Schwannoma del nervio tibial en un paciente con schwannomatosis asociada a una nueva mutación en el gen LZTR1 / Schwannoma of the posterior tibial nerve in a patient with schwannomatosis and a novel mutation of the LZTR1 gene

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CT can stratify patients as low risk for tibial neuropathy following a talus fracture.

OBJECTIVE: Determine the incidence of tibial neuropathy following talus fractures and CT's ability to stratify patients at risk for developing post-traumatic neuropathy. MATERIALS AND METHODS: In this IRB-approved retrospective analysis, 71 talus fractures and 8 contralateral control ankle CTs were reviewed by one observer blinded to clinical information. CT evidence suggestive of tibial neurovascular bundle injury included nerve displacement, perineural fat effacement/edema, and bone touching nerve. The association between these CT findings and clinically evident tibial neuropathy was analyzed. A semi-quantitative likelihood score was assigned based on the degree of the CT findings around the nerve. Interobserver agreement was calculated between 2 other readers. RESULTS: Twenty-five percent of patients in this cohort had clinical evidence of tibial neuropathy. There was a high specificity (0.87-0.93) and negative predictive value (0.83-0.87), a moderate accuracy (0.80-0.82), but a lower sensitivity (0.33-0.56) associated with the CT findings. Among the CT findings, nerve displacement (p < 0.0001) and bone touching nerve (p = 0.01) were associated with tibial neuropathy. A likelihood score of 2-5 was associated (p = 0.007-0.015) with tibial neuropathy. The presence of tibial neuropathy and nerve recovery were not associated with hospital length of stay, while CT findings were. There was substantial agreement between the three readers: likelihood scores 2+ (k = 0.78) and 3+ (k = 0.72). CONCLUSIONS: Tibial neuropathy occurs following talus fractures, and CT findings may help surgeons narrow down the number of patients requiring close neurological follow-up.

Tibial Nerve Palsy After Lateralizing Calcaneal Osteotomy.

Background: Lateralizing calcaneal osteotomy (LCO) is a common procedure used to correct hindfoot varus. Several complications have been described in the literature, but only a few articles describe tibial nerve palsy after this procedure. Our hypothesis was that tibial nerve palsy is a common complication after LCO. Methods: A retrospective study of patients undergoing LCO for hindfoot varus between 2007 and 2013 was performed. A total of 15 patients (18 feet) were included in the study. The patients were examined for tibial nerve deficit, and all the patients were examined with a computed tomography (CT) scan of both feet. Patients with a preexisting neurological disease were excluded. The primary outcome was tibial nerve palsy, and the secondary outcomes were reduction of the tarsal tunnel volume, the distance from subtalar joint to the osteotomy, and the lateral step at the osteotomy evaluated by CT scans. Results: Three of the 18 feet examined had tibial nerve palsy at a mean follow-up of 51 months. The mean reduction in tarsal tunnel volume when comparing the contralateral nonoperated foot to the foot operated with LCO was 2732 mm3 in the group without neurological deficit and 2152 mm3 in the group with neurological deficit (P = .60). Conclusion: 3 of 18 feet had tibial palsy as a complication to LCO. We were not able to show that a larger decrease in the tarsal tunnel volume, a more anterior calcaneal osteotomy, or a larger lateral shift of the osteotomy is associated with tibial nerve palsy. Levels of Evidence: Level IV: Retrospective case series.

A rare case of an acute soleus arcade syndrome complicated by a ganglion cyst: diagnosis by dynamic ultrasound.

The soleus arcade syndrome is a rare compression neuropathy of the tibial nerve that often remains undiagnosed due to low clinical awareness and difficult diagnosis. We present the case of a female patient admitted with acute worsening of a pre-existing sensory tibial neuropathy and acute tibial nerve palsy after knee joint injection. After a knee magnetic resonance imaging remained non-diagnostic, dynamic ultrasonography was performed. Constriction by the soleus arcade and proximal swelling of the tibial nerve could be demonstrated during plantarflexion of the ankle by means of a dynamic examination in the standing patient. The patient underwent surgery and recovered fully. This proposed diagnostic approach can be used to identify soleus arcade syndrome by ultrasound.

Ultrasound Imaging for Posterior Knee Pain: Tibial Nerve Schwannoma Not Popliteus Muscle Strain.

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Radioguided Occult Lesion Localization in Deep Schwannomas of the Peripheral Nerves: Results of a Preliminary Case Series.

BACKGROUND: The detection of small deep schwannomas of the peripheral nerves has been increasing since the the use of precise neuroimaging techniques has become more widespread; however, although nonpalpable lesions can be well defined by images, it is often difficult to identify them during the surgical procedure. The authors report seven cases of nonpalpable small deep schwannomas surgically treated after their identification using the radioguided occult lesion localization (ROLL) technique. METHODS: Seven men, whose ages ranged from 34 to 70 years (mean 52 years), presented with symptomatic nonpalpable peripheral nerve lesions; two cases involved the sciatic nerve, two the femoral nerve, two the radial nerve, and one the tibial nerve. Before the operation, all the patients were studied by ultrasonography and magnetic resonance imaging (MRI); 1 h before the surgery 3-5 MBq of 99mTc labeled with human albumin macroaggregates was injected into the lesion. A gamma detection probe permitted the preoperative and intraoperative detection of the nonpalpable schwannomas. CONCLUSIONS: The ROLL technique provides good support for identifying small lesions of the peripheral nerves both preoperatively and intraoperatively. This technique permits the use of minimally invasive approaches performed with local anesthesia, with good cosmetic results and acceptance by the patients.

Metabolic brain activity suggestive of persistent pain in a rat model of neuropathic pain.

Persistent pain is a central characteristic of neuropathic pain conditions in humans. Knowing whether rodent models of neuropathic pain produce persistent pain is therefore crucial to their translational applicability. We investigated the spared nerve injury (SNI) model of neuropathic pain and the formalin pain model in rats using positron emission tomography (PET) with the metabolic tracer [18F]fluorodeoxyglucose (FDG) to determine if there is ongoing brain activity suggestive of persistent pain. For the formalin model, under brief anesthesia we injected one hindpaw with 5% formalin and the FDG tracer into a tail vein. We then allowed the animals to awaken and observed pain behavior for 30min during the FDG uptake period. The rat was then anesthetized and placed in the scanner for static image acquisition, which took place between minutes 45 and 75 post-tracer injection. A single reference rat brain magnetic resonance image (MRI) was used to align the PET images with the Paxinos and Watson rat brain atlas. Increased glucose metabolism was observed in the somatosensory region associated with the injection site (S1 hindlimb contralateral), S1 jaw/upper lip and cingulate cortex. Decreases were observed in the prelimbic cortex and hippocampus. Second, SNI rats were scanned 3weeks post-surgery using the same scanning paradigm, and region-of-interest analyses revealed increased metabolic activity in the contralateral S1 hindlimb. Finally, a second cohort of SNI rats was scanned while anesthetized during the tracer uptake period, and the S1 hindlimb increase was not observed. Increased brain activity in the somatosensory cortex of SNI rats resembled the activity produced with the injection of formalin, suggesting that the SNI model may produce persistent pain. The lack of increased activity in S1 hindlimb with general anesthetic demonstrates that this effect can be blocked, as well as highlights the importance of investigating brain activity in awake and behaving rodents.

Sonographic visualization of the first branch of the lateral plantar nerve (baxter nerve): technique and validation using perineural injections in a cadaveric model.

OBJECTIVES: The primary purpose of this investigation was to document the ability of high-resolution sonography to accurately identify the first branch of the lateral plantar nerve (FBLPN) using sonographically guided perineural injections in an unembalmed cadaveric model. METHODS: single experienced operator completed sonographically guided perineural FBLPN injections in 12 unembalmed cadaveric specimens (6 right and 6 left) obtained from 10 donors (5 male and 5 female) aged 47 to 95 years (mean, 71 years) with an average body mass index of 24.2 kg/m(2) (range, 17.2-31.6 kg/m(2)). All injections were completed using 22-gauge, 38-mm stainless steel needles to deliver 1 mL of 50% diluted colored latex adjacent to the FBLPN in the abductor hallucis-quadratus plantae (AH-QP) interval. Six injections were completed using a cart-based ultrasound (US) machine and a 17-5-MHz transducer, and 6 were completed using a portable US machine and a 12-3-MHz transducer. Nerve conspicuity was graded on a 4-point scale (1, poor; 4, excellent). After a minimum of 24 hours, study coinvestigators dissected each specimen to assess injectate placement. RESULTS: All 12 injections accurately placed latex onto the FBLPN within the AH-QP interval, with 11 of 12 (91%) resulting in complete nerve coverage. Proximal latex overflow to the lateral plantar nerve occurred in 82% of cases (10 of 12). The average distance between the plantar fascia and injected latex was 1.2 cm (range, 1.0-1.75 cm). No vascular injury was seen in any specimen. The average nerve conspicuities were 3.7 (range, 3-4) using the cart-based US machine and 1.8 (range, 1-4) using the portable US machine. CONCLUSIONS: Sonographic visualization of the FBLPN in the AH-QP interval is feasible and should be considered for diagnostic and therapeutic purposes in patients presenting with chronic or atypical heel pain syndromes. Further clinical experience should refine the role of FBLPN sonography and explore the utility of sonographically guided diagnostic and therapeutic FBLPN perineural injections.

Peroneal and tibial intraneural ganglia: correlation between intraepineurial compartments observed on magnetic resonance images and the potential importance of these compartments.

OBJECT: Previously the authors demonstrated that peroneal and tibial intraneural ganglia arising from the superior tibiofibular joint may occasionally extend proximally within the epineurium to reach the sciatic nerve. The dynamic nature of these cysts, dependent on intraarticular pressures, may give rise to differing clinical and imaging presentations that have remained unexplained until now. To identify the pathogenesis of these unusual cysts and to correlate their atypical magnetic resonance (MR) imaging appearance, the authors retrospectively reviewed their own experience as well as the published literature on these types of intraneural ganglia. METHODS: A careful review of MR images obtained in 22 patients with intraneural ganglia located about the knee region (18 peroneal and four tibial intraneural ganglia) allowed the authors to substantiate three different patterns: outer (epifascicular) epineurial (20 cases); inner (interfascicular) epineurial (one case); and combined outer and inner epineurial (one case). In these cases serial MR images allowed the investigators to track the movement of the cyst within the same layer of the epineurium. All lesions had connections to the superior tibiofibular joint. Nine patients were identified as having lesions with sciatic nerve extension. Seven patients harboring an outer epineurial cyst (six in whom the cyst involved the peroneal nerve and one in whom it involved the tibial nerve) had signs of sciatic nerve cross-over, with the cyst seen in the sciatic nerve and/or other terminal branches. In only two of these cases had the cyst previously been recognized to have sciatic nerve involvement. In contrast, in one case an inner epineurial cyst involving the tibial nerve ascended within the tibial division of the sciatic nerve and did not cross over. A single patient had a combination of both outer and inner epineurial cysts; these were easily distinguished by their distinctive imaging patterns. CONCLUSIONS: This anatomical compartmentalization of intraneural cysts can be used to explain varied clinical and imaging patterns of cleavage planes for cyst formation and propagation. Compartmentalization elucidates the mechanism for cases of outer epineurial cysts in which there are primary ascent, sciatic cross-over, and descent of the lesion down terminal branches; correlates these cysts' atypical MR imaging features; and contrasts a different pattern of inner epineurial cysts in which ascent and descent occur without cross-over. The authors present data demonstrating that the dynamic phases of these intraneural ganglia frequently involve the sciatic nerve. Their imaging features are subtle and serve to explain the underrecognition and underreporting of the longitudinal extension of these cysts. Importantly, cysts extending to the sciatic nerve are still derived from the superior tibiofibular joint. Combined with the authors' previous experimental data, the current observations help the reader understand intraneural ganglia with a different, deeper degree of anatomical detail.

Ultrasonography of the tibial nerve in vasculitic neuropathy.

Ultrasonography is a new imaging method for visualizing peripheral nerves. In vasculitic neuropathy, pain or axonopathy often can prevent the lesion from being localized during electrophysiological examinations, but the ability of ultrasonography to evaluate it morphologically is unknown. Our aim was to determine whether ultrasonography could be used to detect abnormalities in tibial vasculitic neuropathy at the medial ankle. We evaluated 11 tibial nerves in 8 patients with tibial vasculitic neuropathy, and 35 tibial nerves in 35 control subjects. In the controls, the tibial nerve was successfully visualized as a hyperechoic nodule with multiple round hypoechoic areas transversely; in the patients, the tibial nerve appeared enlarged and hypoechoic. The affected nerve area was significantly larger (13.5 +/- 3.7 mm(2)) than in controls (7.2 +/- 1.5 mm(2)). Our results suggest that ultrasonography is a useful neuroimaging method for evaluation of tibial vasculitic neuropathy, especially when nerve conduction study findings are inconclusive.