Stimulation parameters for motor evoked potentials during intraoperative spinal cord monitoring. A systematic review

OBJECTIVE

The aim of this systematic review was to find the optimal stimulation parameters for muscle recorded transcranial electrical stimulation motor evoked potential (mTc-MEP) and D-wave monitoring during spinal cord monitoring.

METHODS

A PRISMA systematic search in Medline and EMBASE and a QUADAS-2 quality evaluation was performed to identify studies that compared stimulation parameters consisting of stimulation location, number of pulses, pulse duration, interstimulus interval, double train (DTS) or recurrent train stimulation (RTS) and intertrain interval (ITI) for performing mTc-MEP and D-wave monitoring. Only studies that used total intravenous anaesthesia (TIVA) were included.

RESULTS

Ten studies that compared stimulation parameters for performing mTc-MEP monitoring (stimulation location n = 4, number of pulses n = 2, pulse duration n = 1, interstimulus interval n = 4, DTS n = 1, RTS n = 2, ITI n = 2) were included. No studies compared stimulation parameters (stimulation location and pulse duration) for performing D-wave monitoring.

CONCLUSIONS

Few studies examined the optimal stimulation parameters for monitoring mTc-MEPs and no studies were included for D-wave monitoring. There is a need for prospective research to investigate the optimal stimulation parameters for mTc-MEP with the use of TIVA and D-wave monitoring.

SIGNIFICANCE

For mTc-MEP monitoring, a table is provided in which the recommended stimulation parameters are stated.

Feasibility and optimal choice of stimulation parameters for supramaximal stimulation of motor evoked potentials

PURPOSE

The aim was to investigate the feasibility and optimal stimulation parameters for supramaximal stimulation of muscle recorded transcranial electrical stimulation motor evoked potentials (mTc-MEP).

METHODS

Forty-seven consecutive patients that underwent scoliosis surgery were included. First, the feasibility of supramaximal stimulation was assessed for two settings (setting 1: pulse duration 0.075ms, interstimulus interval (ISI) 1.5ms; setting 2: pulse duration 0.300ms, ISI 3ms). Thereafter, three mTc-MEP parameters were considered for both settings; (1) elicitability, (2) amplitude, and (3) if supramaximal stimulation was achieved with ≥ 20 V below maximum output. Finally, ISIs (1ms-4ms) were optimized for setting 1.

RESULTS

Nine patients (19.15%) were excluded. Of the remaining patients, supramaximal stimulation was achieved in all patients for setting 1, and in 26 (68.42%) for setting 2. In one patient, mTc-MEPs were elicitable in more muscles for setting (1) Amplitudes were not significantly different. Stimulation voltage could be increased ≥ 20 V in all 38 patients for setting 1 and in 10 (38.46%) for setting (2) Optimal ISI's differed widely.

CONCLUSION

We recommend using setting 1 when monitoring mTc-MEPs with supramaximal stimulation, after which an individualized ISI optimization can be performed. Moreover, when using supramaximal stimulation, short ISI's (i.e. 1ms or 1.5ms) can be the optimal ISI for obtaining the highest mTc-MEP amplitude.

POS1395 NEUROFILAMENT LIGHT CHAIN, AN EARLY BIOMARKER FOR POLYNEUROPATHY IN HEREDITARY ATTR AMYLOIDOSIS

Background

Serum neurofilament light chain (sNfL) is a sensitive marker for polyneuropathy (PNP) in hereditary transthyretin-related (ATTRv) amyloidosis patients and correlates with the severity of polyneuropathy [1-4]. We hypothesized that sNfL may diagnose neuronal damage in patients with hATTR amyloidosis before the onset of symptoms and before PNP can be detected by electromyography (EMG) examination.

Objectives

To establish the course of sNfL in three different groups: 1. persistently asymptomatic variant carriers (with and without detected amyloid), 2. ATTRv amyloidosis patients with PNP on treatment, 3. variant carriers who develop PNP.

Methods

sNfL levels were assessed longitudinally in asymptomatic variant carriers (with and without detectable amyloid), ATTRv amyloidosis patients with PNP on treatment (either a transthyretin (TTR) stabilizer or patisiran, an RNA interference therapeutic), and variant carriers who developed PNP. PNP was established by EMG examination. The single-molecule array (Simoa) assay was used to assess sNfL levels.

Results

sNfL levels significantly increased over 1 year in 20 persistently asymptomatic carriers (p<0.001), with the strongest increase in variant carriers (n=8) with detectable amyloid in the subcutaneous abdominal fat tissue. In 21 symptomatic ATTRv amyloidosis patient with PNP on treatment with a TTR stabilizer, sNfL levels remained stable over 1 year. In 24 patients treated with patisiran, sNfL levels significantly decreased after 1 year of treatment (p=0.01). In 8 out of 9 variant carriers who developed PNP a rise in the sNfL level could be observed before the onset of symptoms and establishment of PNP by EMG examination (Figure 1).

Figure 1.

Conclusion

sNfL is a marker for early neuronal damage since a rise in sNfL level occurs before abnormalities can be detected by EMG examination. Our data support the use of sNfL in monitoring disease progression, screening asymptomatic variant carriers and monitoring of treatment effect.

References

[1]Louwsma et al. Amyloid 2021;28(1):50-55

[2]Maia et al. Amyloid 2020;27(2):97-102

[3]Kapoor et al. J Perpher nerv syst 2019;24:314-319

[4]Ticau et al. Neurology 2021;96:e412-e422

Disclosure of Interests

Anne Floor Brunger: None declared, Milou Berends: None declared, Johan Bijzet: None declared, Paul van der Zwaag: None declared, Bart-Jan Kroesen: None declared, Charlotte Teunissen: None declared, Sjors in ‘t Veld: None declared, Gea Drost: None declared, Fiete Lange: None declared, Reinold Gans: None declared, Bouke Hazenberg Consultant of: Alnylam and Pfizer, Hans L.A. Nienhuis Consultant of: Alnylam and Pfizer

The influence of depth of anesthesia and blood pressure on muscle recorded motor evoked potentials in spinal surgery. A prospective observational study protocol

For high-risk spinal surgeries, intraoperative neurophysiological monitoring (IONM) is used to detect and prevent intraoperative neurological injury. The motor tracts are monitored by recording and analyzing muscle transcranial electrical stimulation motor evoked potentials (mTc-MEPs). A mTc-MEP amplitude decrease of 50–80% is the most common warning criterion for possible neurological injury. However, these warning criteria often result in false positive warnings. False positives may be caused by inadequate depth of anesthesia and blood pressure on mTc-MEP amplitudes. The aim of this paper is to validate the study protocol in which the goal is to investigate the effects of depth of anesthesia (part 1) and blood pressure (part 2) on mTc-MEPs. Per part, 25 patients will be included. In order to investigate the effects of depth of anesthesia, a processed electroencephalogram (pEEG) monitor will be used. At pEEG values of 30, 40 and 50, mTc-MEP measurements will be performed. To examine the effect of blood pressure on mTc-MEPs the mean arterial pressure will be elevated from 60 to 100 mmHg during which mTc-MEP measurements will be performed. We hypothesize that by understanding the effects of depth of anesthesia and blood pressure on mTc-MEPs, the mTc-MEP monitoring can be interpreted more reliably. This may contribute to fewer false positive warnings. By performing this study after induction and prior to incision, this protocol provides a unique opportunity to study the effects of depths of anesthesia and blood pressure on mTc-MEPs alone with as little confounders as possible.

Trial registration number NL7772.

Long-term evaluation of intraoperative neurophysiological monitoring-assisted tethered cord surgery

PURPOSE

Patients with tethered spinal cord have been investigated for short-term effects after tethered spinal cord surgery in the past. However, little is known about the long-term effects in this patient group. In this retrospective, longitudinal, observational study, a patient sample of a previous report of 65 patients was reassessed to observe the long-term effects of intraoperative neurophysiological monitoring-assisted tethered cord surgery.

METHODS

With the use of patient charts and a survey, patients were scored on four domains: (1) neurological deficits, (2) urological deficits, (3) pain symptoms, and (4) orthopedic deficits. Measurements were performed at four moments in time: (1) preoperatively, (2) postoperatively, (3) follow-up 1 (4.6 years), and (4) follow-up 2 (11.2 years). Besides this, a subgroup analysis and a quality of life questionnaire were performed.

RESULTS

When observing the symptom domains in the long-term, the pain domain appeared to improve most postoperatively after which it remained stable over time. The neurological and urological domains showed a stable, slightly decreasing trend in the long-term follow-up. The orthopedic domain showed a significant increase of the number of patients with scoliosis during the long-term follow-up.

CONCLUSIONS

Lasting effects of stability in the neurological, urological, and pain domains were observed. Close monitoring during follow-up might contribute to early recognition of progressive scoliosis, in spite of detethering, in a risk group defined by females who underwent tethered cord surgery at or under the age of 12 years old with either lipomyelomeningocele, split cord malformation, or myelomeningocele. Detethering does not appear to protect these patients against progressive scoliosis.

Mutations in RYR1 are a common cause of exertional myalgia and rhabdomyolysis

Mutations in the skeletal muscle ryanodine receptor (RYR1) gene are a common cause of neuromuscular disease, ranging from various congenital myopathies to the malignant hyperthermia (MH) susceptibility trait without associated weakness. We sequenced RYR1 in 39 unrelated families with rhabdomyolysis and/or exertional myalgia, frequent presentations in the neuromuscular clinic that often remain unexplained despite extensive investigations. We identified 9 heterozygous RYR1 mutations/variants in 14 families, 5 of them (p.Lys1393Arg; p.Gly2434Arg; p.Thr4288_Ala4290dup; p.Ala4295Val; and p.Arg4737Gln) previously associated with MH. Index cases presented from 3 to 45 years with rhabdomyolysis, with or without exertional myalgia (n=12), or isolated exertional myalgia (n=2). Rhabdomyolysis was commonly triggered by exercise and heat and, less frequently, viral infections, alcohol and drugs. Most cases were normally strong and had no personal MH history. Inconsistent additional features included heat intolerance, and cold-induced muscle stiffness. Muscle biopsies showed mainly subtle changes. Familial RYR1 mutations were confirmed in relatives with similar or no symptoms. These findings suggest that RYR1 mutations may account for a substantial proportion of patients presenting with unexplained rhabdomyolysis and/or exertional myalgia. Associated clinico-pathological features may be subtle and require a high degree of suspicion. Additional family studies are paramount in order to identify potentially MH susceptible relatives.

Redefining the clinical phenotypes of non-dystrophic myotonic syndromes

OBJECTIVE

To redefine phenotypical characteristics for both chloride (ClCh) and sodium channelopathies (NaCh) in non-dystrophic myotonic syndromes (NDM).

METHODS

In a cross-sectional, nationwide study, standardised interviews and clinical bedside tests were performed in 62 genetically confirmed NDM patients, 32 ClCh and 30 NaCh.

RESULTS

Standardised interviews revealed that ClCh reported a higher frequency of muscle weakness (75 vs 36.7%; p<0.01), the warm-up phenomenon (100 vs 46.7%; p<0.001), and difficulties in standing up quickly (90.6 vs 50.0%; p<0.001), running (90.6% vs 66.7; p<0.05) and climbing stairs (90.6 vs 63.3%; p = 0.01). Patients with NaCh reported an earlier onset (4.4 vs 9.6 years; p<0.001), and higher frequencies of paradoxical (50.0 vs 0%; p<0.001) and painful myotonia (56.7 vs 28.1%; p<0.05). Standardised clinical bedside tests showed a higher incidence and longer relaxation times of myotonia in the leg muscles for ClCh (100 vs 60%; mean duration of chair tests 12.5 vs 6.3 s; p<0.001), and in eyelid muscles for NaCh (96.7 vs 46.9%; mean relaxation time of 19.2 vs 4.3 s; p<0.001). Transient paresis was only observed in ClCh (62.5%) and paradoxical myotonia only in NaCh (30.0%). Multivariate logistic regression analyses allowed clinical guidelines to be proposed for genetic testing.

CONCLUSION

This study redefined the phenotypical characteristics of NDM in both ClCh and NaCh. The clinical guidelines proposed may help clinicians working in outpatient clinics to perform a focused genetic analysis of either CLCN1 or SCN4A.

Health status in non-dystrophic myotonias: close relation with pain and fatigue

To determine self-reported health status in non-dystrophic myotonias (NDM) and its relationship to painful myotonia and fatigue. In a cross-sectional study, 32 NDM patients with chloride and 30 with sodium channelopathies, all off treatment, completed a standardised interview, the fatigue assessment scale (FAS), and the 36-item Short-Form Health Survey (SF-36). Beside formal assessment of pain, assessment of painful or painless myotonia was determined. The domain scores of the SF-36 were compared with Dutch community scores. Apart from the relationship among SF-36 scores and (1) painful myotonia and (2) fatigue, regression analyses in both NDM groups were conducted to determine the strongest determinants of the SF-36 domains general health perception, physical component (PCS) and mental component summary (MCS). All physically oriented SF-36 domains in both NDM groups (P ≤ 0.01) and social functioning in the patients with sodium channelopathies (P = 0.048) were substantially lower relative to the Dutch community scores. The patients with painful myotonia (41.9%) scored substantially (P < 0.05) lower on most SF-36 domains than the patients without painful myotonia (58.1%). Fatigued patients (53.2%) scored substantially lower (P ≤ 0.01) on all SF-36 domains than their non-fatigued counterparts (46.8%). The regression analysis showed that fatigue was the strongest predictor for the general-health perception and painful myotonia for the physical-component summary. None of the patients showed below-norm scores on the domain mental-component summary. The impact of NDM on the physical domains of patients’ health status is substantial, and particularly painful myotonia and fatigue tend to impede their physical functioning.

Trunk sway analysis to quantify the warm-up phenomenon in myotonia congenita patients

OBJECTIVE

Patients with autosomal recessive myotonia congenita display myotonia and transient paresis that diminish with repetitive muscle contractions (warm-up phenomenon). A new approach is presented to quantify this warm-up phenomenon under clinically relevant gait and balance tasks.

METHODS

Ten patients with DNA proven autosomal recessive myotonia congenita and 14 age-matched controls participated. Subjects performed six everyday gait and balance tasks. Balance control during these tasks was monitored using two angular velocity transducers that measured trunk movements in anterior-posterior (pitch) and medio-lateral (roll) directions at the level of the lumbar vertebral column. Tasks were performed under two conditions in randomised order: after a 10-minute seated rest period ("rested") and after having consecutively repeated the task five times ("warm-up"). Controls were also tested twice.

RESULTS

"Rested" patients showed the greatest abnormalities (increased sway in pitch and roll) for tandem walking and walking stairs. Balance impairment was also evident for all other tasks. After "warm-up," balance was markedly improved in patients, as reflected by decreased trunk sway (especially during tandem walking) and reduced task duration for all tasks. These results were not only evident at the group level but also clearly present in individual patients.

CONCLUSION

The results show that trunk sway analysis detects postural instability in myotonia congenita patients during everyday gait and balance tasks. Moreover, this technique provides a useful tool to quantify the warm-up phenomenon, suggesting a potential use as clinical endpoint in future clinical trials.

Thought ripples on muscle waves: recognition of rippling muscle disease

We report on a 16-year-old Dutch patient in whom rippling muscle disease (RMD) was diagnosed years after his mother had been falsely diagnosed with acid maltase deficiency. The autosomal dominant mode of inheritance of the neuromuscular symptoms in this family had led to a re-evaluation of the diagnosis of acid maltase deficiency. Physical examination revealed the three key features leading to the clinical diagnosis of RMD: rippling, mounding, and percussion-induced rapid muscle contraction. Mutation analysis revealed a novel heterozygous missense mutation in the caveolin-3 gene (c.79C > G; p.Arg27Gly) in both the index patient and his mother. This case report stresses the importance of adhering to the mode of inheritance in the diagnosis of neuromuscular disorders. It also indicates that typical RMD phenomena are not easily acknowledged among paediatricians or neurologists. We therefore present an overview of these clinical characteristics of rippling muscle disease RMD.

Drug treatment for myotonia

BACKGROUND

Abnormal delayed relaxation of skeletal muscles, known as myotonia, can cause disability in myotonic disorders. Sodium channel blockers, tricyclic antidepressive drugs, benzodiazepines, calcium-antagonists, taurine and prednisone may be of use in reducing myotonia.

OBJECTIVES

To consider the evidence from randomised controlled trials on the efficacy and tolerability of drug treatment in patients with clinical myotonia due to a myotonic disorder.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register (April 2004), MEDLINE (January 1966 to December 2003) and EMBASE (January 1980 to December 2003). Grey literature was handsearched and reference lists of identified studies and reviews were examined. Authors, disease experts and manufacturers of anti-myotonic drugs were contacted.

SELECTION CRITERIA

We considered all (quasi) randomised trials of participants with myotonia treated with any drug treatment versus no therapy, placebo or any other active drug treatment. The primary outcome measure was:reduced clinical myotonia using two categories: (1) no residual myotonia or improvement of myotonia or (2) No change or worsening of myotonia. Secondary outcome measures were:(1) clinical relaxation time; (2) electromyographic relaxation time; (3) stair test; (4) presence of percussion myotonia; and (5) proportion of adverse events.

DATA COLLECTION AND ANALYSIS

Two authors extracted the data independently onto standardised extraction forms and disagreements were resolved by discussion.

MAIN RESULTS

Nine randomised controlled trials were found comparing active drug treatment versus placebo or another active drug treatment in patients with myotonia due to a myotonic disorder. Included trials were double-blind or single-blind crossover studies involving a total of 137 patients of which 109 had myotonic dystrophy type 1 and 28 had myotonia congenita. The studies were of poor quality. Therefore, we were not able to analyse the results of all identified studies. Two small crossover studies without a washout period demonstrated a significant effect of imipramine and taurine in myotonic dystrophy. One small crossover study with a washout period demonstrated a significant effect of clomipramine in myotonic dystrophy. Meta-analysis was not possible.

AUTHORS' CONCLUSIONS

Due to insufficient good quality data and lack of randomised studies, it is impossible to determine whether drug treatment is safe and effective in the treatment of myotonia. Small single studies give an indication that clomipramine and imipramine have a short-term beneficial effect and that taurine has a long-term beneficial effect on myotonia. Larger, well-designed randomised controlled trials are needed to assess the efficacy and tolerability of drug treatment for myotonia.

[Case report: mast cell leukosis in a neonatal calf]

Multicentric mast cell tumours in a newborn Fleckvieh-calf are described. The calf showed clearly pronounced lesions over the whole body. The lesions were multiple raised, cutaneous, greyisch-red and partially ulcerated. It died three hours after birth. Pathohistological examinations resulted in multiple mast cell tumours within the dermis. In addition multifocal to diffuse mast cell aggregations were observed in several internal organs including the lymph nodes and the bone marrow. No evidence for the presence of bovine leukemia virus was found by both investigating a lymph node homogenate of the calf and a blood sample of the mother cow. In this paper the pathomorphology of this rare disease is described, a possible cause is discussed and a short review of the available literature is presented.

[The spectrum of hereditary skeletal-muscle channelopathies]

Channelopathies are a heterogeneous group of genetic diseases in which a defective ion channel is responsible for the symptoms. They manifest as diseases of the heart, brain or skeletal muscle. Hereditary skeletal-muscle channelopathies are characterised by myotonia, periodic paralysis or a combination of both and can be categorised as chloride, sodium and calcium channelopathies. When there is myotonia, the skeletal-muscle membrane is overexcited. In cases of periodic paralysis, the skeletal-muscle membrane is inactive. It is difficult to classify hereditary muscle channelopathies on the basis of clinical criteria only. A more reliable diagnosis is made using DNA analysis. Scientific research should focus on genotype-phenotype relationships.

Pyridostigmine in postpolio syndrome: no decline in fatigue and limited functional improvement

OBJECTIVES

To investigate the effect of pyridostigmine on fatigue, physical performance, and muscle function in subjects with postpoliomyelitis syndrome.

METHODS

67 subjects with increased fatigue and new weakness in one quadriceps muscle showing neuromuscular transmission defects, were included in a randomised, double blind, placebo controlled trial of 60 mg pyridostigmine four times a day for 14 weeks. Primary outcome was fatigue (on the "energy" category of the Nottingham health profile). Secondary outcomes included two minute walking distance and quadriceps strength and jitter. Motor unit size of the quadriceps was studied as a potential effect modifier. The primary data analysis compared the changes from baseline in the outcomes in the last week of treatment between groups.

RESULTS

31 subjects treated with pyridostigmine and 31 subjects treated with placebo completed the trial. No significant effect of pyridostigmine was found on fatigue. The walking distance improved more in the pyridostigmine group than in the placebo group (by 7.2 m (6.0%); p<0.01). Subgroup analysis showed that a significant improvement in walking performance was only found in subjects with normal sized motor units. Quadriceps strength improved more in the pyridostigmine group than in the placebo group (by 6.7 Nm (7.2%); p = 0.15). No effect of pyridostigmine was found on jitter.

CONCLUSIONS

Pyridostigmine in the prescribed dose did not reduce fatigue in subjects with postpoliomyelitis syndrome. However, it may have a limited beneficial effect on physical performance, especially in subjects with neuromuscular transmission defects in normal sized motor units.

Selective spatial information from surface EMG after temporal filtering: the application to interference EMG using cross-covariance analysis

OBJECTIVE

An increased spatial resolution in multichannel surface EMG recordings would provide new possibilities for the investigation of intermuscular and intramuscular coordination. A known analytical solution for volume conduction allows the conclusion that a high pass filtered surface electromyography (SEMG) signal contains information from a smaller environment near the recording electrode and therefore provides a higher spatial resolution.

METHODS

The present paper concerns experiments on 9 subjects to measure, from the human biceps brachii muscle during static isometric contraction, using multichannel surface EMG. Cross-correlation functions between bipolar SEMG channels were calculated and high pass filtered.

RESULTS

The correlation peaks showed the signs of propagating action potentials. The spatial width in the direction perpendicular to the muscle fibres decreased with increasing cut-off frequency. There exists an optimal cut-off frequency, which provides the best spatial resolution. It correlates with the thickness of the subcutaneous fat layer which causes a minimum depth of the active muscle fibres measured.

CONCLUSIONS

High pass filtered cross-covariance functions of bipolar SEMG channels have an increased spatial resolution perpendicular to the muscle fibre direction and the frequency content of the signals can potentially give an indication of the depth of the active muscle fibres.

Propagation disturbance of motor unit action potentials during transient paresis in generalized myotonia: a high-density surface EMG study

Patients with autosomal recessive generalized myotonia, or Becker's disease, often suffer from a peculiar transient paresis. As yet, the relationship between this transient paresis and the defect in the gene encoding for a voltage gated Cl- channel protein in the muscle membrane of these patients is unclear. In order to gain a better understanding of the electrophysiological properties of the muscle fibre membrane in these generalized myotonia patients, we have studied transient paresis with a novel high-density surface EMG (sEMG) technique. We conclude that the transient paresis is explained by a deteriorating muscle membrane function, ending in conduction block and paresis. Multi-channel sEMG during the period of force decline in transient paresis shows a decrease in peak-peak amplitude of the motor unit action potentials from endplate towards tendon. This disturbance increases with time and place, indicating a deteriorating membrane function, and ends in a complete blocking of propagation within seconds. Spatiotemporally, this leads to a V-shaped sEMG pattern. In a more general sense, this contribution shows how spatiotemporal information, available through non-invasive high-density sEMG, may provide novel insights into electrophysiological aspects of membrane dysfunction.

Recent progress in the diagnostic use of surface EMG for neurological diseases

The different techniques to measure and analyze surface EMG are summarized with an emphasis on the clinician's point of view. The application of surface EMG in neurological disease is hampered by many inherent problems, especially the difficulties in extracting features of single motor units. However, the evolution of surface EMG from single bipolar recordings via a linear array of multiple electrodes to densely packed, multi-channel electrode arrays could in principle solve this problem. The added value of using multiple channels (up to 128) with an interelectrode distance of a few millimetres to obtain more spatial information is emphasized. At least for some muscles it is now possible to extract information from the surface EMG, conventionally thought to belong to the domain of needle EMG (for example the "electrical size" of motor units). The use of analysis techniques such as the estimation of muscle fiber conduction velocity has already proven to be of diagnostic value in several myopathies characterized by a disturbed membrane function and in metabolic myopathies with abnormal fatigue profiles. Future research should be directed at the development of analysis techniques enabling the extraction of more relevant motor unit variables from surface EMG signals.

Cerebellar involvement as a rare complication of pneumococcal meningitis

A 4-year old girl with meningitis, caused by streptococcus pneumoniae, developed a subcoma with respiratory insufficiency, followed by a severe cerebellar syndrome. Cerebellar involvement after regaining consciousness consisted of a symmetrical ataxia and mutism. This mutism changed into dysarthria and finally into normal speech. Magnetic resonance imaging revealed lesions in both cerebellar hemispheres, suggesting cerebellitis. She recovered with prompt antibiotic treatment.

Induction and characterization of monoclonal anti-idiotypic antibodies reactive with idiotopes of canine parvovirus neutralizing monoclonal antibodies

Monoclonal anti-idiotypic (anti-Id) antibodies (Ab2) were generated against idiotypes (Id) of canine parvovirus (CPV) specific monoclonal antibodies (MoAbs). The binding of most of these anti-Id antibodies to their corresponding Id could be inhibited by antigen, thus classifying these anti-Id antibodies as Ab2 gamma or Ab2 beta. By inhibiting experiments it was shown that these anti-Id antibodies did not recognize interspecies cross-reactive idiotopes, but recognized private idiotopes, uniquely associated with the Id of the anti-CPV MoAb used for immunization. This classifies these anti-Id antibodies as non-internal image Ab2 gamma. The potential use of these non-internal image anti-Id antibodies for the induction of antiviral antibodies in the CPV system is discussed.