A cervical spine model to predict injury scenarios and clinical instability.

Sports Biomech. 2009 Mar; 8(1): 78-95Tchako A, Sadegh AA complete and detailed three-dimensional finite element model of the human cervical spine (C1-C7), including soft and hard tissues, was created using a digitized geometric measurement tool. The model was validated against existing experimental studies in flexion, extension, lateral bending, and axial rotation. The aims of this study were to use the model to simulate the mechanisms of injury scenarios, such as diving and football accidents, and to correlate the external and internal responses of the spinal components to disc herniation and clinical instability. It was determined that a shear-generated flexion moment of about 10 Nm or a compression-flexion load of 450 N would generate significant stresses and strains in the discs, together with sufficient posterior-anterior displacement and rotational angulation of the vertebrae, to place the mid and lower cervical spine at risk of clinical instability or disc herniation. The results revealed that the location of the maximum stresses in the discs could not be directly correlated with the type of loads. In addition, for the loadings considered, the maximum displacement of the spine could be reduced by as much as 50% when the restraint of the cervical spine is changed from a C7-T1 to C7-T1 and C1-C2 fixed conditions.

Occult dural arteriovenous fistula causing rapidly progressive conus medullaris syndrome and paraplegia after lumbar microdiscectomy.

Spine J. 2009 May 11; Stevens EA, Powers AK, Morris PP, Wilson JABACKGROUND CONTEXT: A spinal dural arteriovenous fistula (DAVF) is a known cause of venous congestive myelopathy. These lesions are thought to be acquired. There exist two prior reports that describe DAVF presenting with slowly progressive myelopathy years after lumbar disc surgery. PURPOSE: We report the first case of a preexistent, asymptomatic DAVF that became acutely symptomatic after lumbar microdiscectomy causing rapidly progressive conus medullaris syndrome and paraplegia. STUDY DESIGN: Case report. METHODS: A 53-year-old Caucasian male presented with urinary retention, fecal incontinence, and progressive loss of function in bilateral lower extremities less than 3 months after a lumbar discectomy at an outside facility. The patient underwent microdiscectomy at L4/L5 and L5/S1 for left-sided radicular symptoms and evidence of herniated discs on magnetic resonance imaging (MRI). The patient's preoperative pain improved after the discectomy, but his bowel, bladder, and lower extremity function deteriorated steadily after discharge. Postoperative MRI showed salient serpentine vessels in the region of L1 and L2 with an enlarged T2 bright conus medullaris. Retrospective review of preoperative MRI revealed the presence of similar but less pronounced findings. A spinal arteriogram confirmed concerns of an arteriovenous malformation. The patient was transferred to our facility for definitive management of his DAVF via catheter embolization. RESULTS: Complete fistula obliteration was confirmed at the time of embolization and at 8 weeks follow-up with selective spinal angiography. The appearance of the conus medullaris normalized on follow-up MRI. The patient made a slow but significant recovery in rehabilitation. He regained the ability to independently ambulate but remains significantly disabled secondary to residual lower extremity weakness and spasticity. He continues self-catheterization for persistent neurogenic bladder dysfunction. CONCLUSIONS: This represents the first case of an occult spinal DAVF becoming acutely symptomatic after lumbar disc surgery. Although the etiology of the lesion and its symptomatic progression remains unknown, an alteration of blood flow through the DAVF as a result of surgery may have resulted in progressive venous congestive myelopathy. The present case highlights the importance of considering a spinal DAVF in the differential diagnosis of any patient with signs of myelopathy or conus medullaris syndrome after lumbar discectomy. In addition, this case underscores the gravity of recognizing subtle features that suggest the presence of an occult vascular malformation on preoperative imaging, as symptomatic progression of these lesions carries significant potential morbidity.

Oncocytic Carcinoma Arising in the Submandibular Gland with Disseminated Bone Metastases.

South Med J. 2009 May 7; Lee JS, Choi JH, Oh YHOncocytic carcinoma of the head and neck is a very rare neoplasm. It usually occurs in the parotid glands. Only 11 cases of oncocytic carcinoma of the submandibular gland have been reported, and no cases have shown distant bone metastasis. A 67-year-old man presented with a tingling sensation in both hands due to a herniated cervical disc. A whole body bone scan and PET-CT showed disseminated bone metastases. Neck CT revealed a 1.7 cm calcified left submandibular mass. The submandibular gland and bone marrow biopsies were consistent with oncocytic carcinoma. Our case is the first report of oncocytic carcinoma of the submandibular gland with disseminated bone metastases.

[Ambulatory diskectomy. Safe and appreciated alternative for selected patients]

Lakartidningen. 2009 Mar 4-10; 106(10): 679-80Skeppholm M, Frost A, Olerud C