Dysethesia due to irritation of the dorsal root ganglion following lumbar transforaminal endoscopy: Analysis of frequency and contributing factors.

BACKGROUND: New onset of acute dysethetic leg pain due to irritation of the dorsal root ganglion (DRG) following uneventful recovery from an expertly executed lumbar transforaminal endoscopic decompression is a common problem. Its incidence and relation to any risk factors that could be mitigated preoperatively are not well understood. METHODS: We performed a multicenter frequency analysis of DRG irritation dysesthesia in 451 patients who underwent lumbar transforaminal endoscopic decompression for herniated disc and foraminal stenosis. The 451 patients consisted of 250 men and 201 women with an average age of 55.77 ± 15.6 years. The average follow-up of 47.16 months. The primary clinical outcome measures were the modified Macnab criteria. Chi-square testing was employed to analyze statistically significant associations between increased dysesthesia rates, preoperative diagnosis, the surgical level(s), and surgeon technique. RESULTS: At final follow-up, Excellent (183/451; 40.6 %) and Good (195/451; 43.2 %) Macnab outcomes were observed in the majority of patients (378/451; 83.8 %). The majority of study patients (354; 78.5 %) had an entirely uneventful postoperative recovery without any DRG irritation, but 21.5 % of patients were treated for it in the immediate postoperative recovery period with supportive care measures including activity modification, transforaminal epidural steroid injections, non-steroidal anti-inflammatories, gabapentin, or pregabalin. There was no statistically significant difference in dysesthesia rates between lumbar levels from L1 to S1, or between single (DRG rate 21.8 %) or two-level (DRG rate 20.2 %) endoscopic decompression (p = 0.742). A statistically significantly higher incidence of postoperative dysesthesia was observed in patients who underwent decompression for foraminal stenosis (38/103; 27 %), and recurrent herniated disc (7/10; 41.2 %; p = 0.039). There were also statistically significant variations in dysesthesia rates between the seven participating clinical study sites ranging from 11.6%-33% (p = 0.002). Unrelenting postoperative dysesthetic leg pain due to DRG irritation was statistically associated with less favorable long-term clinical outcomes with DRG rates as high as 45 % in patients with a Fair and 61.3 % in patients with Poor Macnab outcomes (p < 0.0001). CONCLUSIONS: Postoperative dysesthesia following transforaminal endoscopic decompression should be expected in one-fifth of patients. There was no predilection for any lumbar level. Foraminal stenosis and recurrent herniated disc surgery are risk factors for higher dysesthesia rates. There was a statistically significant variation of dysesthesia rates between participating centers suggesting that the surgeon skill level is of significance. Severe postoperative dysesthesia may be a predictor of Fair of Poor long-term Macnab outcomes.

Differential response of pineal microglia to surgical versus pharmacological stimuli.

Microglial cells are one of the interstitial elements of the pineal gland (PG). We recently reported the pattern of microglia colonization and activation, and microglia-Pax6+ cell interactions during normal pineal ontogeny. Here, we describe the dynamics of microglia-Pax6+ cell associations and interactions after surgical or pharmacological manipulation. In adult rats, the superior cervical ganglia (SCG) were exposed, and either bilaterally excised (SCGx) or decentralized (SCGd). In the SCGx PGs, the density of Iba1+ microglia increased after surgery and returned to sham baseline levels 13 days later. Pineal microglia also responded to SCGd, a more subtle denervation. The number of clustered Iba1+ /PCNA+ /ED1+ microglia was higher 4 days after both surgeries compared to the sham-operated group. However, the number of Pax6+ /PCNA- cells and the percentage of Pax6+ cells contacted by and/or phagocytosed by microglia increased significantly only after SCGx. Separate groups of rats were treated with either bacterial lipopolysaccharides (LPS) or doxycycline (DOX) to activate or inhibit pineal microglia, respectively. Peripheral LPS administration caused an increase in the number of clustered Iba1+ /PCNA+ /ED1+ microglial cells, and in the percentage of Pax6+ cells associated with and/or engulfed by microglia. In the LPS-treated PGs, we also noted an increase in the number of PCNA+ cells that were Iba1- within the microglial cell clusters. The density of Pax6+ cells did not change after LPS treatment. DOX administration did not influence the parameters analyzed. These data suggest that pineal microglia are highly receptive cells capable of rapidly responding in a differential manner to surgical and pharmacological stimuli.

Infraareolar access for thoracoscopic sympathectomy to treat primary hyperhidrosis.

We herein present a new technique for performing thoracoscopic sympathectomy to treat primary hyperhidrosis in both genders and all ages through the mammary infraareolar access associated with the axillary access. We believe that these points of access are feasible and safe, and result in an excellent cosmetic outcome without compromising the efficacy of the thoracoscopic sympathectomy. The existence of adhesions between the parietal and visceral pleura, the presence of large breasts, and lactation made it difficult to perform the surgery, but did not make it impossible to apply the technique using the infraareolar access. However, the presence of breast implants is a contraindication for the new access.

Dorsal root ganglionectomy for the diagnosis of sensory neuropathies. Surgical technique and results.

BACKGROUND: Inflammatory diseases stand out among sensory neuronopathies because, in their active phase, they can be treated with immunosuppressive agents. Immunosuppressive therapy may present severe adverse effects and requires previous inflammatory activity confirmation. Sensory neuronopathies are diagnosed based on clinical and EMG findings. Diagnostic confirmation and identification of inflammatory activity are based on sensory ganglion histopathological examination. We describe the surgical technique used for dorsal root ganglionectomy in patients with clinical/EMG diagnosis of sensory neuronopathies. METHODS: The sensory ganglion was obtained from 15 patients through a small T7-T8 hemilaminectomy and foraminotomy to expose the C7 root from its origin to the spinal nerve bifurcation. In 6 patients, the dural cuff supposed to contain the ganglion was resected en bloc; and in 9 patients, the ganglion was obtained through a longitudinal incision of the dural cuff and microsurgical dissection from the ventral and dorsal roots and radicular arteries. All ganglia were histopathologically examined. RESULTS: No ganglion was found in the dural cuff in 2 patients submitted to en bloc removal, and the ganglion was removed in all patients who underwent microsurgical dissection. All but 2 patients that had ganglion examination presented a neuronopathy of nerve cell loss, 3 with mononuclear inflammatory infiltrate. These patients underwent immunosuppressive therapy, and 2 of them presented clinical improvement. No surgical complications were observed. CONCLUSIONS: Microsurgical dorsal root ganglionectomy for diagnosing inflammatory sensory ganglionopathies was effective and safe. Although safe, en bloc resection of the proximal dural cuff was not effective for this purpose.

Bone marrow stromal cells induce changes in pain behavior after sciatic nerve constriction.

Peripheral nerve injury, i.e. a single ligature nerve constriction (SLNC), triggers neuropathic pain. Bone marrow stromal cells (MSCs) have been observed to migrate to the injured tissues and mediate functional recovery following brain, spinal cord and peripheral nerve lesions. We have recently shown MSC selective migration to the ipsilateral lumbar (L3-6) dorsal root ganglia (DRGs) after a sciatic nerve SLNC. In this study, we have analyzed the thermal and mechanical sensitivities of animals subjected to a SLNC of the sciatic nerve and an ipsilateral intraganglionic MSC injection, using the von Frey and Choi tests. Control animals were subjected to the nerve lesion either alone or followed by the administration of phosphate-buffered saline (PBS) or bone marrow non-adherent mononuclear cells (BNMCs). All the animals were tested both before surgery and after 1, 3, 7, 14, 21, 28 and 56 days. Animals subjected to the sciatic nerve constriction developed ipsilateral mechanical and thermal allodynia already 3 days after the lesion. The allodynic responses were maintained even after 56 days. MSC administration prevented the generation of mechanical allodynia and reduced the number of allodynic responses to cold stimuli. On the contrary, the injection of either PBS or BNMCs could not counteract allodynia. These results suggest that MSCs may modulate pain generation after sciatic nerve constriction. The underlying mechanisms by which MSCs exert their actions on pain behavior need to be clarified.

Selective restoration of sensation by peripheral nerve grafts directly implanted into the contralateral C7 dorsal root ganglion: an experimental study in rat brachial plexus.

OBJECTIVE: In brachial plexus injuries, when the dorsal root ganglion (DRG) is avulsed from the spinal cord there is no possibility of direct repair. Therefore, in the present report the median nerve was connected directly to the contralateral C7 DRG, to restore forepaw sensation. METHODS: The ulnar nerve was sectioned, and a 15-mm segment of nerve was removed. The median nerve was sectioned, transposed dorsally, and repaired using a sural nerve graft directly implanted into the C7 contralateral DRG. Rats were then assessed 6 and 12 months later by behavioral, histological, and plasma extravasion techniques. RESULTS: All animals recovered sensation in the forepaw. Retrogradely labeled sensory neurons were demonstrated in the C7 DRG, and the whole forepaw was labeled after plasma extravasion induction by median nerve antidromic stimulation. Several myelinated and positively neurofilament-stained fibers were demonstrated in the grafted median nerve. CONCLUSION: The surgical strategy proposed might be a useful alternative to selective sensory repair in the emerging field of brachial plexus reconstruction by direct spinal cord surgery.

Evoked-potential monitoring during dorsal root entry zone surgery. Patients with chronic pain.

Somatosensory evoked potentials (SEP) were monitored intraoperatively in 15 patients who underwent spinal cord radiofrequency thermal dorsal root entry zone (DREZ) lesion procedures to treat chronic deafferentation pain. We found a significant correlation between transient latency shifts (recovery to prelesion values in the postlesioning period) of the first positive peak of the SEP (P1) during lesion production and the patients' subsequent postoperative neurological status (p less than 0.01). Transient increases in P1 latency above 2 ms were associated with detectable but transient postoperative sensorimotor deficits that resolved weeks to months after surgery. In 1 patient, the intraoperative P1 latency failed to return to baseline values; this patient had irreversible postoperative sensorimotor dysfunction. In 9 patients, we confirmed the value of recording bilateral SEP, using the contralateral side of the spinal cord (with no lesions) as a control. This experience has resulted in an improved SEP monitoring strategy: we now reconsider the risk-benefit ratio of additional DREZ lesions if early lesion production results in increased P1 latency. Rapid normalization of the P1 latency indicates that any postoperative deficits likely will resolve. Failure of P1 latency to return to control levels during the surgical wound closure period (approximately 1 h) indicates the high probability of permanent neurological deficits.

Evoked-potential monitoring during dorsal root entry zone surgery. An experimental animal model.

Spinal cord evoked potentials (SCEP) in response to epispinal stimulation were measured in an experimental animal model designed to define further the value of electrophysiological monitoring during dorsal root entry zone (DREZ) surgery. Thirteen cats underwent microsurgical stereotactic thermal radiofrequency lesions of the DREZ. The postmortem histological examination of the location and extent of the lesions were compared with the intraoperative electrophysiological and postoperative neurological effects. Despite the use of the stereotactic microsurgical technique, the sizes and the configurations of the DREZ lesions varied greatly. Changes in ascending and descending SCEP correlated highly with the extent of the histologically defined injury to the dorsal and lateral columns. SCEP monitoring during experimental DREZ surgery provided a sensitive indication of lesion invasion into the dorsal or lateral columns. The high degree of correlation between changes in descending SCEP and extension of the surgical lesion into the lateral column indicates that the SCEP technique is more sensitive than somatosensory cortical evoked potentials in the intraoperative electrophysiological assessment of corticospinal tract function, and it may prove to be a useful surgical adjunct during DREZ surgery in humans.