Differentiation between Tuberculous and Pyogenic Spondylodiscitis: The Role of the Anterior Meningovertebral Ligament in Patients with Anterior Epidural Abscess.

BACKGROUND AND PURPOSE: Differentiation between tuberculous and pyogenic spondylodiscitis is a diagnostic challenge because imaging often does not reliably distinguish the 2 entities and percutaneous biopsies are often culture-negative. The purpose of this study was to determine whether violation of the anterior meningovertebral ligament in the setting of anterior epidural abscess discriminates between these entities. MATERIALS AND METHODS: This was a retrospective cohort study of all patients with acid-fast bacillus testing and anterior epidural abscess diagnosed on spinal MR imaging between May 2014 and September 2019, with a final diagnosis of tuberculous or pyogenic spondylodiscitis. Six cases of tuberculous spondylodiscitis (mean age, 45.5 years; 80% male) and 35 cases of pyogenic spondylodiscitis were evaluated (mean age, 56.6 years; 49% male). Demographic characteristics were recorded. Cases were assessed for anterior meningovertebral ligament destruction on MR imaging, as demonstrated by the shape of the epidural collection. Segmental location of the infection was also assessed. Independent 2-sample t tests and χ2 tests of independence were performed to evaluate the significance of the difference between the groups. RESULTS: Five of 6 (83.3%) cases of tuberculous epidural abscess had an intact anterior meningovertebral ligament, and 0/35 cases of pyogenic epidural abscess demonstrated an intact ligament (P < .001). The presence of an intact anterior meningovertebral ligament had 83.3% sensitivity and 100% specificity for tuberculous spondylodiscitis, a 100% positive predictive value, and a 97.2% negative predictive value. CONCLUSIONS: The presence of an intact anterior meningovertebral ligament has high sensitivity and specificity for tuberculous spondylodiscitis-associated epidural abscess, though these results should be validated in a larger sample.

Prevalence of hippocampal malrotation in a population without seizures.

BACKGROUND AND PURPOSE: Hippocampal malrotation (HIMAL) is a failure of hippocampal inversion that occurs during normal fetal development and has been seen on MR imaging examinations of people with epilepsy, but it has not been studied in patients without epilepsy. We intended to evaluate the prevalence of HIMAL in MR imaging examinations of patients without seizures to better understand the significance of HIMAL in the population with seizure. MATERIALS AND METHODS: A total of 497 MR imaging examinations with thin-section imaging through the temporal lobes of patients referred for conditions other than seizures were reviewed. The examinations were performed on 1.5T magnets. Sagittal T1-weighted and coronal T2-weighted images were used to evaluate each MR image for the distinctive features of HIMAL. As previously described in the literature, the criteria for HIMAL include unilateral involvement and incomplete rotation of a hippocampus that is normal in size and signal intensity but abnormally rounded in shape, with blurred inner structure. In addition, ipsilateral findings of an atypical collateral sulcus angle and atypical position and size of the fornix were noted. The corpus callosum is normal, and the temporal lobe remains normal in size, though the temporal horn may appear enlarged. RESULTS: None of the patients' examinations fulfilled all of the HIMAL criteria. Six studies satisfied 2 or more criteria, which included an abnormally rounded hippocampus and a vertical collateral sulcus. These HIMAL findings were all seen on the left. Forniceal asymmetry was the most prevalent abnormality, with 289 patients manifesting a low position of 1 fornix. CONCLUSIONS: Hippocampal malrotation is a rare finding in patients without seizures. HIMAL is therefore likely to be a pathologic finding.