A patient with posttraumatic lumbar radicular paresthesias is presented. The preoperative diagnosis of an epidural synovial cyst was considered. At surgery, an epidural synovial microcystic mass was found emanating from a distracted L4-5 facet joint and dissecting into the layers of the ligamentum flavum. A brief review of the condition is presented.

Electric Stimulation applied to the posterior surface of the spinal cord (SCS) is an established treatment in certain chronic pain syndromes resistant to con-ventional therapeutic procedures. Despite the clinical value of SCS, the mechanisms behind the efficacy of the method are largely unknown. Several neurotransmitters in the CNS (e.g. Opioids, serotonin, noradrenaline, substance P, GABA), have been pro-posed to be involved in the pain-alleviating effect of SCS. However, as yet there is no evidence that these would be involved in the beneficial effects of SCS. We have studied neurotransmitter release, using microdialysis techniques, in the spinal dorsal horn and the periaqueductal grey substance (PAG) of the rat and the cat, induced by SCS applied with current parameters equivalent to those used clinically in man. Up to now dialysates have been assayed for GABA, serotonin and substance P with highly sensitive methods. Three groups of studies have been carried out: (1) dorsal horn microdialysis in rats under halothane anesthesia during acute SCS; (2) dorsal horn microdialysis in cats under barbiturate anesthesia or following decerebration, and (3) PAG microdialysis in awake, unrestrained rats with chronic SCS. In the dorsal horn studies, microdialysis probes of different sizes were implanted in the lower lumbar dorsal horns. In the PAG studies, rats had guide cannulas for microdialysis stereotactically inserted into the PAG. SCS was applied at a low thoracic level with 50 or 100 Hz; 0.2 ms and an intensity amounting to ²/₃ of the motor threshold. The microdialysis probes were perfused with modified Ringer''s solution. Fractions of the dialysate were collected at various intervals. GABA and serotonin were assayed by reverse-phase HPLC, while substance P was investigated using a highly sensitive radioimmunoassay. SCS induced a significant release of GABA in the dorsal horn, most marked in the fraction following the stimulation period. In the rats with PAG microdialysis, the GABA level decreased significantly following two stimulation periods, although transitional increases during SCS were noted in some animals. In the decerebrated cat, a significant release of serotonin in the dorsal horn was obtained with SCS, while the levels of the metabolite 5-HIAA were little influenced by stimulation. On the contrary, in the decerebrated preparation there was no release of substance P in the dorsal horn with SCS, although in the intact cat under barbiturate anesthesia a significant release was induced. the observation paramters'' is consistent with the view that these substances may be involved in hibition of nociceptive transmission. Furthermore, there are hypersensitivity of wide dynamic symptom is often successfully treated by SCS. The putative role of substance P in SCS is more vague. There are descending pathways with a hypothetical inhibitory function whre substance P and serotonin coexist. The present observations might indicate that substance P is also involved in the beneficial effects of SCS ...

The ultrastructure of muscular innervation of the feline bladder base was studied eight and ten weeks following its decentralization by unilateral sacral ventral rhizotomy. In all samples, there was widespread regeneration of cholinergic axons that displayed initial transsynaptic degeneration a few weeks after the operation, with re-formation of cholinergic neuroeffector junctions. This was associated with reactive sprouting of adrenergic axons leading to adrenergic hyperinnervation, as well as the emergence of a population of cholinergic and adrenergic axons containing strikingly abundant polymorphous large densccore vesicles that resembled those naturally present in paraganglionic cells, paraneurons. and neurosecretory cells. This increased content of large dense-core vesicles imparts a probable "peptidergic" character to some regenerating and many reactively sprouting adrenergic axons. Our findings suggest that the long-term dysfunction of the parasympathetic-decentralized bladder base is determined by the interplay of reestablished cholinergic, exaggerated adrenergic, and emergent probable "peptidergic" axonal influence and neuroeffector transmission.Key words: neurogenic bladder, parasympathetic-decentralized bladder, sacral ventral rhizotomy, axonal regeneration, axonal sprouting, adrenergic hyperinnervation, "peptidergic" INTRODUCTIONSome previous studies indicate that the parasympathetic-decentralized vesical muscularis eventually regains some cholinergic function, becomes hyperinnervated by adrenergic axons, and develops some altered parasympathetic and sympathetic responses [Sundin and Dahlstrom, 1973;NorlCn, 1976;Sundin et al, 1977; Dahlstrom, 1978; Alm and ElmCr, 1979; Banns et al, 1980; Ekstrom and ElmCr, 1980; Ekstrom, 19811. In the previous part of this report [Elbadawi et al, 19841, it was shown that parasympathetic decentralization of the feline bladder by unilateral sacral ventral rhizotomy leads within 2-4 weeks to transsynaptic degeneration of cholinergic nerves of the bladder base, with preservation of its adrenergic nerves. Concomitantly, the intervaricose segments of many cholinergic and adrenergic axons had features of early regeneration or sprouting. In the present report, the long-term effects of the same procedure on the ultrastructure of intrinsic nerves of the bladder base are described, and their implications in regard to its neurogenic dysfunction are discussed. MATERIALS AND METHODSSix sexually mature male cats (10-12 months of age; 3-4.2 kg body weight) were subjected to left sacral ventral rhizotomy. Specimens of the bladder base were obtained for ultrastructural study eight and ten weeks after operation (three cats each period). All procedures of the operation, postoperative care, specimen collection, and sample processing are the same as those described in the previous report [Elbadawi et al, 19841. RESULTSThree neural changes were observed in all samples, namely, regained normal structure of cholinergic terminals and varicosities, considerable increase of adrenergic relati...

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