| Sciatica: Studies of symptoms, genetic factors, and treatment with periradicular infiltration | ||
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The self-administered questionnaire items included education, estimation of physical workload, mental job stress, days on sick leave (only sick leaves related to the current sciatic episode), smoking, medical history (including back pain and sciatica) and history of current episode. Job status of those patients currently employed was characterized by a 3-scale classification (sedentary job, mixed job and physical job) (Ilmarinen et al. 1985). Every patient recorded his/her back pain and leg pain on 100-mm VAS scales and disability with the Oswestry Low Back Disability Questionnaire (Fairbank et al. 1980, Grönblad et al. 1993). The patients also estimated their quality-of-life on the Nottingham Health Profile (NHP), using its scale options ranging from 0 (best) to 100 (worst) (Koivukangas et al. 1995). In addition, every patient produced a pain drawing (Uden & Landin 1987).
Blood samples had been collected previously for genomic DNA extraction and analysed for sequence variations in the human COL9A1, COL9A2 and COL9A3 genes (Annunen et al. 1999, Paassilta et al. 1999, Pihlajamaa et al. 1999, Paassilta et al. 2001). The analysis consisted of PCR amplification of all exons and exon boundaries of the genes. The PCR products were subjected to CSGE analysis (Körkkö et al. 1998). Sequence variations observed in CSGE analysis as heteroduplexes were identified by automated sequencing (ABI PRISM™ 377 Sequencer and dRhod Dye Terminator Cycle Sequencing Kit, Perkin Elmer).
Mutation analysis of the 159 sciatic patients revealed 6 Trp2 allele positive cases (4 %), and 34 Trp3 allele positive cases among the remaining 153 sciatic patients (22%). Two of the Trp3 allele positive patients were homozygous for the allele.
The clinical examination took place within the week prior to MRI. The straight leg raising test of the ipsilateral (SLR) and contralateral legs (crossed SLR) was performed in the standard way, and the position where back or leg pain prevented further elevation was recorded with a goniometer to the nearest 5°. Lumbar flexion was measured by the modified Schober procedure (the difference between a 15-cm distance marked on the back of the patient in a standing position and the distance with the patient in full flexion). Sensory and motor defects, and tendon reflexes were examined. The dermatomal distribution of pain radiation was evaluated as normal: For L4 an area centred on the medial aspect of the lower leg; For L5 an area from the medial aspect of the foot across the dorsum of the foot and onto the lateral aspect of the lower leg; For S1 a band from the posterior sacrum along the entire posterior length of the lower limb and to the lateral aspect of the foot (Keegan & Garret 1948, Bogduk 1997a). Big toe extension weakness was used as an L5 root-specific test, abnormal patellar reflex as an L4 root-specific test, and missing ankle reflex as a S1 root-specific test (Agency for Health Care Policy and Research (AHCPR) 1994, Andersson & Deyo 1996).
MRI scans were obtained with a 1.5-T imaging system (Signa, General Electric, Milwaukee, Wisconsin) consisting of sagittal images with a repetition time (TR) of 4000 msec and echo time (TE) of 95 msec (T2-weighted) and axial images with a TR/TE of 640/14 msec (T1-weighted) before and immediately after intravenous injection of gadolinium-diethylenetriamine pentaacetic acid (0.1 mmol/kg Gd-DTPA, Magnevist, Schering, Berlin, Germany). Frequency-selected fat saturation was used for the postcontrast axial images. The technical specifications included a slice thickness of 4 mm with interslice gaps of 1.0 and 0.5 mm, a field of view of 30 and 20 cm for sagittal and axial images, respectively, and a matrix of 192 by 256/ two excitations (NEX). All images were read by two experienced MRI -radiologists blinded to the clinical status of the patients. In the case of any discrepancies between the radiologists, a consensus was reached before the final grading.
Disc displacement was graded as normal (grade 1); bulge (grade 2: a symmetrical extension of the peripheral annulus beyond the margins of the vertebral endplates); contained herniation (grade 3: a focal extrusion of disc material through the annulus but not through the posterior longitudinal ligament (PLL)); noncontained herniation (grade 4: an extrusion of disc material through the PLL); and sequester (grade 5: a disc fragment not in contact with the parent disc). Postcontrast enhancement of the nerve roots was regarded as positive if there was clear intraneural or perineural enhancement (compared to the contralateral asymptomatic root) distinct from the rim enhancement around the disc herniation. The extent of neural compromise was graded as none, minor (dislocation of the nerve root by disc herniation), or major (compression of the nerve root by disc herniation against the bony structures) according to Boos and co-workers (1995).
Intervertebral disc degeneration was graded normal (no signal changes); grade 1 (slight decrease in signal intensity of the nucleus on T2-weighted images); grade 2 (hypointense nucleus pulposus on T2-weighted images with normal disc height); and grade 3 (hypointense nucleus with disc space narrowing) (Stadnik et al. 1998). The end-plates and adjacent bone marrow were evaluated by Modic’s criteria (Modic et al. 1988). Schmorl’s nodes were evaluated from the sagittal scans (Takahashi et al. 1995). Intervertebral disc tears were evaluated from the posterior anulus fibrosus according Yu’s criteria (1989). A radial tear extended as a hyperintense line from the nucleus to the outer part of anulus fibrosus on T2-sequences, and with Gd-DTPA no enhancement was observed. Radial tears were evaluated only from nonherniated discs. A transverse tear was located in the outer part of anulus near either end-plate (Stadnik et al. 1998). High-intensity zone (HIZ) lesions were bright spots in the dorsal annulus on T2-weighted sagittal scans (Aprill & Bogduk 1992). The presence of thoracolumbar Scheuermann’s disease (TLS) was evaluated from the T2-weighted sagittal scans: disc space narrowing, disc dehydration, end-plate irregularities, wedging of anterior vertebral body margins, and Schmorl’s nodes in the thoracolumbar region. Either end-plate irregularities or Schmorl’s nodes and two of the other criteria at three or more disc levels from T10-11 to L3-4 had to be present for thoracolumbar Scheuermann (Heithoff et al. 1994).
ENMG was performed on every patient. H-reflexes of the tibialis posterior nerve and F-responses of the peroneus profundus nerve were measured on both sides. Muscles corresponding to root levels LIII-SI (vastus lateralis, tensor fasciae latae, semitendinosus, tibialis anterior, flexor hallucis longus, medial gastrocnemius, short head of biceps femori, and gluteus maximus) in the affected leg and paravertebral muscles down to multifidus were examined. The criteria for myelin damage were asymmetry of F-response of the peroneus profundus nerve and abnormality of H-reflex of the tibialis posterior nerve, in L5 and S1 nerve root irritation, respectively.
The symptomatic disc of each patient was evaluated in terms of clinical and ENMG findings. If no abnormalities were thereby detected, the symptomatic disc was evaluated solely on the basis of pain distribution (van Akkerveeken 1996). In addition, the neurophysiologist evaluated on the basis of pain drawing and ENMG if the sciatic pain experienced by each patient was radicular or nonradicular. Radicular pain is here defined as band-like dermatomal pain below the knee (Bogduk 1997a).