The posterior oblique ligament in MRI of acute knee trauma

OBJECTIVE

To identify the posterior oblique ligament and assess incidence and patterns of injury to the ligament on MRI of acute knee trauma.

SUBJECTS AND METHODS

One hundred twenty-three MRI studies met the study criteria. For each case, the posterior oblique ligament was identified and scored as injured or normal. Incidence of proximal and distal posterior oblique ligament tears was calculated. Fisher's tests were employed to determine significance of association between tears of the posterior oblique ligament and components of the posteromedial corner and other capsuloligamentous structures of the knee.

RESULTS

The posterior oblique ligament was reliably identified as a distinct structure in 123 MRI scans that met the criteria and was consistently labeled as intact or torn. Posterior oblique ligament tear was seen in 61.7% of knee trauma with proximal injury in 56.5% and distal injury in 97.3% of positive cases. Posterior oblique ligament disruption was a part of multiligamentous injury in 94.7% of positive cases. Posterior oblique ligament injuries (n = 76) had an extremely significant relationship with oblique popliteal ligament tears (n = 27) (p = 0.0001), semimembranosus tendon insertion tears (n = 15) (p = 0.0005), and medial collateral ligament tears (n = 15) (p = 0.0005) and a highly significant association with medial meniscus tears (n = 68) (p = 0.0049) and posterior cruciate ligament tears (n = 12) (p = 0.0033). The association with anterior cruciate ligament tears (n = 53) was not significant.

CONCLUSIONS

The posterior oblique ligament is a distinct radiological entity consistently identified in acute trauma MRI. Disruptions of the distal posterior oblique ligament are frequent in complex knee injury, notably in association with oblique popliteal ligament, medial collateral ligament, and semimembranosus tendon tears.

Acute Lead Encephalopathy Secondary to Ayurvedic Medication Use: Two Cases with Review of Literature

Ayurvedic medicine is an ancient and traditional system of health care. It is safe but inadvert and unsupervised use can lead to serious health complications. Lead is a common constituent of these medicines. Here authors describe two cases of lead encephalopathy as a result of long-term ayurvedic medication intake. First case was a 54-year-old female taking ayurvedic medications since long time presented with acute confusional state and memory disturbances with abdominal pain. MRI brain showed symmetric basal ganglia and cortical signal changes and edema with significantly elevated lead levels in blood. She responded to chelation therapy with oral penicillamine with complete clinical and radiological resolution. Second case presented was a 45-year female taking ayurvedic medications for hypertension presented with headaches and rapid deterioration in sensorium leading to coma and death. MRI brain showed diffuse cerebral edema with basal ganglia signal changes with elevated lead levels in blood. These two cases highlight the need for increased awareness that some Ayurvedic medicines may contain potentially harmful levels of lead and people who use them are at risk of developing associated toxicity which can even be fatal.

Magnetic resonance imaging of ankle ligaments: A pictorial essay

Ankle trauma is commonly encountered and is most often a sprain injury affecting the ligaments. Accurate diagnosis and appropriate treatment rest on knowledge of complex ligamentous anatomy of ankle and the entire spectrum of pathologies. Magnetic resonance imaging (MRI) is the imaging modality of choice for diagnosing ligament pathologies because of its multiplanar capability and high soft tissue contrast. With MRI, it is possible to triage and attribute the cause of post traumatic ankle pain to bone, ligament, or tendon pathologies, which otherwise overlap clinically. In this pictorial essay, emphasis is given to the intricate and unique anatomy and orientation of ankle ligaments. Pathologies of ankle ligaments have been elaborated.

MRI of lateral hindfoot impingement

Lateral hindfoot impingement (LHI) is a subtype of ankle impingement syndrome with classic MRI findings. Biomechanically, LHI is the sequela of lateral transfer of weight bearing from the central talar dome to the lateral talus and fibula. The transfer occurs due to collapse of the medial arch of the foot, most commonly from posterior tibial tendon (PTT) and spring ligament (SL) insufficiency. Clinical features include lateral hindfoot pain, deformity, and overpronation on gait analysis. MRI changes continuously reflect the altered biomechanics as the syndrome progresses over time, including typical and often sequential changes of PTT and SL failure, increasing heel valgus, talocalcaneal and subfibular impingement, and finally lateral soft tissue entrapment. In addition to diagnosis, MRI is a useful adjunct to plan surgical treatment.

Neuroschistosomiasis: An Unusual Intracranial Space Occupying Lesion

BACKGROUND

Neuroschistosomiasis is an uncommonly reported disease.

CASE CHARACTERISTICS

An adolescent Indian boy residing in Kenya presented with headache, visual symptoms and seizures, with MRI showing space-occupying lesions in the occipital lobe and cerebellum.

OBSERVATION

Brain biopsy was diagnostic of neuro-schistosomiasis; complete recovery was seen with praziquantel and corticosteroid therapy.

MESSAGE

This case highlights the importance of considering epidemiology in differential diagnosis and establishing definitive diagnosis even if it is by invasive methods.

Pure Medial Elbow Dislocation without Concomitant Fracture in a 10-Year-Old Child

Pediatric elbow dislocations are rare injuries and are often accompanied by concomitant fractures. We report a rare case of medial dislocation of the right elbow without accompanying fracture in a 10.5-year-old boy after fall from a bicycle. After radiographic and magnetic resonance imaging evaluation, closed reduction under general anesthesia was performed and the elbow was immobilized in a posterior above-elbow slab. Elbow mobilization was started after 2 weeks and the posterior slab was discontinued after 4 weeks. At 3 months, the patient had a full range of active elbow flexion extension and pronation supination. At 4-year followup, radiographs show a normal alignment of the elbow with mild changes of heterotopic ossification. We believe that this is the first such case ever reported in literature. Early recognition and prompt diagnosis is the key to achieve a good result.

Stroke mimic: Perfusion magnetic resonance imaging of a patient with ictal paralysis

We present an uncommon case of clinically diagnosed window period stroke subsequently recognised on diffusion - perfusion MRI as ictal paralysis due to focal inhibitory seizures or negative motor seizures. This case highlights the importance of MRI with perfusion imaging in establishing the diagnosis of stroke mimics and avoiding unnecessary thrombolysis.

Post-treatment imaging of high-grade gliomas

Current standard of care for treatment of newly diagnosed high grade gliomas is surgery followed by concomitant radiotherapy (RT) and chemotherapy (CT) with temozolomide (TMZ). Recently, bevacizumab, an anti – angiogenic agent has also been approved for treatment of recurrent gliomas. Baseline imaging after excision is optimally obtained in the first 24 hours. When baseline postoperative imaging is delayed beyond 24 hours, subacute hemorrhage, subacute ischemia and inflammation at the resection margins render differentiation from residual tumor challenging. Radiation necrosis is a well recognized entity and is differentiated from recurrence based on morphology on structural imaging, presence of lipid – lactate complexes with lack of choline on spectroscopy and low normalized cerebral blood volume (CBV) ratios at perfusion imaging. Novel chemotherapies have lead to the occurrence of interesting but sometimes confusing post treatment imaging appearances including the phenomena of ‘pseudoprogression’ and ‘pseudoresponse’. Pseudoprogression refers to transient, self resolving focal enhancement mediated by TMZ-induced increased vascular permeability and local inflammatory response. Pathologically, these lesions do not have viable tumor. The lesions stabilize or regress without further treatment and are usually clinically asymptomatic. Pseudoresponse refers to rapid regression of enhancement, perfusion, mass effect and midline shift caused by the anti – angiogenic effect of bevacizumab. It is termed pseudoresponse since biological tumor persists as non-enhancing altered signal. It is important for radiologists to be aware of these entities seen on post treatment imaging of gliomas, as misinterpretation may lead to inappropriate management decisions and prognostication.

Imaging of cartilage repair procedures

The rationale for cartilage repair is to prevent precocious osteoarthritis in untreated focal cartilage injuries in the young and middle-aged population. The gamut of surgical techniques, normal postoperative radiological appearances, and possible complications have been described. An objective method of recording the quality of repair tissue is with the magnetic resonance observation of cartilage repair tissue (MOCART) score. This scoring system evaluates nine parameters that include the extent of defect filling, border zone integration, signal intensity, quality of structure and surface, subchondral bone, subchondral lamina, and records presence or absence of synovitis and adhesions. The five common techniques of cartilage repair currently offered include bone marrow stimulation (microfracture or drilling), mosaicplasty, synthetic resorbable scaffold grafts, osteochondral allograft transplants, and autologous chondrocyte implantation (ACI). Complications of cartilage repair procedures that may be demonstrated on magnetic resonance imaging (MRI) include plug loosening, graft protuberance, graft depression, and collapse in mosaicplasty, graft hypertrophy in ACI, and immune response leading to graft rejection, which is more common with synthetic grafts and cadaveric allografts.

Stand alone mechanical thrombectomy (with penumbra system) for acute ischemic stroke based on MR imaging: Single center experience

BACKGROUND

There is dismal rate of recanalization following intravenous thrombolysis of large vessel occlusive ischemic stroke. Trials on use of mechanical clot retrievers in acute ischemic stroke have used time from onset and clinical deficit at presentation as the main indications for intervention.

MATERIALS AND METHODS

Retrospective analysis of case records of acute stroke seen between May 2009 and October 2011 was done. It revealed 23 patients with acute ischemic stroke treated by mechanical thrombectomy using Penumbra system (PS). We used magnetic resonance (MR) imaging in correlation with clinical presentation to determine patients likely to benefit from recanalization and accordingly offered or at times deferred revascularization. A comparison of approach and outcomes was done with other relevant trials/reports.

RESULTS

Recanalization was achieved in all but one patient. Median modified Rankin Scale (mRS) score at 90 days was 2. Good clinical outcome (mRS ≤ 2) was achieved in 56.5% compared with 25% in Penumbra pivotal trial and 36% in multi Mechanical Embolus Removal in Cerebral Ischemia (multi MERCI) trial. All cause mortality was 13.04%. Symptomatic intracerebral hemorrhage (ICH) occurred in two patients (8.6%).

CONCLUSION

Analysis of our results suggests that PS is safe and effective (91.3%) in recanalizing cerebral vessels without concomitant thrombolytics.

Case Series: Cyclops lesion - extension loss after ACL reconstruction

Localized anterior arthrofibrosis (cyclops lesion) is the second most common cause of extension loss after anterior cruciate ligament (ACL) reconstruction. We present and discuss two patients with prior ACL reconstructions, who presented with pain and loss of extension following surgery. MRI and arthroscopy of the knee revealed typical features of a cyclops lesion. The patients showed significant symptomatic improvement following arthroscopic resection of these lesions.

Dorsal spinal epidural cavernous hemangioma

A 61-year-old female patient presented with diffuse pain in the dorsal region of the back of 3 months duration. The magnetic resonance imaging showed an extramedullary, extradural space occupative lesion on the right side of the spinal canal from D5 to D7 vertebral levels. The mass was well marginated and there was no bone involvement. Compression of the adjacent thecal sac was observed, with displacement to the left side. Radiological differential diagnosis included nerve sheath tumor and meningioma. The patient underwent D6 hemilaminectomy under general anesthesia. Intraoperatively, the tumor was purely extradural in location with mild extension into the right foramina. No attachment to the nerves or dura was found. Total excision of the extradural compressing mass was possible as there were preserved planes all around. Histopathology revealed cavernous hemangioma. As illustrated in our case, purely epidural hemangiomas, although uncommon, ought to be considered in the differential diagnosis of spinal epidural soft tissue masses. Findings that may help to differentiate this lesion from the ubiquitous disk prolapse, more common meningiomas and nerve sheath tumors are its ovoid shape, uniform T2 hyperintense signal and lack of anatomic connection with the neighboring intervertebral disk or the exiting nerve root. Entirely extradural lesions with no bone involvement are rare and represent about 12% of all intraspinal hemangiomas.

Magnetic resonance imaging in cerebral malaria: a report of four cases

OBJECTIVES

This is a retrospective institutional review of clinical data and radiological findings of cerebral malaria patients presenting to a tertiary centre in India, which is an known to be endemic for malarial disease.

METHODS

The present series describes MRI in four cases all of which revealed bithalamic infarctions with or without haemorrhages in patients with cerebral malaria, and this review examines a subset of patients with this condition. In addition, acute haemorrhagic infarctions were also seen the in brain stem, cerebellum, cerebral white matter and insular cortex in two of the four patients.

RESULTS

In this series, the patient with cerebellum and brain stem involvement died. The remaining three survived with antimalarial and supportive treatment. No neurological symptoms were noted on clinical follow-up. MRI follow-up was obtained in only one of the three patients (3 months post-treatment) and showed resolution of thalamic infarctions.

CONCLUSION

These imaging features may help in the early diagnosis of cerebral malaria so that early treatment can begin and improve the clinical outcome.

Bone metastasis of glandular cardiac myxoma mimicking a metastatic carcinoma

Skeletal metastasis from a cardiac myxoma is rare. We describe an extremely unusual case of a cardiac myxoma metastasing to the femur in a 46-year-old female presenting with pain in the right hip. Radiographs showed an expansile lytic lesion with pathological fracture involving the neck and proximal shaft of the right femur. Histology revealed features of cardiac myxoma with heterologous glandular elements, which was initially mistaken for a metastatic mucin-secreting adenocarcinoma.

Giant-cell tumour of the synovium in a facet joint in the thoracic spine of a child

Giant-cell tumour of the synovium is known to affect the fingers or toes of adults. It has seldom been described in the spine and rarely in the thoracic vertebrae or in a child. The lesions of giant-cell tumour of the synovium have a classical radiological appearance, but require a high index of suspicion for correct recognition. Unlike giant-cell tumour of the synovium at other well-known sites, spinal lesions lack the characteristic papillary architecture, thereby raising other diagnostic possibilities. We describe a giant-cell tumour of the synovium of the left facet joint of a thoracic vertebra in a nine-year-old girl. The tumour was treated successfully by surgical excision.

Pituitary tuberculosis

Tuberculous involvement of pituitary is extremely rare and is usually not suspected while dealing with pituitary adenomas, even in patients with history of systemic tuberculosis. We report a case of pituitary tuberculoma in a patient who was undergoing treatment for prostatic tuberculosis. Although diagnosis of sellar tuberculomas is difficult on clinical and radiological examinations, pituitary tuberculomas should be considered in the differential diagnosis of suprasellar masses, especially in developing countries as the condition is potentially curable with antituberculous treatment.