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Objective: Although transient neurologic symptoms may occur after neuraxial anesthetics with lidocaine, permanent neurologic symptoms (PNS) are unusual after uncomplicated continuous epidural analgesia (CEA). This report demonstrates that PNS may follow CEA uncomplicated by paresthesias, dural puncture, spinal hemorrhage, or intravascular local anesthetic injection; and performed with bupivacaine alone administered at high dosages with vasoconstrictors over a prolonged time period. Case Report: An obstetrical patient developed fixed left L5-S1 sensorimotor radiculopathy following L5-S1 level CEA with bupivacaine alone administered at high doses (270 mg) with a vasoconstrictor (epinephrine, 225 mg) over a prolonged time period (62 hours). Conclusions: CEA should be administered at higher lumbar levels for labor analgesia rather than at lumbosacral levels that may require higher volumes and concentrations of local anesthetics with greater potential for local anesthetic neurotoxicity. Local anesthetics with vasoconstrictors should only be used as sentinel markers of unrecognized intravascular entry, rather than as primary local anesthetics during CEA to avoid any potential for ischemic neuropathy.

Anti-epilepsy medications have frequently beenused in the treatment of neuropathic pain to reduce thetransmission of nociceptive signals. 1,2 Zonisamide is a sulfona-mide drug that was approved in 2000 for the adjunctive treat- ment of partial seizures in adults. Because of the unique com-bination of mechanisms through which zonisamide functions,it has potential to be a useful option in the treatment of re-fractory neuropathic pain. We present the case of a patientwith refractory neuropathic pain related to idiopathic poly-neuropathy, who responded to adjunctive treatment withzonisamide. Key Words: anticonvulsants, sulfonamides, adjunctivetherapy CASE REPORT A 53-year-old female presented for evaluation of chronicpain associated with idiopathic sensorimotor neurop-athy. Her symptoms began in 1992 with constant burn-ing in her toes that gradually intensified and extendedproximally to her knees. The pain was lancinating inquality, was exacerbated by light touch and heat, andwas associated with numbness in a stocking distribu-tion. Her pain intensity was rated an average of 9 out of10 on a visual analog scale (VAS), where 0 is no pain,and 10 is the worst pain imaginable. Her past medicalhistory was positive only for hypertension. Prior to pre-sentation, she had undergone extensive diagnostic test-ing for peripheral neuropathy, which included screeningfor diabetes, HIV, ethanol, Lyme disease, connective tis-sue disorders, occult malignancy, and heavy metals, allof which were negative. She was found to have a mildlylow vitamin B

Connections between the primary motor cortex (MI) and the corpus striatum were studied in the owl monkey. Representations of specific body movements were elicited in MI by microstimulation techniques, and the efferent projections from these stimulation sites were labeled with wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP). Dense projections were found in the putamen ipsilateral to the injection site and sparser projections occupied comparable areas in the contralateral putamen. Representations of hindpaw regions projected to the dorsomedial portion of the putamen with only slight extensions across cell bridges into the caudate nucleus. Representations of the forepaw and head projected to progressively more ventrolateral zones of the dorsal two-thirds of the putamen. Projections from injections of cortex representing discrete body movements terminated in an irregular or patchy distribution over a relatively large portion of the putamen. Extensive projections from relatively discrete injections in MI are indicative of a large degree of divergence and provide evidence for possible overlap from representations of relatively disparate body parts. The results are consistent with observations reported in other species of primates, but different from those seen in carnivores. This difference is discussed with regard to possible general features of corticostriate organization. Many regions of the cerebral cortex provide afferent connections to the corpus striatum and have been shown to terminate in a topographic fashion (Kemp and Powell, '70; Yeterian and VanHoesen, '78; Selemon and GoldmanRakic, '85). In primates, the frontal, parietal, and temporal association cortices project predominantly to the caudate nucleus (Goldman and Nauta, '77; Kunzle, '78; Yeterian and VanHoesen, '78; VanHoesen et al., '81; Selemon and Goldman-Rakic, '85; Alexander et al., '86; Arikuni and Kubota, '86; Jayaraman, '87) whereas motor, premotor, supplementary motor, and somatosensory cortices project predominantnly to the putamen (Kunzle, '75, '77, '78; Jones et al., '77; Jurgens, '84; Liles and Updyke, '85; Alexander et al., '86). In general, corticostriate projections that originate in primary motor cortex are broadly distributed in the putamen and are organized in a basically topographic fashion; projections from those portions of motor cortex related to the representation of the head terminate primarily in the ventral putamen whereas the representations of the upper limb, trunk, lower limb, and tail project to successively more dorsal portions of the putamen (Kiinzle, '75, '77; Jones et al., '77). The general topographic organization of projections from primary motor cortex to the corpus striatum provides the basis for much of our understanding of functional localization in the neostriatum. This framework, however, was determined in early studies in which the sites for injection were anatomically defined according to the physiological map of Woolsey ('58). Conclusions are based on the assumption that large injections in precentral cortex involve specific body representations identical to those depicted in the same relative position of precentral cortex in previously generated summary stimulation maps (Woolsey, '58). While providing a general framework, however, it is difficult to assign a specific role to corticostriate projections in particular isolated movements when large injections, possibly involving several body representations, are utilized. Summary maps of the primate primary motor cortex have been generated in several laboratories by using contemporary

Interhemispheric connections of visual cortex were studied in owl monkeys, marmosets, and galagos after multiple injections of horseradish peroxidase into one cerebral hemisphere. Areal patterns of connections were revealed in sections of cortex that was flattened and cut parallel to the surface. Results were related to the locations of known visual areas, especially in owl monkeys, in which more visual areas have been established. The connection patterns in owl monkeys and marmosets are very similar, suggesting that the organization of visual cortex differs little in these two New World simians. Galagos have a basically similar pattern, but the connections are more widespread. In all three primates, connections are not restricted to cortex representing the line of decussation of the retina, and even striate cortex has connections displaced from the border. These connections extend up to 2 mm into area 17 in owl monkeys, and they are most extensive in galagos, where they form foci that are coextensive with regions of high cytochrome oxidase activity. Connections are concentrated in the caudal half of area 18, but protrusions of connections cross of the width of the field. The middle temporal visual area (MT) has unevenly distributed connections throughout, with some increase in density along the border. The dorsomedial visual area (DM) of owl monkeys has connections restricted to the rostral border, and a similar region of sparse connections identifies the probable location of DM in marmosets and galagos. Caudal parts of the dorsolateral visual area (DL) of owl monkeys have dense interhemispheric connections. Other visual areas are characterized by unevenly distributed clumps of connections, suggesting that functions are not uniformly distributed, and that semiregular processing modules exist. The results indicate that most extrastriate visual neurons are subject to interhemispheric influences and support the conclusion that callosal connections are functionally heterogeneous.

The callosal connections within the posterior parietal and occipital cortices were studied in the squirrel monkey with horseradish peroxidase tracing techniques. The data were evaluated with particular emphasis on the relationship of major callosal connections along the 17-18 border. The overall pattern of callosal connections in the squirrel monkey also was compared with callosal patterns in other New World simians. Our results show that the dense band of callosal connections along the 17-18 border in the squirrel monkey differs from the connections observed in other New World monkeys in that it is virtually confined to area 18 and avoids area 17. In addition to a continuous band of callosal connections in area 18 that parallels the 17-18 border, rostral extensions of the band are oriented perpendicular to the 17-18 border and present an obvious periodicity. The remaining parieto-occipital cortex contains a complex pattern of callosal connections that is strikingly similar to patterns reported for other New World monkeys. Thus, it is likely that the dorsolateral extrastriate visual cortex in the squirrel monkey is organized in a manner similar to that found within other New World monkeys.

The connections of the cortical dysgranular "unresponsive zone" (UZ) (Sur et al.: J. Comp. Neurol. 179:425-450, '78) in the grey squirrel were studied with horseradish peroxidase and autoradiographic techniques. The results of these experiments show that the major subcortical connections of the unresponsive zone are in large part reciprocal. Connections are distributed within the thalamus in a poorly defined region including restricted portions of several nuclei that lie along the rostral, dorsal, and caudal borders of the ventral posterior nucleus. Additional thalamic connections of the UZ terminate in the reticular nucleus and are reciprocally related to the paralaminar and central median nuclei. Extrathalamic terminations were observed in the zona incerta, the intermediate and deep layers of the superior colliculus, the red nucleus, and several subdivisions of the pontine nuclei. The similarity between the pattern of subcortical connections of the UZ in the grey squirrel and patterns reported for the parietal septal region in rats (Chapin and Lin: J. Comp. Neurol. 229:199-213, '84) and for area 3a in primates (Friedman and Jones: J. Neurophysiol. 45:59-85, '81), suggests that the UZ in the grey squirrel may represent a counterpart of at least part of area 3a as described in primates. The results are further discussed with respect to a possible role of the thalamus in control or modulation of interhemispheric circuits and of the UZ in the modulation of nociceptive and kinesthetic pathways through the thalamus. Finally, the term parietal dysgranular cortex (PDC) is proposed as an alternative to denote the region currently called the unresponsive zone.

The contribution of each cortical lamina to intracortical circuitry was studied in the visual neocortex of the Pakistani hedgehog. Punctate laminar lesions were made electrolytically within the visual cortex, and after five to seven days the brains were processed and stained with the Fink-Heimer technique. The results of this study suggest that both horizontal and vertical connections are important to the organization of visual cortex in the hedgehog. The horizontal projections originate at three distinct cortical depths. Lesions in layer II reveal projections that traverse the inner one-half of layer I; lesions in layers III and IV reveal projections that traverse layer IV and that enter the cortical white matter; lesions in layers V and VI reveal projections that traverse the outer one-half of layer VI and that enter the cortical white matter. The vertical projections are oriented perpendicular to the pial surface. Layers II and III project to underlying layer V. Layers V and VI in turn contribute to a reciprocal projection back to all superficial cortical laminae. This anatomical data about intracortical circuitry is discussed with reference to the functional organization of visual cortex.

The topographic distribution of somesthetic interhemispheric projections was studied in grey squirrels using the Fink-Heimer technique follow- ing large aspiration lesions of' the corpus callosum. On the day of perfusion, receptive fields were determined for microelectrode recording sites in the first, S I, and second, S 11, somatosensory areas of cortex, and small electrolytic lesions were made in order to identify some of these sites in prepared brain sections. The cortex was then separated from the rest of the brain, flattened, and cut parallel, so that with the aid of the reference lesions, the total pattern of degeneration could be related to a surface view of the brain and to previous electrophysiological maps of S I (Sur et al., '78) and S I1 (Nelson et al., '79). The results show that callosal terminations are unevenly distributed in S I and S 11, and suggest that there are several categories of callosal inputs to S I. A major region of terminations is in the architectonically distinct "unresponsive zone" within SI, and perhaps in other similar, but narrower, specialized zones within and bordering S I, as previously described in rats (Ryugo and Killackey, '75; Wise and Jones, '76, '78 Akers and Killackey, '78). Other callosal projections terminate within the responsive regions of S I. These regions include at least some of the representation of the body midline, most clearly the midline of the representations of the upper and lower face, as well as regions unrelated to the midline of the body. Most or all of the SI cortex responsive to stimuli away from the midline on the upper and lower lips, the mystacial vibrissae, and the glabrous forepaw was almost free of direct callosal terminations. Except for a central core region, most of S I1 appears to receive a moderate distribution of callosal inputs. Patterns of callosal connections in parietal cortex have been studied in a range of mamma- lian species with the consistent observation that terminations are unevenly distributed within the first (S I) and second (S 11) somato- sensory representations (for review see Akers and Killackey, '78). Many of these studies have attempted to relate the observed distribution of terminations to prevailing concepts of how the body is represented in these two fields, with the result that several different, although not nec- essarily incompatible, concepts of the func- tional roles of callosal connections have evolved. Two different explanations were used to account for the conclusion that the represen- tations of the distal limbs have few or no callosal connections in S I and S 11. The earlier view was that the separate maps of the contra- lateral body surface in each hemisphere are connected along the representations of the dor- sal midline of the body through the corpus callosum so as to form continuous or joined rep- resentations (Ebner and Myers, '62, '65; Ebner, '69; Jones, '67; Jones and Powell, '68, '69a, '73; Pandya and Vignolo, '69; Karol and Pandya, '71; Jones et al., '75; Shanks et al., '75) in a manner analogous to the joining of the visual hemifield representations along the vertical meridian. An alternative explanation for this conclusion is that commissural terminations are devoted to those parts of the two hemirepre- sentations that have integrated or coordinated sensory-motor functions, while callosal connec- tions are lacking in parts of S I and S I1 with highly independent or "lateralized functional roles (Jacobson, '70; Yorke and Caviness, '75).

Corpus callosum connections of parietal and motor cortex were studied in New World owl monkeys (Aotus trivirgatus) and Old World macaque monkeys (Macaca fascicularis) after multiple injections of 3H-proline and horseradish peroxidase, HRP, into one cerebral hemisphere, and extensive microelectrode mapping of architectonic Areas 3b, 1, and 2 of the other hemisphere. Results were obtained both from parasagittal brain sections cut orthogonal to the brain surface and from sections from flattened brains cut parallel to the brain surface. Cortical fields varied in density of callosal connections, and the density of connections varied according to body part within sensory representations. Thus, Area 3b had few, Area 1 had more, and Area 2 had relatively dense callosal connections. Within each of these fields, connections were much less dense for the representations of the glabrous hand and foot and much more dense for the representations of the face and trunk. For the representation of the hand, retrogradely labeled cells were extremely sparse in Area 3b, moderately sparse in Area 1, and moderate in Area 2. There were less dense callosal connections in the hand representations of Areas 3b, 1, and 2 in macaque as compared to owl monkeys. Label in posterior parietal cortex was uneven with zones of extremely dense connections. A large region of very dense callosal connections was noted in motor cortex just medial to the probable location of the hand representation. In all regions, callosally projecting cells appeared to be more broadly distributed than callosal terminations. In no region was the discontinuous arrangement of callosal connections obviously organized into an extensive pattern of mediolateral or rostrocaudal bands or strips.