Patrick H. Luetmer

Systematic Literature Review of Imaging Features of Spinal Degeneration in Asymptomatic Populations

This meta-analysis of the literature reveals that imaging findings of spine degeneration are present in high proportions of asymptomatic individuals, increasing with age. Many imaging-based degenerative features are likely part of normal aging and unassociated with pain. BACKGROUND AND PURPOSE: Degenerative changes are commonly found in spine imaging but often occur in pain-free individuals as well as those with back pain. We sought to estimate the prevalence, by age, of common degenerative spine conditions by performing a systematic review studying the prevalence of spine degeneration on imaging in asymptomatic individuals. MATERIALS AND METHODS: We performed a systematic review of articles reporting the prevalence of imaging findings (CT or MR imaging) in asymptomatic individuals from published English literature through April 2014. Two reviewers evaluated each manuscript. We selected age groupings by decade (20, 30, 40, 50, 60, 70, 80 years), determining age-specific prevalence estimates. For each imaging finding, we fit a generalized linear mixed-effects model for the age-specific prevalence estimate clustering in the study, adjusting for the midpoint of the reported age interval. RESULTS: Thirty-three articles reporting imaging findings for 3110 asymptomatic individuals met our study inclusion criteria. The prevalence of disk degeneration in asymptomatic individuals increased from 37% of 20-year-old individuals to 96% of 80-year-old individuals. Disk bulge prevalence increased from 30% of those 20 years of age to 84% of those 80 years of age. Disk protrusion prevalence increased from 29% of those 20 years of age to 43% of those 80 years of age. The prevalence of annular fissure increased from 19% of those 20 years of age to 29% of those 80 years of age. CONCLUSIONS: Imaging findings of spine degeneration are present in high proportions of asymptomatic individuals, increasing with age. Many imaging-based degenerative features are likely part of normal aging and unassociated with pain. These imaging findings must be interpreted in the context of the patients clinical condition.

Measurement of cerebrospinal fluid flow at the cerebral aqueduct by use of phase-contrast magnetic resonance imaging: technique validation and utility in diagnosing idiopathic normal pressure hydrocephalus.

OBJECTIVE We analyzed the reliability of a protocol for measuring quantitative cerebrospinal fluid (CSF) flow at the cerebral aqueduct and established the range of CSF flows in normal elderly patients, patients with Alzheimer’s and other forms of dementia, and patients with idiopathic normal pressure hydrocephalus (NPH). METHODS A constant flow phantom was used to establish the accuracy of the CSF flow measurement. The clinical variability of the measurement was estimated by calculating the standard deviations and coefficients of variation of intra- and interobserver and intertrial data sets derived from three normal volunteers. A total of 236 patients were studied, including 47 normal elderly patients, 115 patients with cognitive impairment (9 with mild cognitive impairment, 46 with Alzheimer’s disease, and 60 with other cognitive impairment), 31 patients in whom NPH was suspected but ultimately excluded, and 43 patients with a final clinical diagnosis of NPH. RESULTS The intraobserver, interobserver, and intertrial measurement variations of 6.4, 5.4, and 8.8%, respectively, were substantially smaller than the wide variation observed among subjects. There was no statistically significant difference in flow between normal elderly patients and patients with cognitive impairment (P = 0.91). When these populations were pooled, the average flow was 8.47 ml/min (standard deviation, 4.23; range, 0.9–18.5 ml/min). The average flow rate in patients with a final clinical diagnosis of NPH was 27.4 ml/min (standard deviation, 15.3; range, 3.13–62.2 ml/min). This was significantly higher than the flow rate in each of the other three groups (all, P < 0.001). CONCLUSION CSF flow measurements of less than 18 ml/min with a sinusoidal flow pattern are normal. CSF flow of greater than 18 ml/min suggests idiopathic NPH.

Use of Cerebrospinal Fluid Flow Rates Measured by Phase-Contrast MR to Predict Outcome of Ventriculoperitoneal Shunting for Idiopathic Normal-Pressure Hydrocephalus

OBJECTIVE To determine whether favorable clinical response and magnitude of improvement are associated with increased aqueductal cerebrospinal fluid (CSF) flow rates in patients who undergo ventriculoperitoneal shunting (VPS) for idiopathic normal-pressure hydrocephalus (NPH). PATIENTS AND METHODS Between January 1995 and June 2000, 49 patients (14 men and 35 women; mean age, 72.9 years; range, 54-88 years) underwent magnetic resonance quantification of aqueductal CSF flow followed by VPS for presumed idiopathic NPH at the Mayo Clinic, Rochester, Minn. Logistic regression models for the odds of any improvement in score as a function of aqueductal CSF flow and separate models for any improvement in gait, incontinence, cognition, and total score were constructed. RESULTS Forty-two patients (86%) had improvement in gait at postoperative follow-up (mean, 10 months). Of the 32 patients with incontinence, 27 (69%) improved. Of the 36 patients with cognitive impairment, 16 (44%) improved. In univariate and fully adjusted models, increased CSF flow through the aqueduct was not significantly associated with improvement or the magnitude of improvement in gait, cognition, or incontinence. Thirty-six patients underwent high-volume lumbar puncture preoperatively, of whom 5 (14%) had no response. The aqueductal CSF flow rates of these 5 patients were significantly higher than those of the patients who improved after lumbar puncture. Postoperative complications occurred in 15 patients. The aqueductal CSF flow rates in these 15 patients were not significantly different from those of patients who experienced no complications. CONCLUSION Among patients who underwent VPS for the treatment of NPH, measurement of CSF flow through the cerebral aqueduct did not reliably predict which patients would improve after shunting or the magnitude of improvement.

Right Aortic Arch With Isolation of the Left Subclavian Artery: Case Report and Review of the Literature

Of the right aortic arch anomalies, a right arch with isolation of the left subclavian artery is the least common. Herein we describe a 52-year-old woman in whom this anomaly was discovered during cerebral angiography for evaluation of a giant symptomatic intracavernous carotid aneurysm. Isolation of the left subclavian artery may be suggested in a patient with a right arch in whom the blood pressure or pulse in the left upper extremity is diminished. Although the isolated left subclavian artery produces the hemodynamic alterations of a subclavian steal, review of the 39 cases reported in the literature revealed only 5 patients with symptoms suggestive of vertebrobasilar insufficiency and 5 patients with weakness of the left upper extremity. Although the patient we describe had no known heart disease, congenital heart disease was present in 23 of the 39 reported cases (59%), tetralogy of Fallot occurring most frequently.

The role of MR myelography with intrathecal gadolinium in localization of spinal CSF leaks in patients with spontaneous intracranial hypotension.

BACKGROUND AND PURPOSE: Localization of spinal CSF leaks in CSF hypovolemia is critical in directing focal therapy. In this retrospective review, our aim was to determine whether GdM was helpful in confirming and localizing spinal CSF leaks in patients in whom no leak was identified on a prior CTM. MATERIALS AND METHODS: Forty-one symptomatic patients with clinical suspicion of SIH were referred for GdM after undergoing at least 1 CTM between February 2002 and August 2010. A retrospective review of the imaging and electronic medical records was performed on each patient. RESULTS: In 17 of the 41 patients (41%), GdM was performed for follow-up of a previously documented leak at CTM. In the remaining 24 patients (59%), in whom GdM was performed for a suspected CSF leak, which was not identified on CTM, GdM localized the CSF leak in 5 of 24 patients (21%). In 1 of these 5 patients, GdM detected the site of leak despite negative findings on brain MR imaging, spine MR imaging, and CTM of the entire spine. Sixteen of 17 patients with previously identified leaks underwent interval treatment, and leaks were again identified in 12 of 17 (71%). CONCLUSIONS: GdM is a useful technique in the highly select group of patients who have debilitating symptoms of SIH, a high clinical index of suspicion of spinal CSF leak, and no demonstrated leak on conventional CTM. Intrathecal injection of gadolinium contrast remains an off-label use and should be reserved for those patients who fail conventional CTM.

MRI Findings of Disc Degeneration are More Prevalent in Adults with Low Back Pain than in Asymptomatic Controls: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE: Imaging features of spine degeneration are common in symptomatic and asymptomatic individuals. We compared the prevalence of MR imaging features of lumbar spine degeneration in adults 50 years of age and younger with and without self-reported low back pain. MATERIALS AND METHODS: We performed a meta-analysis of studies reporting the prevalence of degenerative lumbar spine MR imaging findings in asymptomatic and symptomatic adults 50 years of age or younger. Symptomatic individuals had axial low back pain with or without radicular symptoms. Two reviewers evaluated each article for the following outcomes: disc bulge, disc degeneration, disc extrusion, disc protrusion, annular fissures, Modic 1 changes, any Modic changes, central canal stenosis, spondylolisthesis, and spondylolysis. The meta-analysis was performed by using a random-effects model. RESULTS: An initial search yielded 280 unique studies. Fourteen (5.0%) met the inclusion criteria (3097 individuals; 1193, 38.6%, asymptomatic; 1904, 61.4%, symptomatic). Imaging findings with a higher prevalence in symptomatic individuals 50 years of age or younger included disc bulge (OR, 7.54; 95% CI, 1.28–44.56; P = .03), spondylolysis (OR, 5.06; 95% CI, 1.65–15.53; P < .01), disc extrusion (OR, 4.38; 95% CI, 1.98–9.68; P < .01), Modic 1 changes (OR, 4.01; 95% CI, 1.10–14.55; P = .04), disc protrusion (OR, 2.65; 95% CI, 1.52–4.62; P < .01), and disc degeneration (OR, 2.24; 95% CI, 1.21–4.15, P = .01). Imaging findings not associated with low back pain included any Modic change (OR, 1.62; 95% CI, 0.48–5.41, P = .43), central canal stenosis (OR, 20.58; 95% CI, 0.05–798.77; P = .32), high-intensity zone (OR = 2.10; 95% CI, 0.73–6.02; P = .17), annular fissures (OR = 1.79; 95% CI, 0.97–3.31; P = .06), and spondylolisthesis (OR = 1.59; 95% CI, 0.78–3.24; P = .20). CONCLUSIONS: Meta-analysis demonstrates that MR imaging evidence of disc bulge, degeneration, extrusion, protrusion, Modic 1 changes, and spondylolysis are more prevalent in adults 50 years of age or younger with back pain compared with asymptomatic individuals.

When Should I Do Dynamic CT Myelography? Predicting Fast Spinal CSF Leaks in Patients with Spontaneous Intracranial Hypotension

Which patients with intracranial hypotension will need dynamic CT myelography? The authors assessed brain and spine MRI studies and opening pressure measurements in 150 consecutive patients with intracranial hypotension to see if these can predict fast CSF spine leaks that will require dynamic myelography. Fast leaks were present in 21% and correlated well with the presence of spinal extra-arachnoid fluid. No correlation between fast leaks and brain MRI findings was found. Thus, when spinal extra-arachnoid fluid is documented on MRI studies there is no need for conventional CT myelography but the patient should be directly studied with dynamic CT myelography. BACKGROUND AND PURPOSE: Some patients with SIH have fast CSF leaks requiring dynamic CTM for localization; however, patients generally undergo conventional CTM before a dynamic study. Our aim was to determine whether findings on head MR imaging, spine MR imaging, or opening pressure measurements can predict fast spinal CSF leaks. MATERIALS AND METHODS: A retrospective review was performed on 151 consecutive patients referred for CTM to evaluate for spinal CSF leak. Head MR imaging was evaluated for diffuse dural enhancement and “brain sag,” and spine MR imaging for presence of an extradural fluid collection. The opening pressure was recorded. The CTM was scored as no leak, slow leak localized on conventional CTM, or fast leak that required dynamic CTM. RESULTS: Fast CSF leaks were identified in 32 (21%), slow leaks in 36 (24%), and no leak in 83 (55%) of 151 patients on initial CTM. There was significant association between spinal extra-arachnoid fluid on MR imaging and the presence of a fast leak (sensitivity 85%, specificity 79%, P < .0001). There was not significant association between fast leak and findings on head MR imaging (P = .27) or opening pressure (P = .30). CONCLUSIONS: If all patients with spinal extra-arachnoid CSF on MR imaging had been sent directly to dynamic CTM, repeat myelography would have been avoided in most patients with fast leaks (23 of 27; 85%). However, a minority of patients with slow or no leaks would have been converted from conventional to dynamic CTM (16 of 77; 21%). Spinal MR imaging is helpful in premyelographic evaluation of SIH.

Cervical Spine MR Imaging Findings of Patients with Hirayama Disease in North America: A Multisite Study

The authors sought to determine if Hirayama disease in North America has the same imaging findings as it does in Asia. They assessed imaging studies in 21 patients and looked for loss of attachment of posterior dura, lower cord atrophy and high T2 signal, loss of cervical lordosis, and anterior dural shift in flexion. These 4 findings were able to discriminate patients from healthy controls. MR imaging findings in white North American patients with Hirayama disease include loss of attachment on neutral images and forward displacement of the dura with flexion. Findings are often present on neutral MR images and, in the appropriate clinical scenario, should prompt flexion MR imaging to evaluate anterior dural shift. BACKGROUND AND PURPOSE: Most studies of HD have been conducted in Asia, particularly Japan. To characterize the MR imaging findings of North American patients with HD, we reviewed neutral and flexion cervical MR imaging examinations performed for possible HD at 3 academic medical centers located in the Southeastern, Southwestern, and Midwestern regions of the United States. MATERIALS AND METHODS: Three neuroradiologists assessed the MR imaging examinations in a blinded fashion and reached a consensus rating for LOA of the posterior dura to the spine, lower spinal cord atrophy, spinal cord T2 hyperintensity, loss of cervical lordosis, anterior dural shift with flexion, and confidence of imaging diagnosis. Final reference diagnosis was established separately with a retrospective chart review by a neurologist. RESULTS: Twenty-one patients met the criteria for HD, all were North American males and all who reported their race were white. Seventeen patients did not meet the criteria and served as controls. Four imaging attributes, LOA, dural shift with flexion, consensus diagnosis of neutral images, and consensus diagnosis of combined neutral and flexion images were all able to discriminate the group with HD from the group without HD (P < .05 for each). Findings of HD were often present on neutral images, but the addition of flexion images increased diagnostic confidence. CONCLUSIONS: MR imaging findings in white North American patients with HD include LOA on neutral images and forward displacement of the dura with flexion. Findings are often present on neutral MR images and, in the appropriate clinical scenario, should prompt flexion MR imaging to evaluate anterior dural shift.

Chorea as a manifestation of spontaneous CSF leak

A 59-year-old man presented with orthostatic headaches, memory complaints, pronounced choreiform movements, and related hyperkinetic dysarthria and titubations. Head MRI findings were suggestive of CSF leak. CSF pressure was low. CT myelography documented CSF leak at the cervicothoracic junction. Targeted epidural blood patch led to resolution of symptoms, including complete disappearance of choreiform movements.

Ultrafast dynamic computed tomography myelography for the precise identification of high-flow cerebrospinal fluid leaks caused by spiculated spinal osteophytes

OBJECT Precise localization and understanding of the origin of spontaneous high-flow spinal CSF leaks is required prior to targeted treatment. This study demonstrates the utility of ultrafast dynamic CT myelography for the precise localization of high-flow CSF leaks caused by spiculated spinal osteophytes. METHODS This study reports a series of 14 patients with high-flow CSF leaks caused by spiculated spinal osteophytes who underwent ultrafast dynamic CT myelography between March 2009 and December 2010. There were 10 male and 4 female patients, with an average age of 49 years (range 37-74 years). The value of ultrafast dynamic CT myelography in depicting the CSF leak site was qualitatively assessed. RESULTS In all 14 patients, ultrafast dynamic CT myelography was technically successful at precisely demonstrating the site of the CSF leak, the causative spiculated osteophyte piercing the dura, and the relationship of the implicated osteophyte to adjacent structures. Leak sites included 3 cervical, 11 thoracic, and 0 lumbar levels, with 86% of the leaks occurring from C-5 to T-7. Information obtained from the ultrafast dynamic CT myelogram was considered useful in all treated CSF leaks. CONCLUSIONS Spinal osteophytes piercing the dura are a more frequent cause of high-flow CSF leaks than previously recognized. Ultrafast dynamic CT myelography adds value beyond standard dynamic myelography or digital subtraction myelography in the diagnosis and anatomical characterization of high-flow spinal CSF leaks caused by these osteophytes. This information allows for appropriate planning for percutaneous or surgical treatment.