Limited benefit of electrophysiological studies during dorsal rhizotomy

Using a formula for standard deviation and several assumptions, the potential benefit of electrophysiological recording (ER) during dorsal rhizotomy for cerebral palsy is calculated and expressed in a ratio, the electrophysiological recording benefit ratio (ERBR). ERBR is approximately 1.1 in most of the examples, but other factors may reduce this ratio. Severing an additional rootlet appears to be a viable alternative to ER in most of the examples. Advantages of dorsal rhizotomy without ER include reduced expense and operative time. Prospective studies are recommended to evaluate further the benefit of ER during dorsal rhizotomy. If stimulation of dorsal rootlets is abandoned during dorsal rhizotomy, stimulation of whole dorsal and ventral roots may still be necessary to prevent inadvertent severing of motor fibers. © 1994 John & Sons, Inc.     

Progression despite replacement of a myopathic form of coenzyme Q10 defect

The authors report 7 years of follow-up evaluation of a patient with coenzyme Q10 (CoQ10) deficiency. Initial symptoms of exercise intolerance and hyperlactatemia improved markedly with substitutive treatment. However, CoQ(10) supplementation did not prevent the onset of a cerebellar syndrome. A switch to idebenone treatment resulted in clinical and metabolic worsening, which disappeared with subsequent CoQ10 treatment. CoQ10 defects may cause progressive neurologic disease despite supplementation.     

Relationship of early neural tube appearance to myeloschisis in a chick embryo model

Myeloschisis, a form of neural tube defect involving the spinal cord, was induced in chicks by creating a window in the eggshell of the fertilized egg at 26 h after placement in an incubator. The embryos were stained and photographed through the window at 48 to 60 h after commencement of incubation and the neural tube was determined to be normal, delayed, irregular, or abnormally open for the developmental stage of the embryo. The eggs were then reincubated until 14 days of age. At that time the chicks were determined to have normal spinal cords or myeloschisis by gross examination, dissection, and histology. The appearance of the neural tube at 48 to 60 h was then correlated with the appearance of the spinal cord at 14 days of age. It was determined that in the chick embryo model of myeloschisis induced by windowing, a normal neural tube at the time of neural tube closure results in a 2.3% incidence of myeloschisis, a widely open neural tube a 47% incidence of myeloschisis, an irregular neural tube a 37% incidence of myeloschisis, and delayed closure of the neural tube a 14% incidence of myeloschisis. Thus, no appearance of an early neural tube can be said to always correlate with myeloschisis or a normal outcome. Additionally, it appears that within a single model there may be multiple mechanisms of production of myeloschisis.     

The leptomeningeal form of primary neuroectodermal tumor

Brain neoplasms as primary leptomeningeal forms are rare, particularly if the case in point is primary neuroectodermal tumors (PNET). In the literature, there are only few reports on this topic. The authors describe one of such rare cases. A 21-years-old man was admitted to a hospital for complaints about headache. Brain computed tomography and magnetic resonance imaging (MRI) revealed internal hydrocephalus and slightly uniform meningeal thickening without the signs of space-occupying lesions. Ten months after ventriculoperitoneostomy, the patient suddenly developed tetraparesis and respiratory disorders. MRI showed a pronounced diffuse non-uniform leptomeningeal dissemination of a tumor. Open biopsy of the lesion in the projection of the right fissure detected PNET. The patient underwent a course of chemotherapy (CCNU, vincristine) and radiotherapy (total focal dose 45 Gy). Control MRI could not identify a pathological leptomeningeal signal.     

Microsurgical analyses of avian neurulation: separation of medial and lateral tissues

Neurulation, formation of the neural tube, is a complex process involving shaping and bending of the neural plate and closure of the neural groove. We have used avian embryos as model systems to study this process. In the present investigation, blastoderms were cut parasagittally through their entire thickness, either unilaterally or bilaterally, at two mediolateral locations: 1) at the juncture between prospective neural plate and prospective surface epithelium, and 2) at the juncture between the midline strip of prospective neural plate and more lateral prospective neural plate. In the first experiment, shaping of the neural plate seemed normal, but elevation and convergence of the neural folds and closure of the neural groove were inhibited (except at the forebrain level). This result demonstrates that extrinsic forces generated by lateral tissues are required for neural plate bending and neural groove closure. In the second experiment, neuroepithelial cells within the isolated, midline strip became wedge shaped. This result indicates that neuroepithelial cell "wedging" is an active event occurring independently of forces generated by elevation of the neural folds. Additional studies are required to define the natures of neurulation forces and the mechanisms by which they are generated.     

A disorder of colour perception associated with abnormal colour after-images: a defect of the primary visual cortex

A 64 year old woman with posterior cortical atrophy secondary to probable Alzheimer's disease is described. Her presenting symptom was of seeing objects as abnormally coloured after prior exposure to a coloured stimulus. Formal testing disclosed that the patient experienced colour after-images of abnormal latency, duration, and amplitude.The demonstration of prolonged colour after-images in a patient with a cortical disease process provides strong evidence that the generation of colour after-images is mediated at least in part by the visual cortex. A mechanism for the generation of colour after-images is proposed in which abnormal prolongation of the images results from excessive rebound inhibition of previously excited wavelength selective neurons in V1. This may occur as a consequence of the relative sparing of inhibitory interneurons in V1 in the context of the degeneration of excitatory neurons that occurs in Alzheimer's disease.     

Osteoblastoma of dorsal spine: a case report

A case of benign osteoblastoma affecting posterior element of spine with pain and paraplegia in a female is being presented with brief review of literature. Early diagnosis and surgical excision remains the mainstay of treatment.     

Distribution of primary afferent fibers within the sacrococcygeal dorsal horn: an autoradiographic study.

The spinal segmental distribution and intersegmental course of primary afferent fibers were studied by injecting (by pressure or iontophoresis) tritiated amino acids (L-proline or L-leucine) into spinal ganglia of coccygeal and sacral segments and autoradiographically analyzing histological sections of the spinal cord, particularly those regions lying dorsal to the central canal. The results from eight cats and three monkeys are described. A heavy projection of primary afferent fibers to the marginal zone (lamina I), the substantia gelatinosa Rolandi (lamina II), and throughout the nucleus proprius (laminae III-IV) was demonstrated. The projections to these three areas appeared to be substantially independent. Primary afferent fibers were found to course rostrally and caudally within the marginal zone, in the midline dorsal to the central canal, in Lissauer's tract, and in the dorsal columns. A crossed projection passed by way of the dorsal commissure to the contralateral marginal zone and to a region ventrolateral to the contralateral nucleus proprius. There was a distinct medial-to-lateral shift in the termination of primary afferent fibers in the substantia gelatinosa and in the dorsal portion of the nucleus proprius. The most medial distribution occurred immediately caudal to the entry zone of the primary afferent fibers, and the most lateral at the cephalad end of the segment immediately rostral to the entry level. Small (iontophoretic) injections revealed circumscribed fields of termination, approximately 40 micrometers by 70 micrometers (dorsoventrally) by 400 micrometers or more (rostrocaudally) in the substantia gelatinosa.     

Negative pressure wound therapy for a large skin ulcer following repair of huge myeloschisis with kyphosis in a newborn

Background

In surgery of repair for spina bifida, various skin plastic techniques are sometimes necessary due to large skin defect or subsequent ulcers in cases when approximation on the midline is difficult.

Case report

A baby was born with a large skin defect due to huge lumbar myeloschisis and kyphosis, which was repaired 2 days after birth using Limberg’s skin flap at the peak of kyphosis. Skin ischemia around the tip of the flap gradually enlarged and resulted in a large skin ulcer. We performed negative pressure wound therapy (NPWT) using a Vacuum Assisted Closure (V.A.C.®) therapy system for 4 weeks which shrank the ulcer remarkably. Subsequently, a pedicle skin flap without graft was performed to cover the rest of the ulcer, which adapted well without CSF leakage postoperatively.

Conclusion

A combination treatment of NPWT and skin plastic surgery was successfully performed for a very young infant with spina bifida. NPWT could be another useful option for the treatment of ulcer following spina bifida repair surgery, though surgeons should carefully confirm that there is no CSF leakage before and during the procedure.     

Effect of Brn-3a deficiency on parvalbumin-immunoreactive primary sensory neurons in the dorsal root ganglion

Immunohistochemistry for parvalbumin, a marker for primary proprioceptors, was performed on the dorsal root ganglion (DRG) of wildtype and knockout mice for Brn-3a at postnatal day 0 and embryonic day 18.5. The DRG contained many parvalbumin-immunoreactive (ir) neurons in wildtype (5.4%) and knockout mice (5.6%). Cell size analysis demonstrated that such neurons were mostly medium-sized to large in these mice. Therefore, it is unlikely that the survival of proprioceptors is dependent upon Brn-3a in the DRG. In the dorsal column and gray matter of the spinal cord of knockout mice, however, parvalbumin-ir nerve fibers were sparse compared to wildtype mice. The number of parvalbumin-ir varicosities around motoneurons decreased in the mutant. Thus, our data suggest that Brn-3a may play an important role in the central projection and terminal formation of DRG proprioceptors in the spinal cord.     

Nerve transplantation shows that motor end-plate disease is not a primary Schwann cell defect

Motor end-plate diseased (MED) mice have altered nerve impulse conduction velocities and refractory periods. To test whether these pathological properties are caused by a primary Schwann cell defect, nerves were transplanted from MED and wildtype (WT) animals onto WT recipients. The donor origin of cells in the regenerated nerve was assessed by prelabeling with [3H]thymidine and by electrophoretic analysis of glucose phosphate isomerase allotypes. Nerve fiber regeneration through MED and WT implants was equally efficient. No difference was found in nerve conductivities of MED and WT grafts. Therefore a primary defect in the Schwann cells of the MED mouse is unlikely.     

Regeneration of primary sensory axons into the adult rat spinal cord via a peripheral nerve graft bridging the lumbar dorsal roots to the dorsal column

This study investigated the feasibility of using a peripheral nerve autograft (NAG) to promote and guide regeneration of sensory axons from the caudal lumbar dorsal roots to the rostral dorsal column following a lower thoracic cordotomy in adult rats. After a left hemicordotomy at the T13 vertebra level and ipsilateral L3 and L4 rhizotomies, a peripheral NAG (peroneal nerve) was connected to the distal roots stumps, then implanted into the left dorsal column 10 mm rostral to hemicordotomy site (n = 12). After surgery, all animals of the experimental group experienced complete anesthesia in their left hindlimb. Three months later, a slight response to nociceptive stimulation reappeared in L3 and/or L4 dermatomes in 6 of the 12 experimental animals. None of these animals exhibited self-mutilation. Nine months after surgery, we performed retrograde tracing studies by injecting horseradish peroxidase (HRP) into the left dorsal column 30 mm rostral to the NAG implantation site. In eight animals, we found HRP-stained neurons in the left L3 and/or L4 dorsal root ganglia (DRG). The mean number of HRP-stained neurons per DRG was 71 +/- 92 (range 2-259). In control groups, no HRP-stained neurons were found in L3 or L4 DRG. Histological analysis of the NAG showed evidence of axonal regeneration in all 8 animals with positive retrograde labeling of DRG neurons. However, we did not find a statistical correlation between the number of HRP-stained neurons and the degree of sensory recovery. This study demonstrates that an NAG joining dorsal roots to the dorsal column, thus shunting the original CNS-PNS junction, can support regeneration of central axons from DRG primary sensory neurons into the dorsal column over distances of at least 30 mm despite the inhibitory influence of the CNS white matter.