LUMBAR MRI IN PRONE POSITION and minimally invasive surgery of SECTION FILUM TERMINALE EXTERNUM (EXTRADURAL) under local anaesthesia in the OCCULT TETHERED CORD
In 2020 were published in the scientific journal Pediatric Neurosurgery our innovative protocol. It involves the association between lumbar MRI in the prone position and minimally invasive surgery of the filum terminale extradural (externum) section under local anaesthesia.
We described this protocol for the first time in the international medical scientific literature.
The patients operated with this protocol are generally adult patients, and to date, they are over 200, the 4 adolescent patients operated on have been the subject of the aforementioned scientific work. In adult patients, the occult tethered cord can present itself as the only pathology or association with the presence of the tonsils slightly descended cerebellar, 0-4 mm (LLCT), or Chiari malformation.
LUMBAR MR IN PRONE POSITION
IN OCCULT TETHERED CORD
This 2013 scientific work was published in an international medical journal by Japanese colleagues from the University of Hiroshima.
Magnetic resonance imaging in a prone position was used to identify the abnormal position of the filum at the lumbar intradural level in patients with occult tethered cord syndrome. Japanese colleagues compared a group of patients with occult tethered cord syndrome with a group of people asymptomatic.
Magnetic resonance imaging in the prone position showed a significant difference in the position of the filum terminale between the two groups. In patients with occult tethered cord syndrome the filum terminale was not carried by gravity anteriorly with the nerve rootlets but remained in the posterior position (SEE FIGURE IN HIGH RIGHT, figure on the right).
In the lumbar MRI in the prone position, if the filum terminale is not under tension, it does not locate posteriorly and does not differ from the position of the nerve roots and cannot be the cause of disorders presented by the patient. The finding of the posterior position of the filum terminale cannot evaluate the intrinsic elasticity of the filum terminale itself but a stretched filum terminale can traction the spinal cord to which it is connected causing the disturbances that are found in the occult tethered cord syndrome. It is part of the clinical-instrumental protocol adopted for our patients. Magnetic resonance in the prone position allows to support the clinical-anamnestic data. At present there are no other instrumental tests that can give this type of information. This reduces the risk of placing surgical indications in patients with symptoms which, being generic and non-specific, may be due to other pathological situations.
IMAGE ON TOP LEFT. Abstract of the scientific work published in the Neurosurgical Journal Spine 2013.
IMAGE ON TOP RIGHT. Axial images of the lumbar magnetic resonance imaging in a prone position to evaluate the position of the filum terminale intradural:
- on the left: images of a healthy person in the control group;
- on the right: images of a patient with occult tethered cord syndrome. In patients with occul tethered cord syndrome the filum terminale does not move anteriorly with the nerve roots but remains in the posterior position (WHITE ARROW HEAD).
LUMBAR MR IN PRONE POSITION
IN TETHERED CORD
In 2018, American Colleagues from the University of Chicago carried out a study to evaluate the usefulness of lumbar MRI in a prone position in the cases of TETHERED CORD and in RIANCORAGGIO MIDOLLARE.
They also evaluated a small group of patients with OCCULT TETHERED CORD who are not part of the case analysis. American colleagues in evaluating the percentage of movement of the spinal cone in the supine and prone position conclude their work by stating that: "In the present series, MRI in the prone position proves to be a sensitive and specific tool and the authors believe it may have a role as evidence of support in the diagnosis of anchored marrow or spinal cord rearrangement. " IMAGE ON TOP LEFT: - Abstract of the scientific work published in the Journal Neurosurg Pediatrics 2018. IMAGE ON TOP RIGHT. Images relating to the evaluation of the percentage of mobility of the medullary cone (ventral conus motion): - On the left an example of how the aforementioned mobility of the medullary cone is calculated. - On the right a negative test in which there is a wide mobility of the medullary cone not compatible with the presence of tethered cord.