Magnetic resonance imaging in brachial plexopathy of cancer

Electromyography findings in radiation-induced unilateral tongue immobility

BACKGROUND

We used electromyography to characterize hypoglossal nerve function among radiation-treated head and neck cancer survivors with later onset unilateral tongue immobility.

METHODS

Patients with unilateral tongue immobility without evidence of recurrent cancer were seen at a tertiary academic institution between February and September 2021. All patients were at least 2 years post-treatment with radiation therapy for head and neck squamous cell carcinoma. Participants were under annual surveillance and displayed no evidence of operative injury to the hypoglossal nerve.

RESULTS

The median symptom-free interval for the 10 patients included in this study was 13.2 years (range 2-25 years). Myokymia alone was present in 3 of 10 patients, fibrillation potentials alone were present in 3 of 10 patients, and 1 subject displayed both fibrillation and myokymia. Three out of 10 patients had normal hypoglossal nerve function.

DISCUSSION

These findings highlight how disparate mechanisms may underlie similar clinical presentations of radiation-induced neuromuscular dysfunction.

Brachial Plexus Magnetic Resonance Neurography: Technical Challenges and Solutions

ABSTRACT

Magnetic resonance neurography of the brachial plexus (BP) is challenging owing to its complex anatomy and technical obstacles around this anatomic region. Magnetic resonance techniques to improve image quality center around increasing nerve-to-background contrast ratio and mitigating imaging artifacts. General considerations include unilateral imaging of the BP at 3.0 T, appropriate selection and placement of surface coils, and optimization of pulse sequences. Technical considerations to improve nerve conspicuity include fat, vascular, and respiratory artifact suppression techniques; metal artifact reduction techniques; and 3-dimensional sequences. Specific optimization of these techniques for BP magnetic resonance neurography greatly improves image quality and diagnostic confidence to help guide nonoperative and operative management.

Stereotactic body radiotherapy for apical lung tumors: Dosimetric analysis of the brachial plexus and preliminary clinical outcomes

BACKGROUND

Dosimetric constraints of the brachial plexus have not yet been well-established for patients undergoing stereotactic body radiotherapy (SBRT). This study evaluated long-term experience with the treatment of early stage apical lung tumors with SBRT and reports on dosimetric correlates of outcome.

METHODS

Between 2009 and 2018, a total of 78 consecutive patients with 81 apical lung tumors underwent SBRT for T1-3N0 non-small cell lung cancer. Apical tumors were those with tumor epicenter superior to the aortic arch. The brachial plexus (BP) was anatomically contoured according to the Radiation Therapy Oncology Group (RTOG) atlas. Patient medical records were retrospectively reviewed to determine incidence of brachial plexus injury (BPI) and a normal tissue complication probability model (NTCP) was applied to the dosimetric data.

RESULTS

Five patients (6.4%) reported neuropathic symptoms consistent with BPI and occurred a median 11.9 months after treatment (range, 5.2 to 28.1 months). Most common dose and fractionation in those developing BPI were 50 Gy in 5 fractions (4 patients). Symptoms consisted of pain in 2 patients (40.0%), numbness in the hand or axilla in 4 patients (80.0%), and ipsilateral hand weakness in 1 patient (20.0%). In the overall cohort the median BP Dmax (EQD2_{3 Gy}) was 5.13 Gy (range, 0.18 to 217.2 Gy) and in patients with BPI the median BP Dmax (EQD2_{3 Gy}) was 32.14 Gy (range, 13.4 to 99.9 Gy). The NTCP model gave good fit with an area under the curve (AUC) of 0.75 (OR 7.3, 95% CI: 0.8-68.3) for BP Dmax (EQD2_{3 Gy}) threshold of 20 Gy.

CONCLUSION

Significant variation exists in the dose delivered to the brachial plexus for patients treated by SBRT for apical lung tumors. The incidence of neuropathic symptoms in the post-SBRT setting was appreciable and prospective clinical correlation with dosimetric information should be utilized in order to develop evidence-based dose constraints.

MR neurography of the brachial plexus in adult and pediatric age groups: evolution, recent advances, and future directions

Introduction: MR neurography (MRN) of the brachial plexus has emerged in recent years as a safe and accurate modality for the identification of brachial plexopathies in pediatric and adult populations. While clinical differentiation of brachial plexopathy from cervical spine-related radiculopathy or nerve injury has long relied upon nonspecific physical exam and electrodiagnostic testing modalities, MRN now permits detailed interrogation of peripheral nerve anatomy and pathology, as well as assessment of surrounding soft tissues and musculature, thereby facilitating accurate diagnosis. The reader will learn about the current state of brachial plexus MRN, including recent advances and future directions, and gain knowledge about the adult and pediatric brachial plexopathies that can be characterized using these techniques.Areas Covered: The review details recent developments in brachial plexus MRN, including increasing availability of 3.0-T MR scanners at both private and academic diagnostic imaging centers, as well as the advent of multiple new vascular and fat signal suppression techniques. A literature search of PubMed and SCOPUS was used as the principal source of information gathered for this review.Expert Opinion: Refinement of fat-suppression, 3D techniques and diffusion MR imaging modalities has improved the accuracy of MRN, rendering it as a useful adjunct to clinical findings during the evaluation of suspected brachial plexus lesions.

ACR Appropriateness Criteria® Plexopathy

MRI without and with contrast is the most accurate imaging method to determine whether a process is intrinsic or extrinsic to a nerve of the brachial or lumbosacral plexus. However, there are no Current Procedural Terminology codes to correspond to imaging studies of the brachial or lumbar plexus discretely. This assessment uses "MRI of the brachial plexus" or "MRI of the lumbosacral plexus" as independent entities given that imaging acquisition for the respective plexus differs in sequences and planes compared with those of a routine neck, chest, spine, or pelvic MRI, yet acknowledges the potential variability of ordering practices across institutions. In patients unable to undergo MRI, CT offers the next highest level of anatomic evaluation. In oncologic patients, PET/CT imaging can identify the extent of tumor involvement and be beneficial to differentiate radiation plexitis from tumor recurrence but provides limited resolution of the plexus itself. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Plexus and peripheral nerve metastasis

Cancer in the form of solid tumors, leukemia, and lymphoma can infiltrate and metastasize to the peripheral nervous system, including the cranial nerves, nerve roots, cervical, brachial and lumbosacral plexuses, and, rarely, the peripheral nerves. This review discusses the presentation, diagnostic evaluation, and treatment options for metastatic lesions to these components of the peripheral nervous system and is organized based on the anatomic distribution. As skull base metastases (also discussed in Chapter 14) result in cranial neuropathies, these will be covered in detail, as well as cancers that directly infiltrate the cranial nerves. Particular emphasis is placed on the clinical, imaging, and electrodiagnostic features that differentiate neoplastic plexopathies from radiation-induced plexopathies. Neurolymphomatosis, in which malignant lymphocytes invade the cranial nerves, nerve roots, brachial and lumbosacral plexuses, and peripheral nerves, is a rare manifestation of lymphoma and leukemia. Diagnoses of neurolymphomatosis are often missed or delayed given its varied presentations, resulting in poorer outcomes. Thus this disease will also be discussed in depth.

Metastatic Brachial Plexopathy with Brain and Spinal Metastasis in a Case of Recurrent Breast Carcinoma Demonstrated on 18F-FDG PET/CT

We report a case of a 56-year-old woman diagnosed with infiltrating ductal carcinoma of the left breast, who had undergone left modified radical mastectomy followed by radiotherapy and adjuvant chemotherapy. FDG PET-CT showed metastatic brachial plexopathy with intra-spinal and extra-axial brain metastasis. Metastatic brachial plexopathy along with brain and spinal metastasis is a rare condition with very less incidence. The scan also showed left para-sternal anterior chest wall recurrence with antero-superior mediastinal metastasis. 18FDG-PET scanning is a useful tool in evaluation of patients with suspected metastatic plexopathy. It may also be useful in distinguishing between radiation-induced and metastatic plexopathy. Typical pattern of FDG uptake and dual time point imaging may increase specificity and require further evaluation.

Palliative Epineurotomy for Focal Radial Malignant Peripheral Nerve Sheath Tumor in a Dog

This case report describes the diagnosis of a peripheral nerve sheath tumor of the deep branch of the radial nerve distal to the elbow in a dog. The lesion was identified using computed tomography and ultrasonography and confirmed as sarcoma on histopathological analysis of incisional biopsies. Clinical signs dramatically improved following surgical biopsy before recurring three months later. Repeat epineurotomy of the deep branch of the radial nerve resulted in clinical improvement for a further month before signs once again returned. Epineurotomy as a palliative treatment for peripheral nerve sheath tumors has not been previously described, but may have a place in palliation of clinical signs in specific cases of peripheral nerve sheath tumors in which limb amputation is not an option.

Clinical Utility of (18)F-FDG PET/CT in brachial plexopathy secondary to metastatic breast cancer

Role of fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in breast cancer is rapidly evolving. Brachial plexopathy is a rare clinical entity in follow-up of operated breast cancer patients, who presents with disease recurrence in the axilla. Conventionally, magnetic resonance imaging is the imaging modality of choice for diagnostic evaluation in these cases and only few case reports/short studies have explored the utility of PET/CT in this clinical indication. We present here a short case series to demonstrate the utility of PET/CT as an important adjunctive imaging modality to magnetic resonance to supplement diagnosis of brachial plexopathy, differentiate radiation-induced brachial plexopathy from neoplastic plexopathy, accurately restage the disease and to monitor response to chemotherapy.

Use of botulinum toxin type A for the treatment of radiation therapy-induced myokymia and neuromyotonia in a dog

CASE DESCRIPTION A 5-year-old castrated male Maltese was evaluated for intermittent clinical signs of muscle cramping and abnormal movements of the skin of the right pelvic limb at the site where an infiltrative lipoma had twice been resected. After the second surgery, the surgical field was treated with radiation therapy (RT). The clinical signs developed approximately 14 months after completion of RT. CLINICAL FINDINGS When clinical signs were present, the right biceps femoris and semitendinosus muscles in the area that received RT were firm and had frequently visible contractions, and the skin overlying those muscles had episodic vermiform movements. Electromyography of those muscles revealed abnormal spontaneous activity with characteristics consistent with myokymic discharges and neuromyotonia. Magnetic resonance imaging of the affected leg revealed no evidence of tumor regrowth. The myokymia and neuromyotonia were considered secondary to RT. TREATMENT AND OUTCOME 4 U of Clostridium botulinum toxin type A (BoNT-A) neurotoxin complex was injected into the affected muscles at each of 6 sites twice during a 24-hour period (ie, 48 U of BoNT-A were administered). The clinical signs were completely resolved 10 days after BoNT-A treatment and were controlled by repeated BoNT-A treatment every 3 to 4 months for > 1 year. CLINICAL RELEVANCE To our knowledge, this is the first report of myokymia and neuromyotonia secondary to RT in a dog. For the dog of this report, injection of BoNT-A into the affected muscles was safe, effective, and easy to perform.

Diffusivity measurements differentiate benign from malignant lesions in patients with peripheral neuropathy or plexopathy

BACKGROUND AND PURPOSE

Peripheral nerve disorders caused by benign and malignant primary nerve sheath tumors, infiltration or compression of nerves by metastatic disease, and postradiation neuritis demonstrate overlapping features on conventional MR imaging but require vastly different therapeutic approaches. We characterize and compare diffusivities of peripheral nerve lesions in patients undergoing MR neurography for peripheral neuropathy or brachial or lumbosacral plexopathy.

MATERIALS AND METHODS

Twenty-three patients, referred for MR neurography at our institution between 2003 and 2009 for a peripheral mononeuropathy or brachial or lumbosacral plexopathy and whose examinations included DWI, received a definitive diagnosis, based on biopsy results or clinical and imaging follow-up, for a masslike or infiltrative peripheral nerve or plexus lesion suspicious for tumor. Mean ADC values were determined within each lesion and compared across 3 groups (benign lesions, malignant lesions, and postradiation changes).

RESULTS

Both ANOVA and Kruskal-Wallis tests demonstrated a statistically significant difference in ADC values across the 3 groups (P = .000023, P = .00056, respectively). Post hoc pair-wise comparisons showed that the ADC within malignant tumors differed significantly from that within benign tumors and postradiation changes. ADC within benign tumors and postradiation changes did not differ significantly from each other.

CONCLUSIONS

DWI may be highly effective for the differentiation of benign from malignant peripheral nerve masslike or infiltrative lesions.

Pelvic radiculopathies, lumbosacral plexopathies, and neuropathies in oncologic disease: a multidisciplinary approach to a diagnostic challenge

The purpose of this article is to familiarize the reader with the anatomy of the major pelvic nerves and the clinical features of associated lumbosacral plexopathies. To demonstrate this we illustrate several cases of malignant lumbosacral plexopathy on computed tomography, magnetic resonance imaging, and positron emission tomography/computed tomography. A new lumbosacral plexopathy in a patient with a prior history of abdominal or pelvic malignancy is usually of malignant etiology. Biopsies may be required to definitively differentiate tumour from posttreatment fibrosis, and in cases of inconclusive sampling or where biopsies are not possible, follow-up imaging may be necessary. In view of the complexity of clinical findings often confounded by a history of prior surgery and/or radiotherapy, a multidisciplinary approach between oncologists, neurologists, and radiologists is often required for what can be a diagnostic challenge.

Diagnosis of brachial and lumbosacral plexus lesions

To most doctors, brachial and lumbosacral plexopathies are known as difficult disorders, because of their complicated anatomy and relatively rare occurrence. Both the brachial, lumbar, and sacral plexuses are extensive PNS structures stretching from the neck to axillary region and running in the paraspinal lumbar and pelvic region, containing 100000-200000 axons with 12-15 major terminal branches supplying almost 50 muscles in each limb. The most difficult part in diagnosing a plexopathy is probably that it requires an adequate amount of clinical suspicion combined with a thorough anatomical knowledge of the PNS and a meticulous clinical examination. Once a set of symptoms is recognized as a plexopathy the patients' history and course of the disorder will often greatly limit the differential diagnosis. The most common cause of brachial plexopathy is probably neuralgic amyotrophy and the most common cause of lumbosacral plexopathy is diabetic amyotrophy. Traumatic and malignant lesions are fortunately rarer but just as devastating. This chapter provides an overview of both common and rarer brachial and lumbosacral plexus disorders, focusing on clinical examination, the use of additional investigative techniques, prognosis, and treatment.

Neurologic complications of cancer and its treatment

The central nervous system (CNS) and peripheral nervous system (PNS) are very susceptible to cancer and its treatment. The most direct involvement of the nervous system manifests in the development of primary brain and spinal cord tumors. Many cancers exhibit a propensity toward spread to the CNS, and brain metastases are common problems seen in malignancies such as lung, breast, and melanoma. Such spread may involve the brain or spine parenchyma or the subarachnoid space. In the PNS, spread is usually through direct infiltration of nerve roots, plexi, or muscle by neighboring malignancies. In some cases, cancer has sudden, devastating effects on the nervous system: epidural spinal cord compression or cord transection from pathologic fractures of vertebra involved by cancer; increased intracranial pressure from intracranial mass lesion growth and edema; and uncontrolled seizure activity as a result of intracranial tumors (status epilepticus), which are neuro-oncologic emergencies. The best known indirect or remote effects of cancer on the nervous system are the neurologic paraneoplastic syndromes. Cancer can also result in a hypercoagulable state causing cerebrovascular complications. Treatment of cancer can have neurologic complications. The commonest of these complications are radiation-induced injury to the brain, spine, and peripheral nerves and chemotherapy-induced peripheral neuropathy. The suppressant effect of cancer and its treatment on the body's immune system can result in infectious complications within the nervous system.

Neurotoxicity of radiation therapy

Direct or incidental exposure of the nervous system to therapeutic irradiation carries the risk of symptomatic neurologic injury. Central nervous system toxicity from radiation includes focal cerebral necrosis, neurocognitive deficits, and less commonly cerebrovascular disease, myelopathy, or the occurrence of a radiation-induced neoplasm. Brachial or lumbosacral plexopathy are the most common syndromes of radiation toxicity affecting the peripheral nervous system. This article focuses on the clinical features, diagnosis, and management options for patients with radiation neurotoxicity.

Management of brachial plexus region tumours and tumour-like conditions: relevant diagnostic and surgical features in a consecutive series of eighteen patients

BACKGROUND

Tumours of the brachial plexus region are rare and most publications are case reports or studies with a small series of patients. The aim of this study is to present our experience in managing these lesions.

METHODS

We review 18 patients with tumours in the brachial plexus region submitted to surgical treatment in a 6 year period, including their clinical presentation, neuro-imaging data, surgical findings and outcome.

FINDINGS

The tumours comprised a heterogeneous group of lesions, including schwannomas, neurofibromas, malignant peripheral nerve sheath tumour (MPNST), sarcomas, metastases, desmoids and an aneurysmal bone cyst. The most common presentation was an expanding lump (83.33%). Eleven tumours were benign and 7 were malignant. Neurofibromatosis was present in only 2 patients (11.11%). Gross total resection was achieved in 14 patients and sub-total resection in the others. Only 3 patients presented with new post-operative motor deficits. The incidence of complications was low (16.5 %).

CONCLUSIONS

The majority of tumours were benign and most of them could be excised with a low incidence of additional deficits. Some of the malignant tumours could be controlled by surgery plus adjuvant therapy, but this category is still associated with high morbidity and mortality rates.

Nerve transfer for elbow flexion in radiation-induced brachial plexopathy: a case report

Radiation-induced brachial plexopathy is an uncommon but devastating late complication seen in patients receiving radiation therapy to the chest wall and axilla. Treatment options are unfortunately limited. We report a case of a 59-year-old woman treated with radiation therapy for breast cancer 12 years earlier, who presented with loss of elbow flexion and marked shoulder weakness. Electromyogram and intraoperative stimulation of the musculocutaneous nerve branches were consistent with a proximal motor nerve conduction block. Microsurgical transfer of median and ulnar nerve fascicles to the biceps and brachialis branches of the musculocutaneous nerve, respectively, were performed. The patient recovered MRC grade 4/5 elbow flexion after surgery. The characteristics of this disorder and surgical treatment options are reviewed.

Magnetic resonance imaging characteristics of peripheral nerve sheath tumors of the canine brachial plexus in 18 dogs

Magnetic resonance imaging (MRI) examinations from 18 dogs with a histologically confirmed peripheral nerve sheath tumor (PNST) of the brachial plexus were assessed retrospectively. Almost half (8/18) had a diffuse thickening of the brachial plexus nerve(s), six of which extended into the vertebral canal. The other 10/18 dogs had a nodule or mass in the axilla (1.2-338 cm3). Seven of those 10 masses also had diffuse nerve sheath thickening, three of which extended into the vertebral canal. The majority of tumors were hyperintense to muscle on T2-weighted images and isointense on T1-weighted images. Eight of 18 PNSTs had only minimal to mild contrast enhancement and many (13/18) enhanced heterogeneously following gadolinium DTPA administration. Transverse plane images with a large enough field of view (FOV) to include both axillae and the vertebral canal were essential, allowing in-slice comparison to detect lesions by asymmetry of structures. Higher resolution, smaller FOV, multiplanar examination of the cervicothoracic spine was important for appreciating nerve root and foraminal involvement. Short tau inversion recovery, T2-weighted, pre and postcontrast T1-weighted pulse sequences were all useful. Contrast enhancement was critical to detecting subtle diffuse nerve sheath involvement or small isointense nodules, and for accurately identifying the full extent of disease. Some canine brachial plexus tumors can be challenging to detect, requiring a rigorous multiplanar multi-pulse sequence MRI examination.

Peripheral nervous system involvement in patients with cancer

Involvement of the peripheral nervous system (PNS) is common in patients with cancer and any part, including motor neurons, sensory ganglia, nerve roots, plexuses, cranial and peripheral nerves, and neuromuscular junctions, can be affected. Different mechanisms can initiate damage associated with cancer-related PNS disorders. These include tumour infiltration, toxicity of treatments, metabolic and nutritional perturbations, cachexia, virus infections, and paraneoplastic neurological syndromes. The type of cancer, lymphoma, or solid tumour is a further determinant of a PNS disorder. In this Review we discuss the different causes and mechanisms of disorders of the PNS in patients with cancer and we will focus on their assessment and diagnosis.

Metastases to the peripheral nervous system

Cancer metastasis can affect any part of the nervous system. When the peripheral nervous system is involved, the usual targets are cranial nerves, nerve roots and plexi. However, peripheral nerves and muscles can also be affected by compression or infiltration of neoplastic cells. This review focuses in the diagnosis and treatment of metastatic complications of cancer involving plexi, peripheral nerves and muscles.

Une forme inhabituelle de plexopathie brachiale radio-induite tardive

Radiation therapy of the neck or axillary areas for cancer may result in delayed brachial plexus palsy. Differential diagnosis between radiation and tumor brachial plexopathy is difficult. We report the case of a 38-year-old woman, treated by radiation therapy for osteosarcoma of the humeral head 22 years before, who exhibited a rapidly progressive incomplete hand palsy. EMG study revealed a conduction block at the level of the lateral cord. In this case, MRI could not distinguish between a delayed radiation injury and tumor infiltration. The diagnosis was clarified with an ultrasonographic examination. Neurolysis and epineurotomy of the median trunk in the brachial and axillary areas were performed. Histological examination confirmed radiation-induced nerve injury. The characteristics of this uncommon form are reviewed with regard to the previously reported descriptions.

Brachial plexopathies: classification, causes, and consequences

The brachial plexus, which is the most complex structure of the peripheral nervous system, supplies most of the upper extremity and shoulder. The high incidence of brachial plexopathies reflects its vulnerability to trauma and the tendency of disorders involving adjacent structures to affect it secondarily. The combination of anatomic, pathophysiologic, and neuromuscular knowledge with detailed clinical and ancillary study evaluations provides diagnostic and prognostic information that is important to clinical management. Since most brachial plexus disorders do not involve the entire brachial plexus but, rather, show a regional predilection, a regional approach to assessment of plexopathies is necessary.

MR imaging of brachial plexus

The brachial plexus is a complex anatomic component originating from ventral rami of the lower cervical nerve roots from C5 to C8 and upper thoracic spinal nerve roots from T1, providing sensory and motor innervation to the upper extremities. As it is inaccessible to palpation, clinical evaluation of the brachial plexus is very challenging and localizing lesions along its course is very difficult. The gamut of pathologic conditions involving the brachial plexus includes primary tumor, direct extension of adjacent tumor, metastasis, trauma, or an inflammatory condition. MR imaging provides superior diagnostic ability due to its ability of multiplanar imaging and greater soft tissue contrast. This article discusses MR imaging findings in a variety of pathologic conditions, with special emphasis on neoplastic process.

The brachial plexus: normal anatomy, pathology, and MR imaging

The brachial plexus is the most technically and anatomically challenging area of the peripheral nervous system for diagnostic imaging. Marked improvements in spatial and contrast resolution of plexus images have resulted from the use of phased-array technology and newer MR pulse sequence designs. This article presents case material incorporating these improvements and discusses the primary factors that continue to limit MR image quality, such as inhomogenous fat suppression, motion artifacts, and small vessels that mimic or obscure plexus components, and potential solutions and imaging alternatives. Brachial plexus anatomy and its appearance on multiplanar MR images are reviewed. The morphologic features and MR signal characteristics that have been found useful in distinguishing between normal and abnormal plexus components,and in detecting neuropathic lesions, are addressed in the context of clinical indications for plexus imaging as follows: mass involving the plexus, traumatic injury, entrapment syndrome, posttreatment evaluation, and miscellaneous conditions.

IRM du plexus brachial

Magnetic resonance imaging is the method of choice for the evaluation of brachial plexopathy. Knowledge of the anatomy and normal imaging appearance is required. High-resolution imaging technique is necessary with the use of adequate coils. Evaluation of the brachial plexus requires T1 weighted sequences in three plans, T2 weighted sequences with fat suppression and if necessary the study is completed with gadolinium injection sequences with fat suppression. A CISS sequence is used if a nerve root avulsion is suspected. The spatial resolution must be optimized with the use of adapted parameters. We illustrate a variety of pathologies that can involve the brachial plexus. The pathology includes trauma, primary (neurogenic tumors, lymphomatosis) or secondary tumors, radiation plexopathy or inflammatory polyneuropathy.

Regional pain syndromes in cancer patients

Pain is one of the cardinal presenting symptoms in cancer patients and often seems to progress in the natural history of the disease. In light of the past neglect of this problem, it is becoming crucial for clinicians and researchers in the fields of oncology, pain management, and others dealing with this patient population to have a thorough understanding of the often complex pain syndromes that are relevant to managing cancer. In this article we briefly review the important topics related to cancer pain syndromes with some emphasis on those that typically generate localized pain.

Diagnostic investigations in cancer pain

Defining the specific cause of pain in patients with cancer often has substantial therapeutic and prognostic implications. This process often requires the use of specific diagnostic investigations. Here we critically review the diagnostic investigations used in the evaluation of common pain problems in patients with cancer. Familiarity with this information facilitates the development of efficient and rational diagnostic strategies.

Cancer pain: a neurological perspective

Nerve pain in cancer is common, mainly manifested by a radiculopathy associated with vertebral metastasis, by a plexopathy caused by lymph-node involvement or, more rarely, by trigeminal involvement in cancer of the head and neck. Less frequent types of nerve pain can occur as late effects of antitumour therapy, including surgery, radiation and chemotherapy. The distinction between a nociceptive and a non-nociceptive nerve pain helps in determining the most appropriate symptomatic management.

Accuracy of axillary MR imaging in treated breast cancer for distinguishing between recurrent tumour and treatment effects: does intravenous Gd-DTPA enhancement help in cases of diagnostic dilemma?

AIM

To evaluate the sensitivity and specificity of axillary magnetic resonance imaging (MRI) in symptomatic patients, who had previously been treated for breast cancer, compared with clinical outcome after a minimum of 1 year.

METHODS

One hundred and five patients underwent axillary MRI examinations and were diagnosed as axillary tumour, metastatic tumour, treatment effect or normal.

RESULTS

At MRI, 48 patients had axillary tumour, 51 had metastatic tumour (37 had both), 27 had treatment effect and 22 were normal. At outcome (median follow-up, 484 days), 54 patients were positive for axillary tumour, 59 for metastatic disease (40 had both), 21 had treatment effect alone and 18 were clear. Magnetic resonance imaging showed 89% sensitivity, 100% specificity and 94% accuracy for recurrent axillary tumour, and 85% sensitivity, 98% specificity and 90% accuracy for metastatic tumour. Soft tissue plaques were the commonest axillary disease pattern seen (37). Small volume soft tissue plaques gave the most diagnostic difficulty. Non-dynamic enhancement with intravenous Gadopentetate dimeglumine (Gd-DTPA) in a subset of 34 patients improved sensitivity for axillary tumour from 40 to 74%, and improved diagnostic confidence in 11 patients (32%). Magnetic resonance imaging had a positive management impact leading to treatment alteration in 45 patients, 43 of whom had recurrent axillary and/or metastatic tumour.

CONCLUSIONS

Tumour plaques were the commonest pattern of recurrent axillary disease. Forty-eight percent of the patients had metastatic deposits identified by MRI. Magnetic resonance imaging had excellent specificity (100%) and good sensitivity (89%) for recurrent axillary tumour compared with outcome at 1 year, which was improved by non-dynamic administration of Gd-DTPA in 32% of the subset who received it.

MR imaging of nontraumatic brachial plexopathies: frequency and spectrum of findings

Magnetic resonance imaging is the method of choice for evaluating patients with a nontraumatic brachial plexopathy. Although there is a wide range of disease processes that may cause a brachial plexopathy, radiation fibrosis, primary and metastatic lung cancer, and metastatic breast cancer account for almost three-fourths of the causes. Radiation fibrosis, the most common cause in our series, may occur several months to years after the completion of therapy. Findings of radiation fibrosis include (a) thickening and diffuse enhancement of the brachial plexus without a focal mass and (b) soft-tissue changes with low signal intensity on both T1- and T2-weighted images. Lung cancer arising in the lung apex may invade the lower portion of the brachial plexus. Many tumors may metastasize to the brachial plexus, causing a brachial plexopathy. Breast cancer is the most likely to metastasize because major lymphatic drainage routes for the breast course through the apex of the axilla.

Magnetic resonance imaging and ultrasonography in the diagnosis of a malignant peripheral nerve sheath tumor in a dog

A 9-year-old male neutered mixed breed dog had a two-month history of progressive left thoracic limb lameness. There was electromyographic evidence of denervation potentials in all muscles of this limb. In magnetic resonance images a multilobulated, hyperintense mass was visible caudal to the middiaphysis of the left humerus on T-2 weighted images. The mass, which was isointense with surrounding tissue on T1 weighted images, extended proximally towards the brachial plexus. The mass was also visible as a fusiform structure of mixed echogenicity sonographically, although fine-needle aspiration performed at this time was nondiagnostic. A malignant peripheral nerve sheath tumor was diagnosed histopathologically.

MRI appearances of the axilla in treated breast cancer

Differentiation between recurrent axillary disease and changes due to radiotherapy or surgery has major implications for management in patients following breast cancer treatment, but clinical examination of the axilla may be difficult. This study was undertaken to correlate the MRI appearances of the axilla following breast cancer treatment with clinical outcome. 74 women with treated breast cancer were evaluated by MRI (0.5 T) and the appearances defined by consensus. Outcome was assessed by long-term clinical follow-up. 62 women had symptoms related to the axilla while 12 were scanned to stage the axilla. None of the axillary staging group had abnormal MRI appearances and none of these subsequently developed recurrence. The 62 symptomatic women were subdivided according to MRI appearances. 22 had normal axillary appearances, 18 had an axillary mass and 22 women had abnormal axillary appearances (rated mild, moderate and severe) in the absence of a mass. Normal axillary appearances on MRI excluded recurrent disease as the cause of symptoms with a specificity of 94.7% and a positive predictive value (PPV) of 95.5%. The presence of an axillary mass was commonly but not exclusively due to recurrent disease (sensitivity 68.4%, specificity 88.4%, PPV 72.2%). Sensitivity for diagnosis of axillary recurrence was increased to 89.5% with a specificity of 76.7% if the criteria for recurrent disease were taken as either the presence of an axillary mass or severe axillary changes in the absence of a mass lesion.

Use of positron emission tomography in evaluation of brachial plexopathy in breast cancer patients

18-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has previously been used successfully to image primary and metastatic breast cancer. In this pilot study, 19 breast cancer patients with symptoms/signs referrable to the brachial plexus were evaluated with 18FDG-PET. In 11 cases computerized tomography (CT) scanning was also performed. Of the 19 patients referred for PET study, 14 had abnormal uptake of 18FDG in the region of the symptomatic plexus. Four patients had normal PET studies and one had increased FDG uptake in the chest wall that accounted for her axillary pain. CT scans were performed in 9 of the 14 patients who had positive brachial plexus PET studies; six of these were either normal or showed no clear evidence of recurrent disease, while three CTs demonstrated clear brachial plexus involvement. Of two of the four patients with normal PET studies, one has had complete resolution of symptoms untreated while the other was found to have cervical disc herniation on magnetic resonance imaging (MRI) scan. The remaining two patients almost certainly had radiation-induced plexopathy and had normal CT, MRI and PET study. These data suggest that 18FDG-PET scanning is a useful tool in evaluation of patients with suspected metastatic plexopathy, particularly if other imaging studies are normal. It may also be useful in distinguishing between radiation-induced and metastatic plexopathy.

Magnetic resonance imaging in cancer-related lumbosacral plexopathy

OBJECTIVE

To study the relative utility of computed tomography (CT) and magnetic resonance imaging (MRI) of the lumbosacral plexus in patients with systemic cancer and plexopathy.

DESIGN

In a retrospective study, we identified all patients encountered at Mayo Clinic Rochester between 1987 and 1993 with a diagnosis of lumbosacral plexopathy, and we selected for analysis those with MRI scans of the plexus (an abnormal finding was not necessary for inclusion) and a clinical and electrophysiologic appearance consistent with a diagnosis of metastatic lumbosacral plexopathy.

MATERIAL AND METHODS

The study group consisted of 31 patients (20 men and 11 women). The types of tumor were as follows: prostatic, 10 patients; colorectal, 7; bladder, 3; cervical, 3; and other, 8. Eighteen patients had received pelvic radiotherapy before diagnosis of lumbosacral plexopathy. All available MRI scans (in 27 patients) were reviewed blinded; the initial imaging report was used if the actual scans were unavailable (in 4). CT had been done in 22 patients, and results for 16 were available for blinded review. Original reports were available for the other six.

RESULTS

Direct involvement of the lumbosacral plexus by tumor was evident on 23 MRI studies, and 6 others showed widespread metastatic disease in the region of the plexus. On 13 CT examinations, direct involvement of the lumbosacral plexus by tumor was noted. In four patients, MRI findings were abnormal and CT findings were normal. No patient had abnormal CT findings and normal MRI findings.

CONCLUSION

In this retrospective review, MRI was more sensitive than CT for diagnosing cancer-induced lumbosacral plexopathy. Thus, use of MRI should be considered in the diagnostic work-up of patients with clinical and electrophysiologic evidence of plexopathy and suspected systemic cancer.

Radiation-induced malignant fibrous histiocytoma of the brachial plexus

Brachial plexopathy is a common and disabling complication in cancer patients most often attributed to metastasis or radiation-induced fibrosis. Occasionally, other rare but potentially treatable causes are found. A 73 year old woman had a left radical mastectomy followed by radiation to the chest wall and axilla 24 years ago. She recently presented with left arm pain, chronic, nonprogressive lymphedema, profound distal arm sensory loss and progressive severe hand weakness. There was moderate atrophy of all intrinsic hand muscles, anesthesia of the hypothenar eminence and 4th and 5th digits, and no adenopathy or palpable mass in the axilla. EMG confirmed a brachial plexopathy. MRI showed loss of tissue planes consistent with radiation fibrosis, but CT showed a discrete mass in the brachial plexus. Open biopsy showed pleomorphic spindle shaped cells with immunoperoxidase stains consistent with malignant fibrous histiocytoma. Radiation-induced malignant fibrous histiocytoma may present with a brachial plexopathy in the absence of a palpable mass and should be considered in the differential diagnosis of brachial plexus lesions in cancer patients. CT scanning through the plexus may be useful when MRI is normal or equivocal.