Compressive epidural collection as an unusual complication of FESS for a pediatric mycetoma.

Functional endoscopic sinus surgery (FESS) is a treatment of choice for fungal sinus ball (mycetoma), which is considered safe with a very low major complication rate. We present an unusual case of a 12-year-old female, who underwent FESS for a sphenoid sinus mycetoma and which was complicated by an acute, compressive epidural fluid collection. This presumably resulted from sinus irrigation in the setting of an under-appreciated skull base and mucosal defects causing a ball-valve effect. Our patient had a temporary neurologic deficit with complete recovery, however, similar complications can have fatal consequences.

A systematic review of endovascular stent-electrode arrays, a minimally invasive approach to brain-machine interfaces.

OBJECTIVE: The goal of this study was to systematically review the feasibility and safety of minimally invasive neurovascular approaches to brain-machine interfaces (BMIs). METHODS: A systematic literature review was performed using the PubMed database for studies published between 1986 and 2019. All studies assessing endovascular neural interfaces were included. Additional studies were selected based on review of references of selected articles and review articles. RESULTS: Of the 53 total articles identified in the original literature search, 12 studies were ultimately selected. An additional 10 articles were included from other sources, resulting in a total of 22 studies included in this systematic review. This includes primarily preclinical studies comparing endovascular electrode recordings with subdural and epidural electrodes, as well as studies evaluating stent-electrode gauge and material type. In addition, several clinical studies are also included. CONCLUSIONS: Endovascular stent-electrode arrays provide a minimally invasive approach to BMIs. Stent-electrode placement has been shown to be both efficacious and safe, although further data are necessary to draw comparisons between subdural and epidural electrode measurements given the heterogeneity of the studies included. Greater access to deep-seated brain regions is now more feasible with stent-electrode arrays; however, further validation is needed in large clinical trials to optimize this neural interface. This includes the determination of ideal electrode material type, venous versus arterial approaches, the feasibility of deep brain stimulation, and more streamlined computational decoding techniques.

Mathematical model of perineural tumor spread: a pilot study.

BACKGROUND: Perineural spread (PNS) of pelvic cancer along the lumbosacral plexus is an emerging explanation for neoplastic lumbosacral plexopathy (nLSP) and an underestimated source of patient morbidity and mortality. Despite the increased incidence of PNS, these patients are often times a clinical conundrum-to diagnose and to treat. Building on previous results in modeling glioblastoma multiforme (GBM), we present a mathematical model for predicting the course and extent of the PNS of recurrent tumors. METHODS: We created three-dimensional models of perineurally spreading tumor along the lumbosacral plexus from consecutive magnetic resonance imaging scans of two patients (one each with prostate cancer and cervical cancer). We adapted and applied a previously reported mathematical model of GBM to progression of tumor growth along the nerves on an anatomical model obtained from a healthy subject. RESULTS: We were able to successfully model and visualize perineurally spreading pelvic cancer in two patients; average growth rates were 60.7 mm/year for subject 1 and 129 mm/year for subject 2. The model correlated well with extent of PNS on MRI scans at given time points. CONCLUSIONS: This is the first attempt to model perineural tumor spread and we believe that it provides a glimpse into the future of disease progression monitoring. Every tumor and every patient are different, and the possibility to report treatment response using a unified scale-as "days gained"-will be a necessity in the era of individualized medicine. We hope our work will serve as a springboard for future connections between mathematics and medicine.

Targeted fascicular biopsy of the brachial plexus: rationale and operative technique.

OBJECTIVE Nerve biopsy is useful in the management of neuromuscular disorders and is commonly performed in distal, noncritical cutaneous nerves. In general, these procedures are diagnostic in only 20%-50%. In selected cases in which preoperative evaluation points toward a more localized process, targeted biopsy would likely improve diagnostic yield. The authors report their experience with targeted fascicular biopsy of the brachial plexus and provide a description of the operative technique. METHODS All cases of targeted biopsy of the brachial plexus biopsy performed between 2003 and 2015 were reviewed. Targeted nerve biopsy was performed using a supraclavicular, infraclavicular, or proximal medial arm approach. Demographic data and clinical presentation as well as the details of the procedure, adverse events (temporary or permanent), and final pathological findings were recorded. RESULTS Brachial plexus biopsy was performed in 74 patients (47 women and 27 men). The patients' mean age was 57.7 years. All patients had abnormal findings on physical examination, electrodiagnostic studies, and MRI. The overall diagnostic yield of biopsy was 74.3% (n = 55). The most common diagnoses included inflammatory demyelination (19), breast carcinoma (17), neurolymphomatosis (8), and perineurioma (7). There was a 19% complication rate; most of the complications were minor or transient, but 4 patients (5.4%) had increased numbness and 3 (4.0%) had additional weakness following biopsy. CONCLUSIONS Targeted fascicular biopsy of the brachial plexus is an effective diagnostic procedure, and in highly selected cases should be considered as the initial procedure over nontargeted, distal cutaneous nerve biopsy. Using MRI to guide the location of a fascicular biopsy, the authors found this technique to produce a higher diagnostic yield than historical norms as well as providing justification for definitive treatment.

Sequential imaging of intraneural sciatic nerve endometriosis provides insight into symptoms of cyclical sciatica.

Endometriosis of the nerve often remains an elusive diagnosis. We report the first case of intraneural lumbosacral plexus endometriosis with sequential imaging at different phases of the menstrual cycle: during the luteal phase and menstruation. Compared to the first examination, the examination performed during the patient's period revealed the lumbosacral plexus larger and hyperintense on T2-weighted imaging. The intraneural endometriosis cyst was also larger and showed recent hemorrhage. Additionally, this case represents another example of perineural spread of endometriosis from the uterus to the lumbosacral plexus along the autonomic nerves and then distally to the sciatic nerve and proximally to the spinal nerves.

Targeted fascicular biopsy of the sciatic nerve and its major branches: rationale and operative technique.

OBJECT Nerve biopsy is typically performed in distal, noncritical sensory nerves without using imaging to target the more involved regions. The yield of these procedures rarely achieves more than 50%. In selected cases where preoperative evaluation points toward a more localized (usually a more proximal) process, targeted biopsy would likely capture the disease. Synthesis of data obtained from clinical examination, electrophysiological testing, and MRI allows biopsy of a portion of the major mixed nerves safely and efficiently. Herein, experiences with the sciatic nerve are reported and a description of the operative technique is provided. METHODS All cases of sciatic nerve biopsy performed between 2000 and 2014 were reviewed. Only cases of fascicular nerve biopsy approached from the buttock or the posterior aspect of the thigh were included. Demographic data, clinical presentation, and the presence of percussion tenderness for each patient were recorded. Reviewed studies included electrodiagnostic tests and imaging. Previous nerve and muscle biopsies were noted. All details of the procedure, final pathology, and its treatment implications were recorded. The complication rate was carefully assessed for temporary as well as permanent complications. RESULTS One hundred twelve cases (63 men and 49 women) of sciatic nerve biopsy were performed. Mean patient age was 46.4 years. Seventy-seven (68.8%) patients presented with single lower-extremity symptoms, 16 (14.3%) with bilateral lower-extremity symptoms, and 19 (17%) with generalized symptoms. No patient had normal findings on physical examination. All patients underwent electrodiagnostic studies, the findings of which were abnormal in 110 (98.2%) patients. MRI was available for all patients and was read as pathological in 111 (99.1%). The overall diagnostic yield of biopsy was 84.8% (n = 95). The pathological diagnoses included inflammatory demyelination, perineurioma, nonspecific inflammatory changes, neurolymphomatosis, amyloidosis, prostate cancer, injury neuroma, neuromuscular choristoma, sarcoidosis, vasculitis, hemangiomatosis, arteriovenous malformation, fibrolipomatous hamartoma (lipomatosis of nerve), and cervical adenocarcinoma. The series included 11 (9.9%) temporary and 5 (4.5%) permanent complications: 3 patients (2.7%) reported permanent numbness in the peroneal division distribution, and 2 patients (1.8%) were diagnosed with neuromuscular choristoma that developed desmoid tumor at the biopsy site 3 and 8 years later. CONCLUSIONS Targeted fascicular biopsy of the sciatic nerve is a safe and efficient diagnostic procedure, and in highly selected cases can be offered as the initial procedure over distal cutaneous nerve biopsy. Diagnoses were very diverse and included entities considered very rare. Even for the more prevalent diagnoses, the biopsy technique allowed a more targeted approach with a higher diagnostic yield and justification for more aggressive treatment. In this series, new radiological patterns of some entities were identified, which could be biopsied less frequently.

Perineural spread of pelvic malignancies to the lumbosacral plexus and beyond: clinical and imaging patterns.

OBJECT Perineural spread along pelvic autonomie nerves has emerged as a logical, anatomical explanation for selected cases of neoplastic lumbosacral plexopathy (LSP) in patients with prostate, bladder, rectal, and cervical cancer. The authors wondered whether common radiological and clinical patterns shared by various types of pelvic cancer exist. METHODS The authors retrospectively reviewed their institutional series of 17 cases concluded as perineural tumor spread. All available history, physical examination, electrodiagnostic studies, biopsy data and imaging studies, evidence of other metastatic disease, and follow-up were recorded in detail. The series was divided into 2 groups: cases with neoplastic lumbosacral plexopathy confirmed by biopsy (Group A) and cases included based on imaging characteristics despite the lack of biopsy or negative biopsy results (Group B). RESULTS Group A comprised 10 patients (mean age 69 years); 9 patients were symptomatic and 1 was asymptomatic. The L5-S1 spinal nerves and sciatic nerve were most frequently involved. Three patients had intradural extension. Seven patients were alive at last follow-up. Group B consisted of 7 patients (mean age 64 years); 4 patients were symptomatic, 2 were asymptomatic, and 1 had only imaging available. The L5-S1 spinal nerves and the sciatic nerve were most frequently involved. No patients had intradural extension. Four patients were alive at last follow-up. CONCLUSIONS The authors provide a unifying theory to explain lumbosacral plexopathy in select cases of various pelvic neoplasms. The tumor cells can use splanchnic nerves as conduits and spread from the end organ to the lumbosacral plexus. Tumor can continue to spread along osseous and muscle nerve branches, resulting in muscle and bone "metastases." Radiological studies show a reproducible, although nonspecific pattern, and the same applies to clinical presentation.

Perineural spread in pelvic malignancies can be an alternate explanation for pelvic bony metastases rather than hematogenous spread. A report of two cases.

We propose that pelvic malignancies can spread to bone and cause bony metastases using nerves as conduits. We reviewed two cases of pelvic malignancy with perineural spread of bladder cancer and prostate cancer. In a patient with prostate cancer, we identified six lesions that were positive on the (11)C-choline PET/CT scan and MRI; in a patient with bladder cancer, we identified two lesions positive on the (18)F-deoxy-glucose PET/CT scan and MRI. We carefully reviewed the imaging studies, and using established sclerotome maps we identified spinal nerves supplying each of eight pelvic bony lesions. All these spinal nerves showed evidence of tumor infiltration with extension toward the affected bones. We theorize that perineural tumor spread may serve as an additional mechanism of pelvic osseous metastases in pelvic malignancies.

Magnetic resonance imaging evidence for perineural spread of endometriosis to the lumbosacral plexus: report of 2 cases.

Sciatic nerve endometriosis (EM) is a rare presentation of retroperitoneal EM. The authors present 2 cases of catamenial sciatica diagnosed as sciatic nerve EM. They propose that both cases can be explained by perineural spread of EM from the uterus to the sacral plexus along the pelvic autonomie nerves and then further distally to the sciatic nerve or proximally to the spinal nerves. This explanation is supported by MRI evidence in both cases. As a proof of concept, the authors retrieved and analyzed the original MRI studies of a case reported in the literature and found a similar pattern of spread. They believe that the imaging evidence of their institutional cases together with the outside case is a very compelling indication for perineural spread as a mechanism of EM of the nerve.

Tumefactive appearance of peripheral nerve involvement in hematologic malignancies: a new imaging association.

OBJECTIVE: In neurolymphomatosis (NL), the affected nerves are typically described to be enlarged and hyperintense on T2W MR sequences and to avidly enhance on gadolinium-enhanced T1WI. This pattern is highly non-specific. We recently became aware of a "tumefactive pattern" of NL, neuroleukemiosis (NLK) and neuroplasmacytoma (NPLC), which we believe is exclusive to hematologic diseases affecting peripheral nerves. MATERIALS AND METHODS: We defined a "tumefactive" appearance as complex, fusiform, hyperintense on T2WI, circumferential tumor masses encasing the involved peripheral nerves. The nerves appear to be infiltrated by the tumor. Both structures show varying levels of homogenous enhancement. We reviewed our series of 52 cases of NL in search of this pattern; two extra outside cases of NL, three cases of NLK, and one case of NPLC were added to the series. RESULTS: We identified 20 tumefactive lesions in 18 patients (14 NL, three NLK, one NPLC). The brachial plexus (n = 7) was most commonly affected, followed by the sciatic nerve (n = 6) and lumbosacral plexus (n = 3). Four patients had involvement of other nerves. All were proven by biopsy: the diagnosis was high-grade lymphoma (n = 12), low-grade lymphoma (n = 3), acute leukemia (n = 2), and plasmacytoma (n = 1). CONCLUSIONS: We present a new imaging pattern of "tumefactive" neurolymphomatosis, neuroleukemiosis, or neuroplasmacytoma in a series of 18 cases. We believe this pattern is associated with hematologic diseases directly involving the peripheral nerves. Knowledge of this association can provide a clue to clinicians in establishing the correct diagnosis. Bearing in mind that tumefactive NL, NLK, and NPLC is a newly introduced imaging pattern, we still recommend to biopsy patients with suspicion of a malignancy.