MR features of the denervated tongue in radiation induced neuropathy

Tongue and hypoglossal morphology after intralingual cholera toxin B-saporin injection

INTRODUCTION

We recently developed an inducible model of dysphagia using intralingual injection of cholera toxin B conjugated to saporin (CTB-SAP) to cause death of hypoglossal neurons. In this study we aimed to evaluate tongue morphology and ultrastructural changes in hypoglossal neurons and nerve fibers in this model.

METHODS

Tissues were collected from 20 rats (10 control and 10 CTB-SAP animals) on day 9 post-injection. Tongues were weighed, measured, and analyzed for microscopic changes using laminin immunohistochemistry. Hypoglossal neurons and axons were examined using transmission electron microscopy.

RESULTS

The cross-sectional area of myofibers in the posterior genioglossus was decreased in CTB-SAP-injected rats. Degenerative changes were observed in both the cell bodies and distal axons of hypoglossal neurons.

DISCUSSION

Preliminary results indicate this model may have translational application to a variety of neurodegenerative diseases resulting in tongue dysfunction and associated dysphagia.

Magnetic resonance imaging differentiates locoregional flaps from free flaps after reconstructive surgical treatment of tongue cancer

OBJECTIVE

The aim of this study was to compare magnetic resonance imaging (MRI) features of reconstruction with locoregional flaps (LRFs) with free flaps (FFs) after surgical treatment for tongue cancer.

STUDY DESIGN

In total, 115 cases of postoperative tongue carcinoma (67 cases of LRF surgery and 48 cases of FF surgery) were retrospectively reviewed. All patients had undergone nonenhanced and contrast-enhanced MRI at 0-4, 5-12, and 13-48 months after surgery. Signal intensity, margins, maximal size, contrast enhancement, change in the hyoglossus and mylohyoid muscles, recurrence, lymph node metastasis, and complications were evaluated.

RESULTS

Significant differences were found between LRF and FF for signal intensity (P < .001) in all 3 periods, with LRF mostly isointense with muscle on T1-weighted images (T1WIs) and FF producing mixed hyperintensity with muscular striations in all cases in T1WIs and T2-weighted images (T2 WIs). Margin definition was similar between groups in the early period, but sharp margins were more common in FF after 4 months (P ≤ .018). LRF was significantly smaller than FF in all periods (P ≤ .017). Both mylohyoid and hyoglossus enlargements were common in the early period in both groups, but all cases became atrophic later.

CONCLUSIONS

MRI can differentiate LRFs from FFs in a variety of parameters after flap reconstructive surgery for tongue cancer.

Delayed lower cranial neuropathy after oropharyngeal intensity-modulated radiotherapy: A cohort analysis and literature review

BACKGROUND

The purpose of this study was to examine swallowing-related lower cranial nerve palsy (LCNP) in oropharyngeal cancer (OPC) survivors after intensity-modulated radiotherapy (IMRT).

METHODS

Patients treated with definitive IMRT (66-72 Gy) were pooled from institutional trial databases. Prospective analyses on parent trials included videofluoroscopy, clinical LCNP examination, and questionnaires pre-IMRT, 6 months post-IMRT, 12 months post-IMRT, and 24 months post-IMRT. Time-to-event and incidence of LCNP was estimated with competing risk methods. Literature review (1977-2015) summarized published LCNP outcomes.

RESULTS

Three of 59 oropharyngeal cancer survivors with a minimum 2-year follow-up developed hypoglossal palsy ipsilateral to the index tumor (median latency 6.7 years; range 4.6-7.6 years). At a median of 5.7 years, cumulative incidence of LCNP was 5%. LCNP preceded progressive dysphagia in all cases. Published studies found median incidence of radiation-associated LCNP was 10.5% after NPC, but no OPC cancer-specific estimate.

CONCLUSION

Although uncommon, the potential for late LCNP preceding swallowing deterioration highlights the importance of long-term functional surveillance in OPC survivorship.

Inflammatory Myopathy with Severe Tongue Atrophy in Pembroke Welsh Corgi Dogs

A disease characterized by tongue and facial muscle atrophy has been recognized sporadically among Pembroke Welsh Corgi (PWC) dogs in Japan. The present study describes the pathologic findings of this canine syndrome. Histopathologic examinations were performed in 2 dogs, including a case of muscular biopsy. Identification and characterization of autoantibodies were attempted by fluorescent antibody test (FAT) and Western blot (WB) by using sera from 7 PWC dogs with typical clinical features, 6 PWC dogs with other clinical signs, and 2 from other breeds with polymyositis. Clinically, the 7 affected PWC dogs exhibited dysphagia with severe tongue atrophy, facial muscular atrophy, and occasional walking difficulty. Histopathologic examinations of the 2 dogs with clinical symptoms revealed moderate to severe inflammatory lesions characterized by lymphohistiocytic infiltration and muscular atrophy in the tongue and/or femoral muscles. The tongue lesions were very severe and accompanied by diffuse fatty infiltration. There were no major lesions in the nervous tissues examined. By FAT, an autoantibody against the cross striation of skeletal muscle was detected in sera from 5 affected PWC dogs. By using WB analysis, the autoantibodies recognized a 42-kDa molecule in striated muscle but not in the nervous tissues. All of the findings indicated that the unique disease of PWC dogs might be generalized inflammatory myopathy, whereas the detailed etiology concerning the dominant involvement of tongue muscles and the role of the autoantibody in the canine disease remain to be clarified.

Neurophysiological and histopathological evaluation of low-dose radiation on the cauda equina and postlaminotomy fibrosis: an experimental study in the rat

STUDY DESIGN

We evaluated the electrophysiological changes to the cauda equina after low-dose external irradiation in a postlaminotomy fibrosis model in rats.

OBJECTIVE

To clarify the immediate and long-term electrophysiological responses of antifibrotic radiation therapy in a fibrosis model.

SUMMARY OF BACKGROUND DATA

Low-dose perioperative radiation therapy inhibits scar formation. However, its efficacy for preventing fibrosis-induced compressive neuropathy and its potential adverse effect on underlying neural structures have not been studied.

METHODS

Twenty-four rats were placed in 3 groups of 8: group I, sham operation (laminar exposure alone) with a single fraction of 700 cGy external irradiation given using a 9-MeV electron beam 24 hours postsurgery; group II, left L5 hemilaminectomy (laminotomy) alone; and group III, left L5 hemilaminectomy with the same radiation protocol as group 1. We recorded mixed-nerve-elicited somatosensory-evoked potentials (M-SSEP)- and dermal (D)-SSEP at the thoracolumbar junction, and L1-L2 interspinous ligament after percutaneously stimulating the posterior tibial nerve at the bilateral medial ankle and L5 dermatomal fields. We compared the potentials recorded immediately before, 30 minutes, 2 weeks, and 1, 2, and 3 months after surgery on the operated and nonoperated sides. We used gross dissection and histologic sections to evaluate the degree of perineural fibrosis and walking-track analysis for neurologic evaluation.

RESULTS

Pre- and postoperative (30 minutes and 2 weeks) M- and D-SSEP were not statistically different. In group II, the relative amplitude of D-SSEP (elicited from 5 dermatomes) 1, 2, and 3 months postsurgery was lower; however, the M-SSEP in all groups and D-SSEP of groups I and III remained constant. Histologic evaluation of radiation efficacy showed that the frequency and extent of peridural fibrosis was consistently lower in group II than in group III.

CONCLUSION

Low-dose irradiation reduced peridural fibrosis and prevented fibrosis-induced radiculopathy. The radiation caused no adverse neuropathic complications.

Delayed complications of radiotherapy treatment for nasopharyngeal carcinoma: imaging findings

Radiotherapy is used to treat a wide variety of head and neck tumours that arise in and around the skull base. The delayed effects of radiation damages a range of structures, including the nervous system, bone, major vessels, mucus membranes, pituitary and salivary glands, as well as increasing the risk of radiation-induced neoplasms. In this review the complications resulting from radiation treatment for nasopharyngeal carcinoma (NPC), a cancer treated with a high dose of radiation to a fairly large region, are illustrated. Many patients with NPC have a long-term survival, so are at risk of developing delayed radiation effects, and hence may demonstrate a wide range of complications on imaging. Other tumours around the skull base treated with radiotherapy include meningiomas, chordomas, chondrosarcomas, pituitary adenomas, paranasal sinus and nasal cavity tumours. In these cases similar complications may be encountered on imaging, although the severity, incidence and location will vary.

Long-term functional outcome of brachytherapy for carcinoma of the mobile tongue: focus on the atrophic change of irradiated tongue

OBJECTIVE

To assess tongue atrophy and long-term functional outcome of mobile tongue cancer patients after interstitial radiotherapy.

METHODS

Of 493 patients whose squamous cell carcinoma of the mobile tongue had been treated with low dose rate brachytherapy, there were 57 patients evaluated between July 2002 and April 2004 whose tongue had not been modified by surgical procedures and who had no primary recurrence. The median time from treatment to evaluation was 96 months (range: 9-214 months). Almost all of the patients belonged to the early stage tongue cancer (T1/T2/T3/T4=30:24:3:0), and all had received interstitial radiotherapy with a single-plane implant. To evaluate the deformity of the tongue, we used a grading system that classified the atrophic changes of the tongue into four categories (G0-G3).

RESULTS

Thirty-nine patients (70%) showed mild tongue hemiatrophy (G1 or G2) in the irradiated side. However, no patients showed severe atrophy where the tongue cannot be made to protrude beyond the incisors (G3). The length of time after brachytherapy was >72 months and the age of the patients at brachytherapy had the same statistical significance (P=0.0366). As for functional outcome, understandability of speech and a normal diet were preserved for almost all patients.

CONCLUSION

The progression of atrophic change in the irradiated tongue occurred over a long term after brachytherapy. However, most patients could maintain their activities of daily life without severe restriction.

Imaging of muscular denervation secondary to motor cranial nerve dysfunction

The effects of motor cranial nerve dysfunction on the computed tomography (CT) and magnetic resonance imaging (MRI) appearances of head and neck muscles are reviewed. Patterns of denervation changes are described and illustrated for V, VII, X, XI and XII cranial nerves. Recognition of the range of imaging manifestations, including the temporal changes in muscular appearances and associated muscular grafting or compensatory hypertrophy, will avoid misinterpretation as local disease. It will also prompt the radiologist to search for underlying cranial nerve pathology, which may be clinically occult. The relevant cranial nerve motor division anatomy will be described to enable a focussed search for such a structural abnormality.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach.Advances in pretherapeutic imaging have significantly contributed to the managementof sinonasal tumors. CT and MR imaging play complementary roles in the assess-mentand staging of these malignancies by determining the presence or absence of exten-sionof disease into the skull base and its foramina, the orbit, and the intracranial compartment.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach. Advances in pretherapeutic imaging have significantly contributed to the management of sinonasal tumors. CT and MR imaging play complementary roles in the assessment and staging of these malignancies by determining the presence or absence of extension of disease into the skull base and its foramina, the orbit, and the intracranial compartment.

Radiation-related cranial nerve palsy in patients with nasopharyngeal carcinoma

BACKGROUND

Cranial nerve palsy is a rare complication after patients with nasopharyngeal carcinoma (NPC) receive radiotherapy using a technique that delivers 180-200 centigrays (cGy) per day. Cranial neuropathy is of particular clinical interest in terms of making a differential diagnosis, because it is also a common presenting manifestation in patients with NPC. Cranial neuropathy may lead to distressing signs and symptoms in these patients, and their treatment has not been addressed in previous reports. This article presents the authors' experience with radiotherapy-related cranial nerve palsy in patients with NPC.

METHODS

Nineteen patients were diagnosed with radiation-related neuropathy. Patients with recurrent tumors or with a suspicion of persistent or recurrent tumors were excluded. Most patients were treated using 180 cGy or 200 cGy per fraction per day. The total dose was 7000-13,000 cGy to the nasopharynx and 5000-9000 cGy to the neck. Unilateral vocal cord paralysis alone and hearing loss were not included in the analysis.

RESULTS

There were 15 male patients and 4 female patients. The latency before palsy occurred was 12-240 months. Single nerve palsy developed in four patients, including two patients with hypoglossal palsy and two patients with recurrent laryngeal palsy. Two patients had three nerve palsies each. The other 13 patients presented with 2 nerve palsies each. Vagus and hypoglossal palsy appeared to be a frequent combination and occurred in 11 patients. Overall, there were 17 patients with hypoglossal palsy (7 bilateral, 8 left-sided, and 2 right-sided), 11 patients with vagus palsy (2 bilateral, 7 left-sided, and 2 right-sided), 6 patients with recurrent laryngeal nerve palsy (5 bilateral), and 2 patients with accessory palsies (all bilateral). Marked neck fibrosis was present in 12 patients. Patients who had vocal cord paralysis suffered from easy choking and hoarseness. Severe respiratory difficulty occurred in two patients who had bilateral vocal cord palsy. Surgical procedures included laryngoplasty, tracheostomy, and gastrostomy. Quality of life improved considerably after patients underwent surgery.

CONCLUSIONS

Radiotherapy-related cranial nerve palsy may occur in patients with NPC after they receive conventional radiotherapy. Hypoglossal nerve palsy was found the most frequently in this series, followed by vagus nerve palsy and recurrent laryngeal nerve palsy. Neck fibrosis and the course of the three nerves through the neck may be important risk factors for the development of palsy. The diagnosis must be made only after the possibilities of tumor-induced palsy and idiopathic palsy are excluded. Surgery is helpful in improving the quality of life in many patients.