Archive for the ‘Neurology’ Category

Distinguishing true strokes from stroke mimics

September 21, 2016

Summary: This article provides the basis for a quick assessment of the likelihood of a stoke mimic, and therefore infers the likelihood of stroke. The score is not perfect. The presence of isolated sensory deficit at predicting a stroke mimic is interesting. The article does not state whether this finding is due to the presence of Bell’s palsies.

Patients: 784 patients (41% stroke mimics) in the emergency department who received MRI

Examiners: each patient was examined  by both a neurology house staff and a vascular neurologist

Examination method:

FABS (6 variables with 1 point for each variable present):

  1. absence of Facial droop,
  2. negative history of Atrial fibrillation,
  3. Age <50 years, systolic
  4. Blood pressure <150 mm Hg at presentation,
  5. history of Seizures, and
  6. isolated Sensory symptoms without weakness at presentation.

Reference standard: assessment by stroke team after MRI

Findings:

Accuracy for identifying
stroke mimics

Predictive value for
stroke mimics

(assuming 41% prevalence of stroke mimics)

Finding Sensitivity Specificity Positive predictive value Negative predictive value
Absence of a-fib

96

17

45

86

Presence of isolated sensory deficit

15

97

77

62

FABS≥3

90

91

87

93

Citation

Goyal N, Tsivgoulis G, Male S, Metter EJ, Iftikhar S, Kerro A, Chang JJ, Frey JL, Triantafyllou S, Papadimitropoulos G, Abedi V, Alexandrov AW, Alexandrov AV, & Zand R (2016). FABS: An Intuitive Tool for Screening of Stroke Mimics in the Emergency Department. Stroke; a journal of cerebral circulation, 47 (9), 2216-20 PMID: 27491733

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Signs of cervical spinal cord compression

August 18, 2011

This is a retrospective, unblinded  study of 120 patients without comorbidities undergoing laminoplasty for cervical myelopathy, defined as increased signal intensity (ISI) in T2-weighted magnetic resonance imaging (MRI).

On physical examination, the most sensitive findings were:

  • Hyperreflexia of knee 94%
  • Hoffmann reflex (“flexion of the ipsilateral thumb and/or index finger was considered as positive”) 81%
  • Babinski sign 53%
  • Ankle clonus 35%

These results are likely inflated due to lack of control group which prevented blinding.  In addition, the authors noted that the signs were less sensitive in patients with mild disability. Regardless, I suspect the relative values of the signs are correct and I was surprised on the value of the Hoffmann reflex.

Citation:

Chikuda H, Seichi A, Takeshita K, Shoda N, Ono T, Matsudaira K, Kawaguchi H, & Nakamura K (2010). Correlation between pyramidal signs and the severity of cervical myelopathy. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 19 (10), 1684-9 PMID: 20229121

Differentiating epileptic seizures and pseuodseizures

June 4, 2011

In a study of 120 events from 35 consecutive patients referred for video electroencephalography (VEEG) monitoring:

Video-documented predictors of psychogenic nonepileptic seizures were:

  • “preserved awareness,” “eye flutter,” and “bystanders can intensify or alleviate”)

Video-documented predictors of epileptic seizures were:

  • “abrupt onset,” “eye-opening/widening,” and postictal “confusion/sleep”

However, “eyewitness reports of these 6 signs were inaccurate and not statistically different from guessing.”

Digiti quinti sign for hemiparesis

February 11, 2011

Patients: Sixty patients with unilateral brain tumors without obvious focal signs and 30 controls

Examination: A physical therapist, blinded to all clinical and  imaging data, performed 13 clinical tests. A photograph of the digiti quinti sign is at http://pubmed.gov/20799429. In this test, the patient extends arms as for the pronator drift test, but turns palms down. In an abnormal test, the 5th finger on the weak side abducts more than the 5th finger on the normal side.

Outcome: MRI

Results:

Selected results from 13 tests that were studied.
Test Sensitivity Specificity
Digiti quinti sign 51% (41-61) 70% (61-79)
Pronator drifting test 41% (31-51) 96% (92-99)
Babinski sign 8%(2-14) 100%

Comment: this study used a case control design and so is subject to spectrum bias. However, restricting all patients to those without obvious focal signs may somewhat compensate.

This has been added to http://en.citizendium.org/wiki/Digiti_quinti_sign

Citation

Maranhão ET, Maranhão-Filho P, Lima MA, & Vincent MB (2010). Can clinical tests detect early signs of monohemispheric brain tumors? Journal of neurologic physical therapy : JNPT, 34 (3), 145-9 PMID: 20799429

Cervical neck rotation for headache diagnosis

January 14, 2011

Patients: The authors performed a cross sectional study of 60 patients who came from three groups of 20 patients: migraine headache, cervicogenic headache, and mixed headache.  The examiners were not aware of the patients’ diagnoses.

Examination: The cervical flexion–rotation test (FRT) maneuver “consisted of pre-positioning the cervical spine in maximal end range flexion followed by passive rotation of the head to the left and the right, with the subject relaxed in supine. End of range was determined either by firm resistance encountered by the therapist or the subject reporting the onset of pain, whichever came first.” The examination was done on a symptom-free day.

Results: The best cutoff with 30 degrees of rotation; patients with less than 30 degrees were more likely to have cervicogenic headache. The authors found that the area under the receiver operating characteristic curve was 0.85; however, the authors did not provide the sensitivity and specificity for that cutoff value.

Comment: The results of the study may be inflated. It is not clear whether the authors studied consecutive patients with headache or if the study was subject to spectrum bias. In addition, the patients with cervicogenic headache 10 years older which may influence cervical mobility.

Citation:

Hall TM, Briffa K, Hopper D, & Robinson K (2010). Comparative analysis and diagnostic accuracy of the cervical flexion-rotation test. The Journal of Headache and Pain, 11 (5), 391-7 PMID: 20508964

Diagnostic accuracy of confrontation visual field tests

April 28, 2010
Diagnostic accuracy of confrontation visual field tests
among 332 eyes with a prevalence of defects of 57%
Selected findings Sensitivity (%) Specificity (%) Kappa
Red comparison
77
27
0.74
Kinetic 5 mm red target
74
93
0.67
Finger comparison
71
57
0.69
Static finger wiggle
44
97
0.63
Finger counting
25
100
0.79

How to do the tests

  • Red comparison: “Two identical red atropine bottle tops, approximately 20 mm in diameter, were presented in a fashion analogous to the finger comparison test described above and the patient was asked if the bottle tops appeared equally red. Any quadrant in which the bottle top appeared less red was considered abnormal.”
  • Kinetic red target: “A 5-mm red-topped pin was moved inward from beyond the boundary of each quadrant along a line bisecting the horizontal and vertical meridians. The patient was asked to report when the pin was first perceived to be red.”
  • Finger comparison: “The examiner’s index fingers were presented simultaneously on either side of the vertical meridian in the superior and then inferior quadrants approximately 20° eccentric to fixation and the patient was asked to report if the fingers appeared equally clear. Any quadrant in which the finger appeared less clear was recorded as abnormal.”
  • Static finger wiggle: “Two index fingers were presented simultaneously on either side of the vertical meridian approximately 20° eccentric to fixation and equidistant from the quadrant borders in the superior and then inferior quadrants. The patient was asked to report which finger wiggled (<5° oscillation).”
  • Finger counting: “The patient was asked to count 1 or 2 static fingers presented sequentially in each of the 4 quadrants approximately 20° eccentric to fixation and equidistant from the quadrant borders.”

Reference

Kerr NM, Chew SS, Eady EK, Gamble GD, & Danesh-Meyer HV (2010). Diagnostic accuracy of confrontation visual field tests. Neurology, 74 (15), 1184-90 PMID: 20385890

Screening for dysphagia

October 20, 2009

ResearchBlogging.org

Dysphagia among stroke patients is suggested by the following test:

  1. First check the patient for “swallowing complaints, abnormalities of voice quality, facial asymmetry, or either expressive or receptive aphasia.” If none is detected then go to step 2.
  2. Have the patient drink 10 mL of water from a cup without a straw while seated upright while oxygenation saturation is monitored during and for 2 minutes after the test. Check whether the patient
    • “Coughed or choked during the water drinking or had a change in voice quality after the swallow”.
    • Oxygenation drops by 2% or more.

In this small study of 84 patients, this two-step test detected 96% of patients with dysphagia as compared to testing by a speech pathologist.

This had been added to http://en.citizendium.org/wiki/Dysphagia.

Citation:

Turner-Lawrence DE, Peebles M, Price MF, Singh SJ, & Asimos AW (2009). A feasibility study of the sensitivity of emergency physician Dysphagia screening in acute stroke patients. Annals of emergency medicine, 54 (3) PMID: 19362752

Screening for diabetic neuropathy

October 20, 2009

ResearchBlogging.orgThe preferred locations for testing according to this systematic review are filled green in the image. As the independent addition of the monofilament to visually inspecting for deformities, pressure marks, cracked skin, infected nails, evidence of prior ulcers, and other findings is not clear in the major trial of screening (http://pubmed.gov/8498761), it seems we should limit our time to testing three points rather than 10.footscreensites-rgb

This has been added to http://en.citizendium.org/wiki/Diabetic_neuropathy#Screening

Citation:

Feng Y, Schlösser FJ, & Sumpio BE (2009). The Semmes Weinstein monofilament examination as a screening tool for diabetic peripheral neuropathy. Journal of vascular surgery : official publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter, 50 (3) PMID: 19595541

Postural hypotension in patients with syncope

September 18, 2009
ResearchBlogging.org Arch Intern Med 2009 PMID: 19636031

The authors report that in 2106 consecutive patients 65 years or older admitted for syncope, “Postural blood pressure (BP) recording, performed in only 38% of episodes, had the highest yield with respect to affecting diagnosis (18%-26%) or management (25%-30%) and determining etiology of the syncopal episode (15%-21%).”

  • The lower percentages are based on ‘strict criteria’ for abnormal changes:
    • drop in systolic BP of at least 20 mm Hg
    • or
    • drop in diastolic BP of at least 10 mm Hg
  • The higher percentages are based on ‘loose criteria’ for abnormal changes:
    • drop in systolic or diastolic BP of at least 10 mm Hg
    • or
    • systolic BP drop to 90 mm Hg or lower

A systematic review of postural blood pressure measurements has been published by the Rational Clinical Examination (McGee S, Abernethy WB, Simel DL The rational clinical examination. Is this patient hypovolemic? JAMA 1999;281 (11):1022-9. DOI:10.1001/jama.281.11.1022 PMID: 10086438 ) Their meta-analysis concluded that the following changes may occur in normal, euvolemic adults:

  • Pulse increase:11 (95CI: 9-13mm Hg)
  • Systolic blood pressure drop: 4 (95CI: 2 – 6mm Hg)
  • Diastolic blood pressure drop: 5 (95CI: 3 – 8 mm Hg)

Based on the Rational Clinical Examination review, which reveals how difficult it is to interpret orthostatic vital signs and that we cannot simply dichotomize the results into normal and abnormal, I think the strict criteria are better. Even with these criteria, orthostatic vital signs was the most important part of the evaluation for syncope.

This has been added to http://en.citizendium.org/wiki/Syncope and http://wiki.medpedia.com/Clinical:Syncope.

Citation:
Mendu ML, McAvay G, Lampert R, Stoehr J, & Tinetti ME (2009). Yield of diagnostic tests in evaluating syncopal episodes in older patients. Archives of Internal Medicine, 169 (14), 1299-305 PMID: 19636031