Bilateral meningiomatous lesions of the spinal accessory nerves.

BACKGROUND: Meningiomas arising from cranial nerves with no dural attachment are exceedingly rare. The authors present a patient with bilateral meningiomatous lesions originating symmetrically from both spinal accessory nerves. CASE REPORT: A 61-year old woman presented with a one-year history of spinal ataxia and minimal left-sided motor impairment. Magnetic resonance imaging demonstrated two extrinsic lesions dorsolaterally of the medulla. Surgical exposure via a midline suboccipital approach with C1 laminectomy revealed the lesions arising from the spinal accessory nerves and in direct contact with the vertebral arteries. Histological investigation showed hypocellular fibrous lesions with proliferating meningothelial cells, psammoma bodies and immunoreactivity for vimentin, S-100 protein and epithelial membrane antigen. INTERPRETATION: To the authors' knowledge this is the first report of intradural tumours of the spinal accessory nerves not derived from Schwann cells and the first report of bilateral intracranial meningiomatous lesions without dural attachment.

Isochromosome 1q as an early genetic event in a child with intracranial ependymoma characterized by molecular cytogenetics.

Data concerning cytogenetic features of childhood ependymoma are rare. In this article, a gain of 1q was identified as the sole alteration in a primary childhood infratentorial ependymoma by comparative genomic hybridization (CGH). A recurrence of this brain tumor was studied using multiplex-fluorescence in situ hybridization (M-FISH) in addition to CGH and G-banding analysis. In accordance with the primary tumor, a gain of 1q corresponding to an isochromosome 1q was observed indicating an early event in the tumor development. Furthermore, M-FISH classified several other rearranged chromosomes including 6q and 17p that have previously been found to be involved in the development and progression of childhood ependymoma.

Tailored laminectomy: a new technique for neuromodulator implantation.

PURPOSE: Neuromodulation of sacral roots is an alternative mode of therapy for patients with urge incontinence or detrusor hypocontractility. We investigated the effects of sacral (S3) nerve stimulation in patients using a new surgical approach for sacral neuromodulator implantation. Modification of the implantation method with sacral laminectomy and bilateral electrode placement led to distinct improvement of stimulation, positioning and dislocation. We developed tailored laminectomy for bilateral neuromodulator electrode implantation to minimize surgical trauma. MATERIALS AND METHODS: Tailored laminectomy was performed in 6 patients with urge incontinence and 3 with a hypocontractile detrusor. After making a 10 cm. longitudinal skin incision we exposed the spinous processes of S2 and S3. Instead of complete 2-level laminectomy, only 2 oval laminectomy holes were made with a high speed ball drill. An electrode fixation hole was drilled at the edge of the laminectomy window and the wire was fixed with nonabsorbable suture material. RESULTS: In patients with idiopathic urge incontinence (followup 12.5 months, range 7 to 18) the number of leaks decreased from 7.2 to 0 daily and functional bladder capacity increased from 298 to 352 ml. In patients with a hypocontractile detrusor (followup 10.5 months, range 6 to 20) detrusor pressure increased during voiding from 12 to 34 cm. water and post-void residual decreased from 350 to 58 ml. Average surgery time was 2 hours 15 minutes. In 1 case a seroma developed near the impulse generator. CONCLUSIONS: Tailored laminectomy is a fast, minimally invasive and reliable technique for neuromodulator implantation.

Cerebral potentials preceding voluntary toe, knee and hip movements and their vectors in human precentral gyrus.

In this study, the brain potentials related to voluntary, self-paced plantarflexions of the left toes, flexion of the right knee and isometric extensions of the left hip were examined in 3 groups of 10 subjects each. In the first half of the foreperiod, the Bereitschaftspotential (BP) or readiness potential for all movements was symmetrically distributed over both hemispheres. For toe and knee movements, an ipsilateral preponderance of the BP developed in the later foreperiod, which was statistically significant for toe movements. For hip movements, BP topography was symmetrical during the entire foreperiod including its second half. Since finger, hand or shoulder movements of previous experiments show a strong contralateral preponderance of the BP, the results are discussed as further support of the hypothesis that the lateralisation of the BP is due to the orientation of the precentral electrical field vector generated by an active source in the MI motor cortex. Thus, part of the somatotopic representation of the human precentral gyrus can be mapped by this non-invasive means: upper limb movements are located on the convexity; toe, foot and knee movements are generated on the mesial cortex between the hemispheres; and hip movements seem to be located at the mantle edge.

Handedness, footedness and finger and toe movement-related cerebral potentials.

Sixteen right-handed and 16 left-handed subjects were compared with respect to their foot dominance and the topography of their pre-movement cerebral potentials (Bereitschaftspotential, BP). First, righthanders were usually also found to be right-footed. Lefthanders showed a similar trend in preferring their left foot. Second, the BP prior to volitional self-paced movements of fingers and toes on either side was examined. For finger movements, the BP always showed higher amplitudes over the contralateral hemisphere as compared to the ipsilateral one (contralateral preponderance of negativity, CPN). For toe movements a significant ipsilateral preponderance of negativity (IPN) occurred in all subjects. The CPN was larger for finger movements of the dominant hand than it was for finger movements on the non-dominant side. By contrast, the IPN was larger prior to movements of the "non-dominant toes" than it was for movements of the dominant toes. This can be explained by assuming that the hemisphere contralateral to the dominant hand, generates more negativity than the one contralateral to the non-dominant hand. This assumption is further discussed in the context of a vector model for the BP.

Movement-related potentials preceding toe plantarflexion and dorsiflexion.

The cerebral potentials associated with self-paced rapid dorsiflexion and plantarflexion of the left toes were compared in the same experiment using 10 subjects 5 of whom were female and 5 of whom were male. The EEG was recorded from C3, C1, Cz, C2 and C4 including computed bipolar recordings C4/C3 and C2/C1. For both kinds of movements, the Bereitschaftspotential (BP) or readiness potential was bilaterally symmetrical in the first half of the foreperiod. In the later foreperiod, an ipsilateral preponderance of negativity (IPN) developed. The direction of toe movement had no effect on the IPN. The etiology of the paradoxical BP side preponderance prior to toe movements is discussed which can probably be referred to the unique dipole orientation of a generator situated on the mesial cortical surface in the depth of the interhemispherical fissure.

Finger movement versus toe movement-related potentials: further evidence for supplementary motor area (SMA) participation prior to voluntary action.

The cerebral potentials associated with voluntary, self-paced rapid flexions of (1) right fingers, (2) left fingers, (3) right toes, and (4) left toes were compared in the same experiment using 32 right- and left-handed subjects. The Bereitschaftspotential (BP) or readiness potential was, in the first half of the foreperiod, bilaterally symmetrical for both finger and toe movements of either side. In the later foreperiod there were differences: Finger movements showed two maxima, an early one at Cz and a late one, which was lateralized toward the contralateral precentral region. With toe movements, the maximum BP amplitude was always at Cz and not lateralized and was twice as large as with finger movements. The data are compatible with the view that two principal sources of different spatial and temporal characteristics are active in the foreperiod of a voluntary movement. The early generator is probably the supplementary motor area (SMA) on the mesial surface of the hemispheres; the later is the primary motor cortex (MI) which is lateralized for finger but not for toe movements. In lateral leads, rather remote from the mesial source, the BP for toe movements showed a small but significant ipsilateral preponderance, which is obviously due to the fact that dipole sources located on the mesial surface of the hemispheres point to the opposite direction as compared to those on the convexity.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnetic fields of the human brain (Bereitschaftsmagnetfeld) preceding voluntary foot and toe movements.

Voluntary movements are preceded by a slow electrical potential of the brain (Bereitschafts-potential, BP) or readiness potential. The BP is accompanied by a magnetic field shift of similar time characteristics (Bereitschaftsmagnetfeld, BM). The BM preceding volitional right foot or toe movements was recorded from anterior, posterior, and lateral positions of the scalp using a SQUID (Superconducting Quantum Interference Device) third-order gradiometer. Controls were implemented to reduce head movements, which were simultaneously recorded with a mechanograph. The results showed that movements of the lower extremities are also preceded by a BM. However, contrary to finger movements, BMs with field lines directed into the head were found predominantly for foot movements and exclusively for toe movements. The BM preceding foot movements was maximum over a position 2 cm left of the vertex, i.e., contralateral to the movement. Two centimeters right of the vertex it was smaller, thus exhibiting a normal contralateral preponderance and not sharing the paradoxical side preponderance of the electrical BP preceding foot or toe movements. The BM preceding toe movements was only apparent at the vertex and was smaller than the one preceding foot movement. This may suggest a source that is located still deeper in the brain than with foot movements.