Archive for the ‘Uncategorized’ Category

Diagnosing lumbar nerve root compression at the bedside

January 25, 2019

Summary: This article finds that the accuracy of the clinical exam (by a very expert clinician) depends on the location of the nerve deficit. For nerve root compression by a disc, the SLUMP and SLR dynamic tests were most sensitive. However, for foraminal compression, which was the most common site, the dynamic tests have less than 50% sensitivity. The presence of any one neurologic deficit (motor, sensory, or reflex) had sensitivities of 90% and 80% for disc and foraminal high-grade compression, respectively. In no analysis was the positive predictive value over 50% – in spite of the high prevalence of compression in this referred population. All patients had at least low-grade nerve compression.

A practical finding is that in the absence of nerve deficits (motor, sensory, or reflect), high-grade nerve compression is unlikely although some high-grade foraminal compression is possible.

Patients: 99 adults who were referred for transforaminal epidural steroid injection from the orthopedic clinic at a single hospital in the south of Sweden. The patients were classified into 3 groups of nerve compression:

  • Low-grade nerve compression (m=61): “neither high-grade subarticular nor high-grade foraminal nerve compression”
  • High-grade subarticular nerve compression (n=14)
  • High-grade foraminal nerve compression (n=25)

One subject was included in both of the latter groups

Examiners: An “experienced physiotherapist … who was blinded to all MRI information.”

Examination method:

Radiculopathy I “was considered when one of the neurologic signs above* was present and corresponded to the nerve root” of the planned injection.

* “patellar reflex, Achilles’ reflex, strength of the large toe in dorsiflexion, or sensibility (sensory deficit) in a specific dermatome area was asymmetrically deranged”

Radiculopathy II “was considered when 2 neurologic signs (sensory deficit + reflex impairment or muscle weakness) were present and corresponded” to the site of the planned injection.

The straight-leg raise test “performed with the patient supine according to the published instructions. The straight leg was slowly raised and the test was classified as positive or negative, using sensitizing maneuvers, beginning with the ankle and continuing with the neck.”

The slump test “was performed with the patient sitting and was assessed through a combination of sitting thoracolumbar flexion, cervical flexion, ankle dorsiflexion, and knee extension. With the use of sensitizing maneuvers, beginning with the ankle and continuing with the neck, the test was considered positive if one of the maneuvers reproduced the symptoms and the symptoms were different from the contralateral side.”

The femoral stretch test was “performed with the patient side-lying on the nonaffected side, assesses the presence/absence of neural mechanosensitivity (L2-4) using a combination of thoracolumbar flexion, cervical flexion, knee flexion, and hip extension. The test was classified as positive or negative, using sensitizing maneuvers, beginning with the knee and continuing with the neck. The test was considered positive if one of the maneuvers reproduced the symptoms and the symptoms were different from the contralateral side”.

Reference standard:

MRI for

  • Disk protrusion or extrusion
  • Subarticular nerve compression by a disc was assessed on axial T2-weighted images (PMID 21539702). High-grade compression required “periradicular cerebrospinal fluid or fat is obliterated”
  • Foraminal nerve compression assess on sagittal T1-weighted images (PMID 20308517). High-grade compression required “distortion or other morphologic change in the nerve root.”

Findings:

All patients had nerve compression:

  • Disc:  low-grade (n=85) and high-grade (n=14)
  • Foraminal : low-grade (n=74) and high-grade (n=25)

High-grade subarticular nerve root compression

L2-S1 (N=99) Sens Spec PPV NPV
Pos slump test 1.00 .38 .21 1.00
Pos SLR test 0.93 .57 .26 0.98
Radiculopathy I 0.93 .34 .19 0.97
Radiculopathy II 0.71 .73 .30 0.94
L2–4 (n=18)
Pos femoral stretch test 1.00 .65 .14 1.00

High-grade foraminal nerve root compression

L2-S1 (N=99) Sens Spec AUC PPV NPV
Pos slump test .48 .26 .37 .18 .59
Pos SLR test .32 .43 .38 .16 .65
Radiculopathy I .80 .34 .57 .29 .83
Radiculopathy II .28 .65 .47 .21 .73
L2-4 (n=18)
Pos femoral stretch test .17 .50 .33 .14 .55

An addition table not shown is the analysis of disk extrusion.

Citation

1. Ekedahl H, Jönsson B, Annertz M, Frobell RB. Accuracy of Clinical Tests in
Detecting Disk Herniation and Nerve Root Compression in Subjects With Lumbar
Radicular Symptoms. Arch Phys Med Rehabil. 2018 Apr;99(4):726-735. doi:
10.1016/j.apmr.2017.11.006. PMID: 29253501.
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Distinguishing neuropathic pain from nocioceptive pain

January 23, 2014
This study quantifies the value of the history among 269 patients with chronic pain in three pain clinics.

Summary:

  • Neither their survey nor any individual findings were strong enough to hang one’s hat on.
  • The most helpful finding when present was a sensation of brushing.
  • The most helpful finding when absent was numbness.

 Methods:

  • Patients: 196 patients in whom two physicians agreed on the basis of the pain. Excluded were 106 patients for whom the physicians agreed that the pain had a mixed basis or for whom the physicians did not agree whether the pain was neuropathic.
  • Gold standard: consensus assessment by two physicians of the basis of the pain.

Findings:

Accuracy

Predictive value
(assuming equal pretest probabilities of neuropathic and nocioceptive pain)

Finding Sensitivity Specificity Positive predictive value Negative predictive value
DN4 7-item survey(score 4 or more)

74

79

78

75

Numbness sensation

74

68

70

73

Painful cold sensation

64

80

76

69

Brushing sensation

51

91

85

65

Citation

van Seventer R, Vos C, Giezeman M, Meerding WJ, Arnould B, Regnault A, van Eerd M, Martin C, & Huygen F (2013). Validation of the Dutch version of the DN4 diagnostic questionnaire for neuropathic pain. Pain practice : the official journal of World Institute of Pain, 13 (5), 390-8 PMID: 23113981

Physical examination for detection of anemia

September 23, 2012
Twelve primary health care providers in Bangladesh examined 452 pregnant women (198 had Hb < 10) for the presence or absence of pallor on nine different anatomical sites, viz. nail-beds, nail-bed blanching, palm, palmar creases, face, lips, tongue, oral mucosa and conjunctiva
Below is a table (larger version is here) of the standardized colors the researchers used and the distribution of results for the conjunctival color.

Two other studies on this topic, all with different results are PMID 2297289 and 20049324

Distribution of color of the everted lower eyelid.
1 2 3 4 5 6 7 8 9 10 11 12 13
Hb < 10 28% 42% 36%
Hb 10 – 12 19% 19% 40%
Hb > 12 10% 53% Not
stated
Not
stated
Not
stated

References

Chowdhury ME, Chongsuvivatwong V, Geater AF, Akhter HH, & Winn T (2002). Taking a medical history and using a colour scale during clinical examination of pallor improves detection of anaemia. Tropical medicine & international health : TM & IH, 7 (2), 133-9 PMID: 11841703

Hoover’s sign for the diagnosis of functional weakness

March 29, 2012

In a study of 124 patients with suspected stroke who presented with leg weakness, clinical evaluation ultimately determined that in eight patients (6%) the weakness was functional.

For functional weakness:

Sensitivity Specificity Predictive values at prevalence of 6%
Positive Negative
Hoover’s sign* 63%
(95% CI: 24 to 91)
100%
(95% CI: 97 to 100)
100% 3%
* “was considered positive when there was weakness of voluntary hip extension in the presence of normal involuntary hip extension during contralateral hip flexion against resistance”.
Of note, the abductor sign is an alternative test for functional weakness. (PMID: 14707320)

Citation

McWhirter L, Stone J, Sandercock P, & Whiteley W (2011). Hoover’s sign for the diagnosis of functional weakness: a prospective unblinded cohort study in patients with suspected stroke. Journal of psychosomatic research, 71 (6), 384-6 PMID: 22118379

A “mini” Mini-Mental State Examination

July 15, 2011

The authors propose a six item screener (SIS) that contains six items from the Mini-Mental State Examination (MMSE):

The examiner first asks the patient to remember three items: GRASS PAPER SHOE. The examiner could repeat the words 3 times as needed to help the patient.

  • Orientation to time
    1. Year
    2. Month
    3. Day of the week
  • Recall of three items (one point each)

Patients: The authors studied 371 patients in the emergency room after excluding 587 patients, mostly due to having received sedating medications.

Results: As compared to the full MMSE, the accuracy of the SIS was:

  • Sensitivity 74%
  • Specificity 77%

Citation:

Carpenter CR, Despain B, Keeling TN, Shah M, & Rothenberger M (2011). The Six-Item Screener and AD8 for the Detection of Cognitive Impairment in Geriatric Emergency Department Patients. Annals of emergency medicine, 57 (6), 653-61 PMID: 20855129

Measuring the ankle-brachial index using a stethoscope

February 25, 2009

Can we measure the ankle-brachial index using only a stethoscope? A pilot study. Fam Pract. 2009 Feb;26(1):22-6. Epub 2008 Nov 20. PMID: 19022870

The ankle-brachial index (ABI) by ausculation is less sensitive than an ABI of less than 0.9 by doppler ultrasonography and is less sensitive than an earlier report of the ABI by palpation.

Patients:

Test:

Reference standard:

Accuracy:

Last year, a study reported that the ankle-brachial index by palpation has a sensitivity and specificity of 88% and 82%, respectively as compared to handheld Doppler ultrasonography (PMID 18567610).

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