Single patient who was in ASIA A before treatment remained non ambulatory (ASIA C) after treatment. Overall 33 (78.5%) patients showed complete recovery at final followup. Out of all the MRI features, only size of epidural abscess was found to be a poor prognostic factor for recovery of neurological deficit.

There are several parameters on MRI which correlate with the severity of neurological impairment according to ASIA score and resolution of those features on treatment is also correlated well with neurological recovery.