Study of the relationship and importance of clinical semiology, axial computed tomography and electroneuromyography in lumbar radioculopathies

Estudo da relação e da importância entre a semiologia clínica, tomografia axial computadorizada e eletroneuromiografia nas radiculopatias lombares

Study of the relationship and importance of clinical semiology, axial computed tomography and electroneuromyography in lumbar radioculopathies

Estudo da relação e da importância entre a semiologia clínica, tomografia axial computadorizada e eletroneuromiografia nas radiculopatias lombares

Emílio Cezar Mamede Murade^I; José Soares Hungria Neto^II; Osmar Avanzi^II

^IPost graduate

^IIAdjunct Professor

^{Address for correspondence}

SUMMARY

The authors evaluated forty-three patients with clinical suspect of lumbar radiculopathy caused by disk hernia, concerning to clinical semiology, computed tomography and electromyography were studied and their correlations. The clinical semiology was altered in 100,0% of the patients, the computed tomography in 90,7% and the electromyography in 88,7%. The correlation among the three exams didn´t show any prevalency among any of the possible associations. The authors emphasize the importance of clinical semiology, computed tomography and electromyography for a more accurate diagnosis of lumbar radiculopathy following by disk hernia.

Key words: Lumbar radiculopathy; clinical semiology; tomography axial computed; electroneuromyography.

RESUMO

Os autores estudaram 43 pacientes com suspeita clínica de radiculopatia lombar, causada por hérnia de disco, relacionando os achados da semiologia clínica, tomografia axial computadorizada e eletroneuromiografia, entre si. A semiologia clínica estava alterada em 100,0% dos pacientes, a tomografia axial computadorizada em 90,7% e a eletroneuromiografia em 88,7%. A correlação entre os três exames não mostrou prevalência entre nenhuma associação. Os autores enfatizam a importância da semiologia clínica, tomografia axial computadorizada e eletroneuromiografia para maior exatidão diagnóstica das radiculopatias lombares por hérnia de disco.

Descritores: Radiculopatias lombares; semiologia clínica; tomografia axial computadorizada; eletroneuromiografia.

INTRODUCTION

Lumbar radiculopathy is frequentally among us, and has variable symptoms and frequently presents with lumbo-sciatalgia, that is a clinical picture of lumbar or lumbo-sacral pain with irradiation to the lower limbs and may or not be joined by scoliosis attitude and/or sensitive and/or motor changes which can appear according to the affected root.

Clinical history, physical examination, discography, myelography, phlebography, axial computed tomography and, more recently, magnetic resonance have been shown to be very exact for anatomical identification of the lumbar disc hernia. The diagnosis becomes clear with evaluation of these tests, however no one of them is able to precisely assess the degree of root involvement.

Early and precise diagnosis is necessary for starting treatment, avoiding progression to a palsy, with our without possibility of reversibility due to even with correct treatment.

The aim of this work was to evaluate the correlation between clinical findings (clinical history and physical examination) with results from axial computed tomography and electroneuromyography in patients with a suspected root involvement due to lumbar disc hernia.

MATERIAL AND METHOD

This work was based on the analysis of 43 patients seen from March 1991 to January 1996 with suspected lumbar radiculopathy (due to disc herniation).

From the 43 patients, 26 (60.5%) were male and 17 (39.5%) female, with ages ranging from 16 to 74 years.

All patients underwent anamnesis, physical examination and axial computed tomography. In order to confirm findings and diagnostic hypothesis, electroneuromyography (ENMG) was performed without previous information of the CT scans results.

a) Clinical Semiology

The study of the patients with a suggestive clinical picture of lumbar disc hernia followed a trial protocol with an order number, patient initials, age, gender, main complaint, history of the current disease, physical examination, affected side, antalgic attitude, area of pain irradiation, sensitivity changes (tactile and painful), changes in strength (versus opposition force and test with load), Lasègue's maneuver, Wassermann-Boschi's maneuver, Valsalva's maneuver, pulses and clinical diagnosis hypothesis.

The right side was affected in 16 (37.2%) of the patients, the left side in 23 (53.5%) and in four (9.3%) both sides were affected.

The tested reflexes were: patellar for L4 root, Achilean for S1 and considered as positive when increased, reduced or absent.

Sensitivity tests were performed in the dermatomes according to KEGAN's (1943) diagram with tactile evaluation (brush) and pain evaluation (needle), comparatively and noted changes such as hypoesthesia, anesthesia, and hyperesthesia in the corresponding dermatomes.

Changes in muscle strength were rated as M0 — no contraction; M1 — visible or palpable contraction; M2 — contraction is present and able to overcome gravity however not able to overcome counterforce; M3 — contraction is present and is able to overcome counterforce and gravity; M4 — useful contraction, overcomes counterforce and gravity; M5 — normal contraction. The examined muscles, according to Marinacci diagram, were quadriceps for L4, anterior tibial and long extensor of hallux for L5, and gastrocnemius for S1.

Specially tested maneuvers were: a) Lasègue's, performed being the patient in supine position and considered as positive when causing pain irradiated to the lower limb, similar to the pain of the patient's complaint (in the dermatome of the affected root); b) Wassermann-Boschi's, used to evaluate higher roots (L1, L2 and L3), tested the patient being in prone position and considered as positive when the patient reported pain in the corresponding dermatomes; c) Valsalva's (increased intrathecal pressure); this maneuver is positive when disc hernia causes pressure over the dural sac, that with increased intrathecal pressure promotes pressure over the root, causing pain that is lumbar or irradiated to the affected limb. Similar to Lasègue's maneuver, Valsalva's can be negative when the protrusion is foraminal of extra-foraminal.

In regard of the changes in physical examination (change in strength, change in sensitivity and reflexes, Lasègue's, Wassermann-Boschi and/or Valsalva's maneuvers) patients presenting two or more positive items were considered as probably bearing radiculopathy due to lumbar disc hernia and included in the protocol.

From the changes in the physical examination, were considered as positive for L4: change in strength of quadriceps, changes in patellar reflex, in anterior-medial leg aspect sensitivity, positive Wassermann-Boschi and/or Valsalva's maneuvers; for L5: change in strength of anterior tibial and long extensor of the hallux muscles, changes in anterior-lateral leg aspect sensitivity, positive Lasègue's and/or Valsalva's maneuvers, load test for anterior tibial (there is no reflex available for this root). For S1, changes in gastrocnemius' strength, changes in Achilean reflex, changes in posterior leg aspect sensitivity, and positive Lasègue and/or Valsalva's maneuvers.

b) Radiographic study

After physical examination was performed, the patients underwent radiographic spinal tests in anterior and lateral views, and in some cases, oblique, in order to evidence other associated or related to the clinical picture changes.

Radiographic changes considered as positive were: reduction of thickness of intervertebral disc, "fulcrum" intervertebral sign, signs of ostearthrosis (articular facets hypertrophy), anterior and/or posterior marginal osteophyte.

Following, patients underwent axial computed tomography (CT scan) of lumbo-sacral spine, with 5 mm thick slices and spaced by 3 mm, involving vertebral pedicula, vertebral body and intervertebral disc.

Tomography criteria for lumbar disc hernia location were: central, central-lateral, foraminal and extra-foraminal, and the level.

Changes in CT scan, when located at L3-L4 space were associated to involvement of L4; in L4-L5, L5 root and L5-S1 for S1.

c) Electroneuromiographic study

ENMG was performed in patients (whose clinical picture already suggested root involvement by disc hernia) through nervous conduction study both motor and sensitive (ENG) and muscle evaluation (EMG). ENMG was performed in two phases: a) electroneurography — nervous conduction and late response; b) electronmiography — positive waves, fibrillations, polyphasic potentials, and interference pattern in maximum contraction.

Motor electroneurography was performed in tibial and fibular nerves, with stimuli at knee and ankle, and readings in abductor of fifth toe muscle (tibial nerve) and extensor of short toes (fibular nerve), and sensitive electroneurography at sural nerve.

Electroneurography has usually no changes in cases of lumbar hernia. When changed, comparative to the upper limbs tests were used to differentiate from other diseases such as peripheral polyneuropathy or other conduction velocity modifying diseases.

Electronmiographic study was performed bilaterally with monopolar needles and tests in paravertebral, semi-tendinous, long fibular, anterior tibial, gastrocnemius (medial head), abductor of fifth toe, and short extensor of the toes, tested at rest, with light contraction and with maximum contraction.

Were considered as positive electroneuromiographic changes with signs of denervation at rest (fibrillations and positive waves), polyphasic action potentials at minimal contraction, and rarefaction of interference pattern at maximum contraction.

Whenever changes affected paravertebral, gastrocnemius and abductor of the fifth toe muscles, they were considered as due to S1 involvement; whenever the affected muscles were paravertebral, anterior tibial, long fibular and short extensor of the toes, they were considered as related to L5; and when the changes were in quadriceps and fascia lata tensor, L4.

In investigation of late responses (F wave and H reflex), findings of F wave for tibial and fibular nerves, and H reflex for tibial nerve were considered as positive when there was a larger than 2.0 milliseconds increase in comparison to counter lateral results.

When late response change (F wave) was only for the fibular nerve, it was considered as related to L5; when the F wave was found for the tibial nerve and/or H reflex were changed, it was considered linked to S1.

RESULTS

Patellar and/or Achilean reflexes were found changed in 22 patients (51.2%), with increase in two, absence in five and reduction in the 15 remaining patients. Sensitivity changes were found in 38 patients (88.4%).

Strength evaluation was changed in 38 patients (88.4%) and the load test was positive in 35 patients (81.4%).

Lasègue's maneuver was positive in 32 patients (74.4%) and Wassermann-Boschi's was positive in nine patients (20.9%). In three patients Lasègue's and Wassermann-Boschi's maneuvers were simultaneously positive. Valsalva's maneuver was positive in 11 patients (27.9%).

Changes in physical examination were related to the different roots as follows: 8 (18.6%) patients for L4; 22 (51.1%) for L5; 11 (25.6%) for S1 and two (4.7%) more than one root.

From the 43 patients who underwent TC scan, 39 (90.7%) had abnormalities, which were distributed according to location as: 11 (25.6%) central protrusion; 19 (44.2%) central-lateral; 7 (16.2%) lateral; one (2.3%) extra-foraminal; one (2.3%) canal stenosis; and four (9.4%) without changes.

In regard to the affected space, CT scan demonstrated: 9 (20.9%) L3-L4; 23 (53.5%) L4-L5; 6 (14.0%) L5-S1 and 4 (9.3%) with no detected changes.

From changes found in electroneuromiography, in 2 (4.6%) patients nervous conduction was changed, in 28 (65.1%) patients late responses (F wave and/or H reflex) were changed and in 36 (83.7%) patients it was electromyography that was changed.

Regarding involved roots, ENMG had: 7 (16.3%) of L4; 19 (44.3%) of L5; 9 (20.9%) of S1; in three patients (7.0%) the found changes were diagnosed as not radicular.

The results of physical examination, CT scan and ENMG from the 43 patients were correlated as pairs and between the three of them.

Agreement between physical examination and CT scan was found in 34 of the patients. The (Table 1) displays the distribution of the affected roots.

Correlation between physical examination and ENMG, had an agreement in 35 981.4%) patients, and the distribution in regard to the involved roots is displayed in (Table 2).

Correlation between CT scan and ENMG, had agreement in 31 patients (72.1%) and the distribution of the affected roots is in (Table 3).

Analysis of correlation between the three different evaluations had agreement in 28 patients (65.1%) and the distribution according to the roots is in (Table 4).

Considering physical examination as gold-standard for positive changes (close to 100% of accuracy) and comparing it to the other tests, the findings demonstrated a sensitivity of 90.7% in relation to CT, 88.4% in relation to ENMG and 81.4% when comparing the three tests.

DISCUSSION

DANDY (1941) apud FINESCHI⁽⁷⁾ stated that, for diagnosis of lumbosciatalgia due to lumbar disc hernia only clinical history, physical examination and a plain radiograph were enough. In our study we could find that these parameters are insufficient to exactly identify the place and intensity of the commitment, and separate from other diseases that can be confused with lumbosciatalgia due to disc hernia.

Radiographic changes may not indicate the severity of a root commitment and its prognosis. Some of these changes are important, however may present without symptoms.

Demonstrated^(4,9) a high positive index of Lasègue's maneuver (80% and 86%, respectively). The trial was performed in patients with disc hernia in L4-L5 and L5-S1 spaces.

In our study Lasègue's maneuver was positive in 74.4% of the patients, being considered as positive from 30° to 60°. From the patients with negative Lasègue's maneuver, five had involvement of L4, in whose it was expected a negative maneuver, two patients had a centralized disc hernia (one patient with lateral and another with central-lateral).

Wassermann-Boschi's maneuver, that corresponds to Lasègue for higher roots, was positive in nine patients.

Changes in strength and sensitivity were positive in 88.0% and the correspondence between the dermatome and the affected root was close to 100%. In regard of findings in physical examination and the affected root: L5, with 51.1% of the patients was the most frequently involved root. Presented similar results^(11,14).

From the changes found in physical examination, sensitivity and Lasègue's maneuver are the most evident and important, for giving the sensitive distribution of the affected root and presupposing hernia location. If the compression is central or central-lateral, Lasègue's maneuver will be positive.

Evaluating CT scans of the patients we could exactly determine the anatomical location of the disc hernia, its location in medullar canal and its magnitude. CT is superior to myelography and discography for demonstration of lateral and extra-foraminal hernias.

By means^(5,6) of CT scan for diagnosis of lumbar disc hernias, judged this test to be risks free, with a large number of correct results and the best. Other authors, as WILLIANS et al. ¹⁶ indicate CT scan as first choice test in diagnosing lumbar disc hernias, due to its high specificity, sensitivity and accuracy.

In our study, clinical history, physical examination and CT scan agreed in 79.1% of the cases, however are insufficient for demonstrating the intensity of radicular commitment, being other exams necessary for evaluation of the lesion degree and prognosis.

ENMG was shown to be a very important complementary exam, for it allows definition, in multiple protrusions, which one is the one that is causing root involvement, and the severity of the disease. Conversely to what WATKINS⁽¹⁵⁾ stated, ENMG can exactly determine which root is involved.

KNUTSSON⁽¹¹⁾ informed that ENMG was positive in 80% of his patients, and that the most affected root was L5. In our work, ENMG was positive in 83.7%, and L5 was the most affected root.

JOHNSON & MELVIN⁽⁸⁾ showed that in 30% of their patients, ENMG changes were positive waves and fibrillation only in paravertebral muscles.

All patients in our study underwent test in paravertebral muscles. We found six (15.7%) patients with positive changes only in paravertebral muscles.

Studied late responses (F wave and H reflex) and considered these changes as positive when differences between right and left side were larger than 2.0 milliseconds for F wave and larger than 1.0 millisecond for H reflex^{(1,2,3,10,12)}.

In our study, changes in latency larger than 1.5 milliseconds for H reflex and 2.0 milliseconds for F wave, were considered as positives. We found 65.1% of late response changes, and for patients with S1 commitment, changes in H reflex were of 75% and in patients with L5 commitment, F waves were altered in 84.1%.

In his thesis demonstrated that ENMG is an excellent test in lumbar root pathology, and that the accuracy increases when associated to other diagnosis techniques⁽¹³⁾.

From the correlation between ENMG and CT we found 71.4% of agreement in regard of the affected roots. In the 11 that disagreed, two were due to CT diagnosis mistakes, one due to ENM mistake, and four due to the location of the hernia; and four disagreed in regard of the diagnosis (myelopathy and peripheric polyneuropathy).

In our four cases where ENMG and CT disagreed, in three patients ENMG had changes for S1 and CT showed a centralized hernia of the L4-L5 level, and one had a positive ENMG for L5 and CT an extra-foraminal hernia of L5-S1. These phenomena can be explained by anatomical situation.

SANTINI & PITTO⁽¹⁴⁾ considered the extra-foraminal disc hernia as of rare incidence and as one of the causes of surgical treatment failure due to mistakes in surgical exploration. CT scan would confirm the extra-foraminal compression. In his patients, the incidence was of two in the space L4-L5 and three in the space L5-S1.

The clinical picture, CT scan, and ENMG are well defined and conclusive tests for diagnosis of lumbar radiculopathies, and should complement each other in cases of lumbar disc hernia, mostly in those cases with poor evolution or with indication of surgical treatment.

CONCLUSIONS

1) In our study, correlation of CT scan results and physical examination for diagnosis of lumbar radiculopathy due to disc hernia was positive in 79.1%.

2) Agreement between physical examination and ENMG was of 81.4%.

3) In the correlation between CT scan and ENMG, the findings agreed in 72.1%.

4) Agreement between the three tests was of 65.1%.

5) We can conclude that the correlations between the tests did not show any of them to prevail.

6) We suggest that in routine diagnosis it should be correlated clinical semiology, CT scan and ENMG for granting a better and precise diagnosis of lumbar radiculopathy due to disc herniation.

7) The results of this study may serve as a basis for evaluation of diagnosis accuracy of the presented cases with those of the performed treatments.

Trabalho recebido em 13/05/2002. Aprovado em 28/06/2002

Work performed at Departamento de Ortopedia e Traumatologia da Santa Casa

de São Paulo - São Paulo - SP

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Publication Dates

• Publication in this collection
  25 Feb 2003
• Date of issue
  Dec 2002

History

• Accepted
  28 June 2002
• Received
  13 May 2002