Organization of intrathecal nerve roots at the level of the conus medullaris.

Wall, Eric J.; Cohen, Mark S.; Abitbol, Jean Jacques; Garfin, Steven R.

doi:10.2106/00004623-199072100-00010

Cited by 63 publications

(41 citation statements)

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“…(A)`Standard geometry' as used for the simulation. The arrangement of the spinal cord segments is constructed from spinal root ®ber identi®cation in four cross sections as reported by Wall et al 15 : it is assumed that segments with ®bers which are passing the observed cross-section are located completely above this cross section level. (B) Spinal cord geometry derived from Lang and Geisel data.…”

Section: Discussionmentioning

confidence: 99%

“…This model is valid under the assumption that the potential distribution in the cerebrospinal¯uid surrounding the rootlets is not aected by the presence of these ®laments. Note however that the lower part of the lumbar cord is surrounded by roots and the cord becomes completely covered by the roots below the twelfth thoracic vertebra 15 (see also the cross sections at the left part of Figure 10). Therefore, a re®ned model including the insulating property of the roots is assumed to show increase of threshold values for ventral roots and dorsal columns when the electrode is moved to the conus medullaris.…”

Section: Discussionmentioning

confidence: 99%

“…Our assumptions about a`standard' shape of the spinal cord, its relative position to the vertebral bone, the trajectory of the rootlets and the other geometrical parameters of the body are based on the ®ndings of Wall et al, 15 Kameyama et al 16 and on the`Body Explorer', 17 an interactive program on the crosssectional anatomy of the`Visible Human Male', with small modi®cations according to X-ray and MRI data of our patients (Figure 1). The electrical conductivities of the biological materials are listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

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Epidural electrical stimulation of posterior structures of the human lumbosacral cord: 2. quantitative analysis by computer modeling

2000

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Objectives: Analysis of the computed recruitment order of an ensemble of ventral and dorsal root ®bers should enlighten the relation between the position of a bipolar electrode and the observed order of muscle twitches. Material and methods: Thresholds of selected spinal root ®bers are investigated in a two step procedure. First the electric ®eld generated by the electrodes is computed with the Finite Element Method. In the second step the calculated voltage pro®le along each target neuron is used as input data for a cable model. For every electrode position the electrical excitability is analyzed for 12 large diameter ventral and dorsal root ®bers of the second and fourth lumbar and ®rst sacral segment. The predictions of the neural responses of any target ®ber are based on the activating function concept and on the more accurate computer simulations of the electrical behavior of all nodes and internodes in the vicinity of the electrode.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Epidural electrical stimulation of posterior structures of the human lumbosacral cord: 2. quantitative analysis by computer modeling

2000

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“…18 A number of spinal ®bers attached to a shallow depression in the posterolateral sulcus fuse to form a dorsal nerve root structure. 19,20 In a similar way, small ®bers fuse along the anterior aspect of the spinal cord to form a ventral root. Before they form the nerve root, however, the sensory and motor ®bers are distinct entities to lateral sac.…”

Section: Discussionmentioning

confidence: 99%

Epidural electric stimulation of posterior structures of the human lumbar spinal cord: 1. muscle twitches – a functional method to define the site of stimulation

Murg¹,

Binder

2000

Spinal Cord

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Objectives: To describe an electrophysiological method for determining the relation between lumbar cord dorsal roots and cathode of epidural electrode for spinal cord stimulation (SCS). Materials and methods: Data has been collected from 13 subjects who have been under evaluation of eectiveness of SCS for control of spasticity. Induced muscle twitches from both quadriceps (Q), adductors (A), hamstrings (H), tibial anterior muscles (TA) and triceps surae muscles (TS) were simultaneously recorded with surface-electrode polyelectromyography (pEMG) and analyzed for amplitudes, latency times and recruitment order. Results: Stimulation of dorsal lumbar cord structures evoked characteristic EMG events during muscle twitch responses. Their amplitudes varied with stimulus strength. Latency times were rather invariable regardless of stimulus strength. Two distinct recruitment orders were demonstrated depending on whether the stimulating cathode was placed over the upper (=response from quadriceps and/or adductor muscles) or the lower (=response from tibialis anterior and triceps surae) lumbar cord segments. The chances to stimulate upper lumbar cord segments are best around the 12th thoracic vertebra. Conclusions: pEMG recording of muscle twitches enables us to accurately dierentiate between upper and lower lumbar cord segments. Furthermore, our ®ndings regarding amplitude, latency and recruitment order strongly suggest that we stimulate posterior roots not posterior columns of the lumbar spinal cord. Spinal Cord (2000) 38, 394 ± 402

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“…8) All intradural roots follow highly organized overlapping patterns from the lumbar enlargement to conus medullaris. 5,14) In these patterns, the most rostral roots lie laterally, and the more caudal roots overlap toward the midline. Therefore, central cord compression due to disk herniation, osteophyte, or tumor at the T10-11 or T11-12 intervertebral level is sufficient to create sciatica-like pain.…”

Section: Discussionmentioning

confidence: 99%

Thoracic Disk Herniation Manifesting as Sciatica-Like Pain -Two Case Reports-

Cho

Lee

Kim

2011

Neurol. Med. Chir.(Tokyo)

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Fig. 1 Case 1. Sagittal T 2 -weighted magnetic resonance image revealing multilevel lumbar bulging disks, degeneration, and high intensity zones at L3-4 and L4-5 disks. AbstractTwo patients presented with sciatica-like pain caused by thoracic disk herniation. Sciatica-like pain was the initial and major symptom in both patients, but careful neurological examination showed vague signs of upper motor neuron disturbance, and thoracic magnetic resonance (MR) imaging revealed disk herniations at the mid-thoracic level. After video-assisted thoracoscopic discectomy, the pain was completely improved. Thorough neurological examination and MR imagery of the thoracic spine, and if needed, even the cervical spine, are required if lumbar image findings do not correlate with the symptoms or physical examination.

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Organization of intrathecal nerve roots at the level of the conus medullaris.

Cited by 63 publications

References 0 publications

Epidural electrical stimulation of posterior structures of the human lumbosacral cord: 2. quantitative analysis by computer modeling

Epidural electrical stimulation of posterior structures of the human lumbosacral cord: 2. quantitative analysis by computer modeling

Epidural electric stimulation of posterior structures of the human lumbar spinal cord: 1. muscle twitches – a functional method to define the site of stimulation

Thoracic Disk Herniation Manifesting as Sciatica-Like Pain -Two Case Reports-

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