Magnetic resonance imaging ( MRI) of thoracolumbar spine with gadolinium (Figures 1A, 1B) showed an expansive lesion, with affectation of the distal medullary cone, isointense to spinal cord on T1, heterogeneous intensity, and areas of hyperintensity on T2.
Surgical exploration was conducted of the medullary cone, finding a thickened and hardened epiconus, with arachnoid and healthy skin, a tough avascular intra-axial fibrous lesion, from which samples were taken.
The medullary segments evaluated were the cervical (CS), thoracic (TS), lumbar (LS), and sacrocaudal (SCS) segments and the medullary cone (CM).
The funneling of the lumbar segment of the spinal cord originates in the medullary cone (ERHART, 1992; GETTY et al., 1986; GODINHO et al., 1987), which begins between L5 and L6 in Equus caballus and Chrysocium brachiurus (MACHADO et al., 2002), between L6 and L7 in Oryctolagus cuniculus (SANTOS et al., 1999), in L5 of Arctocephalus australis (MACHADO et al., 2003), L6 of Herpailurus yagouaroundi (CARVALHO et al., 2003) and Felis catus (CAMARA-FILHO et al., 1998), varies between L5 and L7 in pacas (SCAVONE et al., 2007) and between L2 and L6 in M.
The apex of the medullary cone occurs between the fifth or sixth lumbar vertebra in pigs, between the sixth or seventh lumbar vertebra in dogs, the second sacral vertebra in horses, and more variably between the sixth lumbar and third sacral vertebrae in cats (DYCE et al., 2004).
The reported lengths of the medullary cone are 100 mm in horses, 45.1 mm in rabbits (SANTOS et al., 1999), 88.5 mm in sheep (SANTOS et al., 1999); and 33.9 mm in Agouti paca (SCAVONE et al., 2007).
T2*-weighted and T2-weighted magnetic resonance imaging (MRI) showed intramedullary bleeding in the central portion of the medullary cone (Figures 1 and 2).
The reason for the patient's complaints was postpuncture intramedullary bleeding in the medullary cone. MRI, especially T2*-weighted GRE imaging, can be very useful in detecting the smallest amounts of intramedullary bleeding (2) because of the paramagnetic effect of iron that is contained in hemoglobin (Figure 1).
