Posterior tibial and sural nerve somatosensory evoked potentials: a study in spastic paraparesis and spinal cord lesions

Who is going to walk? A review of the factors influencing walking recovery after spinal cord injury

The recovery of walking function is considered of extreme relevance both by patients and physicians. Consequently, in the recent years, recovery of locomotion become a major objective of new pharmacological and rehabilitative interventions. In the last decade, several pharmacological treatment and rehabilitative approaches have been initiated to enhance locomotion capacity of SCI patients. Basic science advances in regeneration of the central nervous system hold promise of further neurological and functional recovery to be studied in clinical trials. Therefore, a precise knowledge of the natural course of walking recovery after SCI and of the factors affecting the prognosis for recovery has become mandatory. In the present work we reviewed the prognostic factors for walking recovery, with particular attention paid to the clinical ones (neurological examination at admission, age, etiology gender, time course of recovery). The prognostic value of some instrumental examinations has also been reviewed. Based on these factors we suggest that a reliable prognosis for walking recovery is possible. Instrumental examinations, in particular evoked potentials could be useful to improve the prognosis.

Segmental abdominal wall paresis caused by lateral low thoracic disc herniation

STUDY DESIGN

Clinical, radiologic, and neurophysiologic description of 2 cases.

OBJECTIVE

To describe 2 cases with spontaneous deep unilateral abdominal pain as the first symptom of thoracic disc herniation at a low thoracic vertebral level, further manifested by unilateral partial paresis of the obliquus abdominis muscle.

SUMMARY OF BACKGROUND DATA

Clinical manifestation of lateral thoracic disc herniation with electrophysiologic results and conservative therapy as treatment of choice when spinal cord functions are preserved.

METHODS

Magnetic resonance imaging revealed bilateral paramedian disc protrusions at T12-L1 in Patient 1 and foraminal herniation at T10-T11 and paramedian herniation at T11-T12 in Patient 2. Electromyography (EMG) and evoked potentials were investigated in the acute stage and after 6 months.

RESULTS

Spontaneous activity on needle EMG confirmed axonal root impairment. Somatosensory and motor-evoked potentials were within normal limits and excluded spinal cord involvement. Nonsteroidal anti-inflammatory drugs and periradicular injection of steroids and local anesthetics rendered both patients pain-free. Normalization of muscle strength within 3 to 6 months was accompanied by EMG findings of reinnervation.

CONCLUSION

Lateral disc herniation causing compression of a thoracic root associated with unilateral segmental paresis of the abdominal wall is a rare condition. Despite EMG documentation of axonal root lesion, however, a purely conservative therapeutic approach may be considered treatment of choice in cases without spinal cord involvement.

Motor and somatosensory evoked potentials in Autosomal Dominant Hereditary Spastic Paraparesis (ADHSP) linked to chromosome 2p, SPG4

The aim of our study was to evaluate Motor Evoked Potentials (MEPs) and cortical excitability, using Transcranial Magnetic Stimulation (TMS) as well as short latency Somatosensory Evoked Potentials (SEPs) in Autosomal Dominant Hereditary Spastic Paraparesis (ADHSP) patients. MEPs were recorded from upper and lower limb muscles in 12 patients (7 m and 5f) affected by ADHSP with spastin mutation (SPG4). We measured: (i) motor threshold (MTh); (ii) total motor conduction time (TMCT); (iii) direct and indirect central motor conduction time (d-CMCT and i-CMCT) calculated by subtracting from the cortical latency those obtained on magnetic spinal stimulation (d-PMCT) and via the F-wave method (i-PMCT); (iv) MEP amplitude (MEP/Mmax ratio%) and (v) duration of the cortical silent period (CSP). Latency, amplitude and persistence of the F-wave obtained with electrical nerve stimulation were also considered; H reflex was also tested from lower extremities. SEPs were recorded from spine and scalp sites following median and posterior tibial nerve stimulation; conventional latency and amplitude measurements were performed. In a comparison with the control group, the MTh recording from lower limbs was significantly higher (67.5 +/- 7.7% versus 52.5 +/- 6.9%), MEPs were absent in one case and showed reduced amplitude in the remainders (22.9 +/- 12.6% versus 66.3 +/- 25.9% of M wave); TMCT resulted to be abnormal (36.5 +/- 3.9 ms versus 27.1 +/- 1.4 ms) and d-CMCT as well as i-CMCT were significantly prolonged (23.1 +/- 3.5 ms versus 13.8 +/- 1.3 ms; and 20.1 +/- 3.4 ms versus 10.6 +/- 1.3 ms, respectively). The CSP, which was normal from the hands, was significantly shortened from the legs and correlated with spasticity scoring (Ashworth scale). Cortical SEPs from lower limbs were abnormal in all cases, whereas SEPs by stimulation of median nerves were normal; F-wave parameters from upper limbs showed no abnormalities, whereas an increased persistence was detected from lower limbs; H reflex amplitudes resulted larger compared with controls. Moreover, shortening of the CSP, being correlated with the Ashworth scale, can be considered an electrophysiological marker of spasticity that seems to arise from impairment of the supraspinal or intracortical inhibitory pathways with an additional contribution of increased segmental motor neuron excitability. These data prove the existence of comparable neurophysiological abnormalities in ADHSP with spastin mutation (SPG4) when long ascending and descending pathways are involved.

The effect of spasticity on cortical somatosensory-evoked potentials: changes of cortical somatosensory-evoked potentials after botulinum toxin type A injection

OBJECTIVE

To evaluate the changes in cortical somatosensory-evoked potentials (SEPs) after botulinum toxin type A injection to determine what effect spasticity has on cortical SEPs.

DESIGN

Intervention study and before-after trial.

SETTING

University-affiliated hospital in Korea.

PARTICIPANTS

Twelve children with spastic hemiplegic cerebral palsy (CP), 7 children with spastic diplegic CP, and 8 patients with traumatic brain injury.

INTERVENTION

All participants had botulinum toxin type A injected into the muscles of the spastic limb.

MAIN OUTCOME MEASURES

SEPs were recorded before and 7 days after the botulinum toxin type A injection. Spasticity of the affected spastic limb was also measured. The short latency and amplitude of waves in SEPs were measured. The SEP results were divided into 3 groups: flat (no evoked potential), abnormal (evoked but delayed in latency), and normal (clear waveform with normal latency).

RESULTS

The normal response of cortical SEP increased after injection. The SEPs exhibited more frequent improvement in the limbs, with greater improvement of spasticity in grade (>1.0 grade) and in patients of younger age (<3y) after injection (P<.05).

CONCLUSION

The observed improvement of cortical SEPs with associated reduction of spasticity that occurred after the botulinum toxin type A injection indicates that spasticity itself can be considered a factor affecting cortical SEPs.

Abnormalities of somatosensory evoked potentials in konzo--an upper motor neuron disorder

OBJECTIVE

To determine whether the somatosensory pathways are involved or not in konzo.

METHODS

In 1998, 21 konzo subjects (15 females and 6 males; mean age 21 years) underwent a SEP study with a two-channel-equipment (Medtronic Keypoint, Denmark) whereas in 2000, 15 subjects (7 females and 8 males; mean age 21 years) participated in a study with a 4-channel-equipment.

RESULTS

Most subjects (19/21 in 1998 and 12/15 in 2000) showed normal median SEPs. The remainders had no median cortical responses. All 21 subjects in 1998 and 9 out of 15 in 2000 showed abnormalities of tibial SEPs mainly consisting of absence of cortical responses, prolonged cortical latencies, and central sensory delay to the lumbar spine. Most subjects showed normal absolute latencies both at peripheral and spinal levels. The SEP findings did not correlate with the severity, neither the duration of konzo, nor the experience or not of sensory symptoms at the onset of the disease.

CONCLUSION

Our findings are not specific of konzo. However, they suggest involvement of intracranial somatosensory pathways and point to similarities with other motor neuron diseases.

Progression of abnormalities in adrenomyeloneuropathy and neurologically asymptomatic X-linked adrenoleukodystrophy despite treatment with "Lorenzo's oil"

OBJECTIVES

X-linked adrenoleukodystrophy (X-ALD) is an inherited disorder of peroxisomal fatty acid oxidation, biochemically characterised by the accumulation of saturated very long chain fatty acids (VLCFAs), particularly hexacosanoic acid (C26:0). Dietary treatment with a 4:1 mixture of glyceroltrioleate and glyceroltrierucate ("Lorenzo's oil") normalises plasma VLCFA concentrations, but neither ameliorates nor arrests the rapid progression of neurological symptoms in the cerebral variants of X-ALD. The efficacy of "Lorenzo's oil" in the milder phenotypes of X-ALD was assessed, as this has been much less investigated.

METHODS

Twenty two patients who were treated with "Lorenzo's oil" for at least 12 months for a median period of 2.5 (range 1.0-6.0) years were studied. Two had asymptomatic ALD, four the "Addison only" variant, 13 adrenomyeloneuropathy (AMN), and three were symptomatic female carriers.

RESULTS

The plasma C26:0 concentration normalised or near normalised in 19 patients (86%), in the three others it decreased significantly. Nevertheless, disability as measured with the extended disability status scale score increased mildly (0.5 (95% confidence interval (95% CI) 0.25-1.0)) in the 16 patients with neurological symptoms. Furthermore, one "Addison only" patient and one patient with AMN developed cerebral demyelination, and another "Addison only" patient developed AMN. Adrenocortical insufficiency evolved in one patient with AMN, and hypogonadism in one patient with asymptomatic ALD and two patients with AMN. Nerve conduction, evoked potential studies (SEP, BAEP, VEP), and abnormalities on cerebral MRI did not improve. On the other hand, side effects were often noted-namely, mild increases in liver enzymes (55%), thrombocytopenia (55%), gastrointestinal complaints (14%), and gingivitis (14%). We also found a mild decrease in haemoglobin concentration and leucocyte count.

CONCLUSIONS

The data suggest that treatment with "Lorenzo's oil" neither improved neurological or endocrine function nor arrested progression of the disease. Furthermore, the oil often induced adverse effects. Therefore, it is advocated that "Lorenzo's oil" should not be prescribed routinely to patients with X-ALD who already have neurological deficits.

Predicting neurologic recovery in traumatic cervical spinal cord injury

OBJECTIVE

Traumatic spinal cord injury (SCI) affects 8,000 to 10,000 individuals per year in the United States. One of the most difficult tasks confronting the clinician is the discussion of neurologic recovery and prognosis with the patient and/or family. Our objective is to provide a guide for practitioners to accurately predict neurologic outcome in acute traumatic cervical SCI (tetraplegia).

DATA SOURCE

Published reports obtained through MEDLINE search, texts, and studies presented at national conferences.

STUDY SELECTION

Peer reviewed studies, in English language, that discussed prognosis after traumatic SCI.

CONCLUSION

A comprehensive physical examination of the acute SCI patient is essential in determining the initial level and classification of the injury and is the most accurate method to predict neurologic recovery. Other diagnostic tests, including somatosensory evoked potentials, magnetic resonance imaging, and transcranial magnetic stimulation, may be helpful in further determining outcome when used in association with the clinical examination. The understanding of neurologic recovery should help predict ultimate functional capability and potential needs.

Ambulatory capacity in spinal cord injury: significance of somatosensory evoked potentials and ASIA protocol in predicting outcome

OBJECTIVE

Prediction of outcome of ambulatory capacity in patients with acute spinal cord injury (SCI) by the American Spinal Injury Association (ASIA) protocol and somatosensory evoked potentials (SSEP).

DESIGN

Correlational study on a prospective cohort.

SETTING

Spinal cord injury center, university hospital.

PATIENTS

Consecutively sampled, 70 acute and 34 chronic SCI patients.

MAIN OUTCOME MEASURES

(1) ASIA motor and sensory scores; (2) tibial and pudendal SSEP graded in 5 categories, from normal to absent; (3) ambulatory capacity rated as no, therapeutic, functional, or full. The outcome of the ambulatory capacity was assessed after discharge from the rehabilitation program, at least 6 months after trauma.

RESULTS

In acute SCI both the initial ASIA scores and the SSEP recordings are related (p < .001) to the outcome of ambulatory capacity. In acute tetraplegia the pudendal SSEP (spearman corr. coeff. .92; p < .001) and in acute paraplegia the ASIA motor score (spearman corr. coeff. .90; p < .001) were best related to the outcome of ambulatory capacity. In the early stage of acute SCI, ASIA scores and SSEP recordings can help to assess the outcome of ambulatory capacity and, therefore, can contribute to the selection of the appropriate therapeutic approaches during the rehabilitation program. In patients with acute SCI the ASIA motor score significantly increased (p < .05) in the 6 months after trauma, whereas the ASIA sensory scores and SSEP recordings did not change significantly during this same period.

CONCLUSION

ASIA scores and SSEP are related to the outcome of ambulatory capacity in patients with acute spinal cord injury; in noncomprehensive or uncooperative patients the SSEP are of supplemental value to the clinical examination. Therefore, the combination of clinical and electrophysiological examinations can be of additional diagnostic value in the assessment of acute spinal cord injury.