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John J. Moossy, Blaine S. Nashold Jr., Dennis Osborne and Allan H. Friedman

✓ The association of avulsive lesions and pain has been well established in avulsions of the brachial plexus from the cervical spinal cord, but avulsive lesions of the conus medullaris have not previously been recognized or documented by direct observation. Six patients with intractable lower-extremity pain due to avulsion of nerve roots from the conus medullaris were treated by thoracolumbar laminectomy and dorsal root entry zone (DREZ) lesions. Patients with avulsion of lumbosacral roots from the conus medullaris have a characteristic clinical presentation. They are usually young men who, as a result of a motorcycle accident, have suffered multiple pelvic or long-bone fractures or traumatic amputation of part of the lower extremity. Early in their course there is pain not directly attributable to the injured part. The pain is described as intense and burning, with episodic radiation and electric shock-like sensations in the injured or phantom limb. If the leg is intact, there is usually a dermatomal pattern to the distribution of the pain and neurological deficit. A myelogram often reveals a traumatic pseudomeningocele similar to those seen in the cervical region after avulsion of the brachial plexus. Surgical exploration of the conus medullaris usually reveals the extent of nerve root avulsion, and an appropriate DREZ operation can be performed.

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Peter C. Gerszten, John J. Moossy, John C. Flickinger and William C. Welch

Object. The authors of clinical studies have demonstrated a significant association between the presence of extensive post—lumbar discectomy peridural scar formation and the recurrence of low-back and radicular pain. Low-dose perioperative radiotherapy has been demonstrated to inhibit peridural fibrosis after laminectomy in animal models. The present study was designed to evaluate the clinical efficacy of preoperative irradiation in patients with failed—back surgery syndrome due to peridural fibrosis who underwent reexploration and nerve root decompression.

Methods. Ten patients with symptomatic post—discectomy peridural fibrosis were randomized. Half of the patients underwent 700-cGy external-beam irradiation to the operative site 24 hours prior to reexploration and decompressive treatment of their symptomatic nerve root(s) (treatment group) and the other half underwent reexploration and decompressive treatment without preoperative irradiation (control group). All patients underwent simulated irradiation so neither patient nor surgeon was aware of the patient's group. In all patients the antiadhesion product ADCON-L was placed over the affected nerve root at the time of surgery. Clinical outcome was assessed using the American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Section Lumbar Disc Herniation Study Questionnaire at baseline, 6 weeks, 3 months, and 1 year follow up.

Five men and five women (mean age 42 years) underwent randomization and surgery. Three patients underwent reexploration at L4–5, four at L5—S1, and three at both levels. No complication was associated with irradiation, and no new neurological deficits occurred. At 1-year follow-up examination, three irradiation-treated patients were pain free and two experienced improvement. In the control group, three patients experienced improved pain relief and two were unchanged. There was a trend toward better outcome at 1 year in the radiotherapy-treated group (p = 0.056).

Conclusions. Preoperative low-dose external-beam irradiation improved clinical outcomes after reexploration and decompression of nerve roots affected by postlaminectomy peridural fibrosis causing radicular pain. The addition of preoperative irradiation may improve outcome in patients who undergo reoperation for recurrent radicular pain associated with a significant amount of peridural fibrosis, particularly now that no antiadhesion product is available for clinical use.

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Joseph T. King Jr., John J. Moossy, Joel Tsevat and Mark S. Roberts

Object. Investigators reporting decompressive surgery to treat patients with cervical spondylotic myelopathy (CSM) have described inconsistent benefits. In the present study the authors used three types of outcomes instruments to assess the results of CSM surgery.

Methods. The authors collected prospective baseline and 6-month follow-up data in a cohort of 62 patients with CSM. Data collection included those pertaining to demographics; symptoms; physical findings; myelopathy severity; health status measured with the Short Form—36; and health values according to the standard gamble, time trade-off, visual analog scale, and willingness to pay. Rank-order methods were used to compare surgical and nonsurgical patients, and multivariate regression techniques adjusting for baseline characteristics were performed to examine the effects of surgery.

During the study period, 28 patients underwent surgery, 34 did not, and there were no baseline differences between the two groups in demographics, symptoms, myelopathy scores, health status, or health values (p ≥ 0.120 in all domains); there was a greater prevalence of hand intrinsic muscle atrophy (p = 0.035) and Hoffmann sign (p = 0.006) in the surgery-treated group. Neither raw comparisons nor regression analyses showed a consistent surgery-related benefit. There were sporadic associations between worse outcomes and older patients, higher income, Babinski sign, longer duration of CSM symptoms, hand clumsiness, lower-extremity numbness, and multilevel surgery (p ≤ 0.049 for all).

Conclusions. Analysis of results obtained in the 62 patients with CSM failed to show a surgery-related benefit despite the use of three classes of outcomes instruments. Patient demographics, symptoms, physical signs, and the surgical approach may explain some of the variation in outcomes in patients with CSM.

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Paul Gardner, Amin Kassam, Carl Snyderman, Arlan Mintz, Ricardo Carrau and John J. Moossy

✓ Cerebrospinal fluid (CSF) leakage following endoscopic endonasal skull base resection can be a significant problem. A method for securing tissue grafts is needed. In this paper the authors used an endonasal suturing device to secure the graft reconstruction following endonasal tumor resection.

The U-Clip anastomotic device (Medtronic), developed for cardiovascular anastomoses, was used to secure the tissue graft to native dura. A specialized needle driver and hemoclip applier were used for the application and deployment of this device. No suture tying was necessary, facilitating its endonasal application.

The graft was successfully secured in its desired position to native dura by using the U-Clip anastomotic device. The patient did not suffer a postoperative CSF leak, and postoperative imaging and endoscopy revealed that the graft was in a good position. There was no complication from the use of the device.

The U-Clip anastomotic device can be used as a suture device during endonasal surgery. It may prevent tissue graft migration and help prevent CSF leakage.

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Paul A. Gardner, Pawel G. Ochalski and John J. Moossy

Palmar hyperhidrosis is a disorder of the autonomic nervous system characterized by excessive perspiration of the palms, but may involve other body parts as well. Traditional posterior approaches have been performed less often in favor of less invasive thoracoscopic sympathectomies, which have a high success rate with low associated morbidity. However, some patients are not candidates for a transthoracic surgery and may need an alternative treatment strategy.

In situations in which a posterior approach may be necessary, the authors have developed a minimal access endoscopic-assisted dorsal sympathectomy procedure, applying minimally invasive spine muscle splitting techniques. The authors believe that the development of this technique may help to minimize surgical morbidity associated with the traditional posterior approach by reducing pain, tissue damage, and length of postoperative recovery. This paper is a report on the successful treatment of palmar hyperhidrosis using a minimally invasive posterior technique and describes the surgical approach and outcomes in 2 patients who have been treated in this manner.

Two patients underwent minimally invasive endoscopic-assisted posterior thoracic sympathectomy for hyperhidrosis. Both patients experienced relief of their symptoms after surgery with follow-up durations of 32 and 9 months and length of stays of 0.9 and 2.8 days, respectively. One patient suffered a unilateral Horner syndrome and underwent an eyelid lift. The other patient was readmitted to the hospital 2 days after discharge with atelectasis. She was obese and suffered from chronic obstructive pulmonary disease at baseline, which were reasons she opted for a posterior approach. Neither patient suffered a pneumo- or hemothorax.

Minimally invasive endoscopic-assisted posterior thoracic sympathectomy can be safely performed for relief of hyperhidrosis. The procedure has risks for the usual complications of sympathectomy. This technique may provide an alternative to thoracoscopic approaches, especially in those patients with pulmonary disease or obesity.

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Paul A. Gardner, Johnathan Engh, Dave Atteberry and John J. Moossy


External ventricular drain (EVD) placement is one of the most common neurosurgical procedures performed. Rates and significance of hemorrhage associated with this procedure have not been well quantified.


All adults who underwent EVD placement at the University of Pittsburgh Medical Center between July 2002 and June 2003 were evaluated for catheter-associated hemorrhage. Patients without postprocedural imaging were excluded.


Seventy-seven (41%) of 188 EVDs were associated with imaging evidence of hemorrhage after either placement or removal. Most of these were insignificant, punctate intraparenchymal, or trace subarachnoid hemorrhages (51.9%). Thirty-seven (19.7%) were associated with larger hemorrhages, which were divided into 3 groups according to volume of hemorrhage: 16 patients (8.5%) had < 15 ml of hemorrhage, 20 (10.6%) had hemorrhages of > 15 ml or associated intraventricular hemorrhage, and in 1 case there was a subdural hematoma that required surgical evacuation. No hemorrhages larger than punctate or trace were seen after EVD removal. Hemorrhage was associated with 44.3% of EVDs placed in an intensive care unit compared with 34.8% in EVDs placed in the operating room (p > 0.10).


External ventricular drain placement has a significant risk of associated hemorrhage. However, the hemorrhages are rarely large and almost never require surgical intervention. There is a favorable trend, but no significant risk reduction when EVDs are placed in the operating room rather than the intensive care unit.

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Oral Presentations

2010 AANS Annual Meeting Philadelphia, Pennsylvania May 1–5, 2010

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Nestor D. Tomycz and John J. Moossy

Brachial plexus avulsion and limb amputation are often associated with intractable chronic pain. Dorsal root entry zone (DREZ) thermocoagulation is an effective surgical treatment for upper-extremity deafferentation pain. The authors describe the clinical follow-up and imaging in a patient who underwent DREZ thermocoagulation 26 years ago for postamputation phantom limb syndrome with associated brachial plexus avulsion. This patient continues to have successful pain control without phantom limb sensation and has never experienced a recurrence of his left upper-extremity pain syndrome. This report lends credibility to the notion that, among ablative neurosurgical pain operations, DREZ thermocoagulation may provide the greatest durability of pain control.

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Jeffrey R. Balzer, Nestor D. Tomycz, Donald J. Crammond, Miguel Habeych, Parthasarathy D. Thirumala, Louisa Urgo and John J. Moossy


Spinal cord stimulation (SCS) is being currently used to treat medically refractory pain syndromes involving the face, trunk, and extremities. Unlike thoracic SCS surgery, during which patients can be awakened from conscious sedation to confirm good lead placement, safe placement of paddle leads in the cervical spine has required general anesthesia. Using intraoperative neurophysiological monitoring, which is routinely performed during these cases at the authors' institution, the authors developed an electrophysiological technique to intraoperatively lateralize lead placement in the cervical epidural space.


Data from 44 patients undergoing median and tibial nerve somatosensory evoked potential (SSEP) monitoring during cervical laminectomy or hemilaminectomy for placement or replacement of dorsal column stimulators were retrospectively reviewed. Paddle leads were positioned laterally or just off midline and parallel to the axis of the cervical spinal cord to effectively treat what was most commonly a predominant unilateral pain syndrome. During SSEP recording, the spinal cord stimulator was activated at 1.0 V and increased in increments of 1.0 V to a maximum of 6.0 V. A unilateral reduction or abolishment of SSEP amplitude was regarded as an indicator of lateralized placement of the stimulator. A bilateral diminutive effect on SSEPs was interpreted as a midline or near midline lead placement.


Epidural stimulation abolished or significantly reduced SSEP amplitudes in all patients undergoing placement for a unilateral pain syndrome. In 15 patients, electrodes were repositioned intraoperatively to achieve the most robust SSEP amplitude reduction or abolishment using the lowest epidural stimulation intensity. In all cases in which a significant unilateral reduction in SSEP was observed, the patient reported postoperative sensory alterations in target locations predicted by intraoperative SSEP changes. Placement of cervical spinal cord stimulators for bilateral pain syndromes often resulted in bilateral but asymmetrical SSEP changes. In no cases were significant SSEP changes, other than those induced using the device to directly stimulate the dorsal surface of the spinal cord, observed. No case of new postoperative neurological deficit was observed.


Somatosensory evoked potentials can be used safely and successfully for predicting the lateralization of cervical spinal cord stimulator placement. Moreover, they can also intraoperatively alert the surgical team to inadvertent displacement of a lead during anchoring. Further studies are needed to determine whether apart from assisting with proper lateralization, SSEP collision testing may help to optimize electrode positioning and improve pain control outcomes.