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Resection of benign sciatic notch dumbbell-shaped tumors

Robert J. Spinner, Toshiki Endo, Kimberly K. Amrami, Eric J. Dozois, Dusica Babovic-Vuksanovic, and Franklin H. Sim


The operative management of combined intrapelvic and extrapelvic sciatic notch dumbbell-shaped tumors is challenging. The relatively rare occurrence of these tumors and the varied extent of disease have made it difficult for surgeons to establish definitive surgical indications or predict favorable neurological outcomes based on preoperative imaging data.


In the past 3 years, the authors treated five patients presenting with radiating leg pain as a result of benign sciatic notch dumbbell-shaped tumors. These tumors in three patients with unilateral leg symptoms were considered unresectable by other neurosurgeons because of presumed direct intrinsic neural involvement. After high-resolution magnetic resonance (MR) imaging demonstrated that the extensive tumors were separate from the sciatic nerve and the lumbosacral plexus, however, these patients underwent a combined one-stage transabdominal and posterior transgluteal complete resection. Normal neurological status was maintained postoperatively in these three patients, and after more than 1 year of postoperative follow up, there were no tumor recurrences.

In two patients with bilateral symptoms and extensive tumor burden, serial MR images showed that innumerable tumors directly involved the entire cross-sectional area of the sciatic nerves and extended longitudinally to the lumbosacral plexuses. Tumor debulking or resection in these patients would have resulted in neurological deficits and would not have addressed their neuropathic pain, and therefore no surgery was performed. These two patients were treated pharmacologically and advised to monitor their tumor status over the course of their lifetimes in case of malignant transformation of the tumor.


A combined one-stage transabdominal and transgluteal approach allows safe resection of selected benign but extensive sciatic notch tumors. High-resolution MR imaging is a useful tool in the management of these tumors because it allows the surgeon to visualize the anatomical relationships of the tumor to the sciatic nerve. The authors believe that as this imaging technology advances, it will provide surgeons with a method to predict definitively which sciatic notch tumors displace rather than directly involve the sciatic nerve, and therefore indicate which tumors can be resected safely and completely.

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Intraneural Ganglion Cyst

Robert J. Spinner, Stephen W. Carmichael, and John L. D. Atkinson

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Suprascapular intraneural ganglia and glenohumeral joint connections

Robert J. Spinner, Kimberly K. Amrami, Michel Kliot, Shawn P. Johnston, and Joaquim Casañas


Unlike the more commonly noted paralabral cysts (extraneural ganglia), which are well known to result in suprascapular nerve compression, only four cases of suprascapular intraneural ganglia have been reported. Because of their rarity, the pathogenesis of suprascapular intraneural ganglia has been poorly understood and a pathoanatomical explanation has not been provided. In view of the growing literature demonstrating strong associations between paralabral cysts and labral (capsular) pathology, joint connections, and joint communications, the authors retrospectively reviewed the magnetic resonance (MR) imaging studies and postoperative results in the two featured patients to test a hypothesis that suprascapular intraneural ganglia would have analogous findings.


Two patients who presented with suprascapular neuropathy were found to have intraneural ganglia. Connections to the glenohumeral joint could be established in both patients through posterior labrocapsular complex tears. In neither patient was the joint connection identified preoperatively or intraoperatively, and cyst decompression was performed by itself without attention to the labral tear. The suprascapular intraneural ganglia extended from the glenohumeral joint as far proximally as the level of the nerves’ origin from the upper trunk in the supraclavicular fossa. Although both patients experienced symptomatic improvement after surgery, neurological recovery was incomplete. In both cases, postoperative MR images revealed cyst persistence. In addition, previously unrecognized superior labral anteroposterior (SLAP) Type II lesions (tears of the superior labrum extending anteroposterior and involving the biceps anchor at the labrum without actual extension into the tendon) were visualized. In one patient with a persistent cyst, an MR arthrogram was obtained and demonstrated a communication between the joint and the cyst.


The findings in these two patients support the synovial theory for intraneural ganglia. Based on their experience with intraneural ganglia at other sites, the authors believe that suprascapular intraneural ganglia arise from the glenohumeral joint, egress through a superior (posterior) labral tear, and dissect within the epineurium along an articular branch into the main nerve, following the path of least resistance. Furthermore, these two cases of intraneural ganglia with SLAP lesions are directly analogous to the many cases of paralabral cysts associated with these types of labral tears. By better understanding the origin of this unusual type of ganglia and drawing analogies to the more common extraneural cysts, surgical strategies can be formulated to address the underlying pathoanatomy, improve operative outcomes, and prevent recurrences.

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Contiguous conventional and plexiform schwannomas

J. Bradley White, Bernd W. Scheithauer, Kimberly K. Amrami, Dusica Babovic-Vuksanovic, and Robert J. Spinner

✓The authors present clinical, imaging, and histological features of two adult patients found to harbor a conventional schwannoma contiguous with a deep plexiform schwannoma. One patient had neurofibromatosis (NF) Type 2 (NF2), and both intracranial (bilateral oculomotor, trigeminal, acoustic, and hypoglossal schwannomas as well as meningiomas) and intraspinal (schwannomas and meningiomas) lesions. The proximal forearm lesions consisted of a conventional schwannoma and an underlying plexiform component. The second patient, who did not have NF2, presented with a similar enlarging mass in the distal arm; two contiguous lesions were resected. Both patients exhibited distinct, readily identifiable, magnetic resonance imaging features. Plexiform schwannomas are rare lesions that occur sporadically or, on occasion, in association with NF2 or meningiomas with or without multiple schwannomas. The authors believe that a more careful examination of patients with NF2 may show that these people have a higher incidence of plexiform schwannoma than previously thought. Pathological confirmation is crucial in distinguishing plexiform schwannomas from plexiform neurofibromas, because the latter are directly associated with NF1 and have a significant tendency to undergo malignant transformation. To the best of the authors’ knowledge, this is the first report of a conventional schwannoma contiguous with a deep plexiform schwannoma.

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Brachial plexus surgery, the “orphan drug,” whose time has come

Robert J. Spinner, Alexander Y. Shin, and Allen T. Bishop

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Delayed central nervous system superficial siderosis following brachial plexus avulsion injury

Report of three cases

Aaron A. Cohen-Gadol, William E. Krauss, and Robert J. Spinner

Chronic subarachnoid hemorrhage may cause deposition of hemosiderin on the leptomeninges and subpial layers of the neuraxis, leading to superficial siderosis (SS). The symptoms and signs of SS are progressive and fatal. Exploration of potential sites responsible for intrathecal bleeding and subsequent hemosiderin deposition may prevent disease progression. A source of hemorrhage including dural pathological entities, tumors, and vascular lesions has been previously identified in as many as 50% of patients with SS. In this report, the authors present three patients in whom central nervous system SS developed decades after brachial plexus avulsion injury. They believe that the traumatic dural diverticula in these cases may be a potential source of bleeding. A better understanding of the pathophysiology of SS is important to develop more suitable therapies.

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Gracilis free muscle transfer for restoration of function after complete brachial plexus avulsion

Kimberly A. Barrie, Scott P. Steinmann, Alexander Y. Shin, Robert J. Spinner, and Allen T. Bishop


The authors report the functional outcomes after functioning free muscle transfer (FFMT) for restoration of the upper-extremity movement after brachial plexus injury (BPI).


The authors conducted a retrospective review of 36 gracilis FFMT procedures performed in 27 patients with BPI between 1990 and 2000. Eighteen patients underwent a single gracilis FFMT procedure for restoration of either elbow flexion (17 cases) or finger flexion (one case). Nine patients underwent a double free muscle transfer for simultaneous restoration of elbow flexion and wrist extension (first muscle) and finger flexion (second muscle), combined with direct triceps neurotization. The results obtained in 29 cases of FFMT in which the follow-up period was 1 year are reported.

Neurotization of the donor muscle was performed using the musculocutaneous nerve (one case), spinal accessory nerve (12 cases), or multiple intercostal motor nerves (16 cases). Two second-stage muscle flaps failed secondary to vascular insufficiency. Mean electromyography-measured reinnervation time was 5 months. At a minimum follow-up period of 1 year, five muscles achieved less than or equal to Grade M2, eight Grade M3, four Grade M4, and 12 Grade M5. Transfer for combined elbow flexion and wrist extension compared with elbow flexion alone lowered the overall results for elbow flexion strength. Seventy-nine percent of the FFMTs for elbow flexion alone (single transfer) and 63% of similarly innervated muscles transferred for combined motion achieved at least Grade M4 elbow flexion strength.


Functioning free muscle transfer is a viable reconstructive option for restoration of upper-extremity function in the setting of severe BPI. It is possible to achieve good to excellent outcomes in terms of muscle grades with the simultaneous reconstruction of two functions by one FFMT, making restoration of basic hand function possible. More reliable results are obtained when a single FFMT is performed for a single function.

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Peroneal intraneural ganglia: the importance of the articular branch. A unifying theory

Robert J. Spinner, John L. D. Atkinson, and Robert L. Tiel

Object. Based on a large multicenter experience and a review of the literature, the authors propose a unifying theory to explain an articular origin of peroneal intraneural ganglia. They believe that this unifying theory explains certain intriguing, but poorly understood findings in the literature, including the proximity of the cyst to the joint, the unusual preferential deep peroneal nerve (DPN) deficit, the absence of a pure superficial peroneal nerve (SPN) involvement, the finding of a pedicle in 40% of cases, and the high (10–20%) recurrence rate.

Methods. The authors believe that peroneal intraneural lesions are derived from the superior tibiofibular joint and communicate from it via a one-way valve. Given access to the articular branch, the cyst typically dissects proximally by the path of least resistance within the epineurium and up the DPN and the DPN component of the common peroneal nerve (CPN) before compressing nearby SPN fascicles. The authors present objective evidence based on anatomical, clinical, imaging, operative, and histological data that support this unifying theory.

Conclusions. The predictable clinical presentation, electrical studies, imaging characteristics, operative observations, and histological findings regarding peroneal intraneural ganglia can be understood in terms of their origin from the superior tibiofibular joint, the anatomy of the articular branch, and the internal topography of the peroneal nerve that the cyst invades. Understanding the controversial pathogenesis of these cysts will enable surgeons to perform operations based on the pathoanatomy of the articular branch of the CPN and the superior tibiofibular joint, which will ultimately improve clinical results.

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Peroneal intraneural ganglia: the importance of the articular branch. Clinical series

Robert J. Spinner, John L. D. Atkinson, Bernd W. Scheithauer, Michael G. Rock, Rolfe Birch, Thomas A. Kim, Michel Kliot, David G. Kline, and Robert L. Tiel

Object. The peroneal nerve is the most common site of intraneural ganglia. The neurological deficit associated with these cysts is often severe and the operation to eradicate them is difficult. The aims of this multicenter study were to collate the authors' experience with a relatively rare lesion and to improve clinical outcomes by better understanding its controversial pathogenesis.

Methods. Part I of this paper offers a description of 24 patients with peroneal intraneural ganglia who were treated by surgeons aware of the importance of the peroneal nerve's articular branch. Part II offers a description of three more patients who were seen after earlier operations in which the ganglion was excised, but the articular branch was not identified (all reportedly gross-total resections). Twenty-six of the 27 patients presented with clinical, electrophysiological, and imaging evidence of a common peroneal nerve (CPN) lesion, predominantly affecting the deep peroneal nerve (DPN) division, and one patient presented with a painful mass of the CPN that was not accompanied by a neurological deficit.

In all 24 patients in Part I there was magnetic resonance (MR) imaging evidence of a connection between the cyst and the superior tibiofibular joint, including one patient in whom high-resolution (3-tesla) MR neurography demonstrated the pathological articular branch itself. At the operation, the communication proved to extend through the articular branch of the CPN in all cases. The operation consisted of drainage of the cyst and ligation of the articular branch. At a minimum follow-up period of 1 year, these patients experienced significant improvements in their neuropathic pain, but only mild improvements in their functional deficits. In none of the 24 patients was there evidence of an intraneural recurrence. In three patients, however, extraneural ganglia developed: two patients with symptoms subsequently underwent resection of the superior tibiofibular joint without further recurrence and one patient with no symptoms was followed clinically after the recurrence was detected incidentally on 1-year postoperative imaging. As predicted, in Part II all three patients in whom the articular branch had not been ligated experienced early intraneural recurrence; both postoperative MR images and original studies, which were retrospectively examined, demonstrated a connection with the superior tibiofibular joint.

Conclusions. The clinical presentation, electrical studies, imaging characteristics, and operative observations regarding peroneal intraneural ganglia are predictable. Treatment must address the underlying pathoanatomy and should include decompression of the cyst and ligation of the articular branch of the nerve. To avoid extraneural recurrence, resection of the superior tibiofibular joint may also be necessary, but indications for this additional procedure need to be defined. These recommendations are based on the authors' belief that intraneural peroneal ganglia arise from the superior tibiofibular joint and are connected to it by the articular branch.

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Neuromuscular choristoma of the sciatic nerve

Case report

Cormac O. Maher, Robert J. Spinner, Caterina Giannini, Bernd W. Scheithauer, and Brian A. Crum

✓ The authors report the findings of a neuromuscular choristoma of the sciatic nerve in an otherwise healthy 18-year-old man who presented with sensorimotor symptoms and deformities of the right leg and foot. Only a few cases of this rare tumor, also known as “neuromuscular hamartoma” or “benign triton tumor,” have been reported in the surgical literature. The authors discuss the clinical presentation, radiological findings, pathological diagnosis, and surgical rationale for this case and review the associated literature.