Subgroup comparison according to clinical phenotype and serostatus in autoimmune encephalitis: a multicenter retrospective study.

BACKGROUND AND PURPOSE: Autoimmune encephalitides (AE) include a spectrum of neurological disorders whose diagnosis revolves around the detection of neuronal antibodies (Abs). Consensus-based diagnostic criteria (AE-DC) allow clinic-serological subgrouping of AE, with unclear prognostic implications. The impact of AE-DC on patients' management was studied, focusing on the subgroup of Ab-negative-AE. METHODS: This was a retrospective multicenter study on patients fulfilling AE-DC. All patients underwent Ab testing with commercial cell-based assays (CBAs) and, when available, in-house assays (immunohistochemistry, live/fixed CBAs, neuronal cultures) that contributed to defining final categories. Patients were classified as Ab-positive-AE [N-methyl-d-aspartate-receptor encephalitis (NMDAR-E), Ab-positive limbic encephalitis (LE), definite-AE] or Ab-negative-AE (Ab-negative-LE, probable-AE, possible-AE). RESULTS: Commercial CBAs detected neuronal Abs in 70/118 (59.3%) patients. Testing 37/48 Ab-negative cases, in-house assays identified Abs in 11 patients (29.7%). A hundred and eighteen patients fulfilled the AE-DC, 81 (68.6%) with Ab-positive-AE (Ab-positive-LE, 40; NMDAR-E, 32; definite-AE, nine) and 37 (31.4%) with Ab-negative-AE (Ab-negative-LE, 17; probable/possible-AE, 20). Clinical phenotypes were similar in Ab-positive-LE versus Ab-negative-LE. Twenty-four/118 (20.3%) patients had tumors, and 19/118 (16.1%) relapsed, regardless of being Ab-positive or Ab-negative. Ab-positive-AE patients were treated earlier than Ab-negative-AE patients (P = 0.045), responded more frequently to treatments (92.3% vs. 65.6%, P < 0.001) and received second-line therapies more often (33.3% vs. 10.8%, P = 0.01). Delays in first-line therapy initiation were associated with poor response (P = 0.022; odds ratio 1.02; confidence interval 1.00-1.04). CONCLUSIONS: In-house diagnostics improved Ab detection allowing better patient management but was available in a patient subgroup only, implying possible Ab-positive-AE underestimation. Notwithstanding this limitation, our findings suggest that Ab-negative-AE and Ab-positive-AE patients share similar oncological profiles, warranting appropriate tumor screening. Ab-negative-AE patients risk worse responses due to delayed and less aggressive treatments.

Stroke-like events after brain radiotherapy: a large series with long-term follow-up.

BACKGROUND AND PURPOSE: Patients with a history of brain radiotherapy can experience acute stroke-like syndromes related to the delayed effects of brain radiation, including stroke-like migraine attacks after radiation therapy syndrome, peri-ictal pseudoprogression and acute late-onset encephalopathy after radiation therapy syndrome. The aim of this study was to collect evidence on the long-term outcome and treatment of these conditions, whose knowledge is undermined by their rarity and fragmented description. METHODS: Cases were collected, both prospectively and retrospectively, amongst six neuro-oncology departments. Inclusion criteria were as follows: (i) history of brain radiotherapy (completed at least 6 months before the acute episode); (ii) new onset of acute/subacute neurological symptoms; (iii) exclusion of all etiologies unrelated to brain irradiation. A review of current literature on stroke-like syndromes was performed to corroborate our findings. RESULTS: Thirty-two patients with acute neurological conditions attributed to the delayed effects of radiation were identified, including 26 patients with stroke-like syndromes. Patients with stroke-like syndromes commonly presented with a mosaic of symptoms, including focal deficits (77%), encephalopathy (50%), seizures (35%) and headache (35%). Seventy-three percent of them had acute consistent magnetic resonance imaging alterations. Treatment included high-dose steroids in 65% of cases. Twenty-two patients recovered completely (85%). Sixteen patients (62%) experienced relapses (median follow-up 3.5 years). A literature review identified 87 additional stroke-like cases with similar characteristics. CONCLUSIONS: Stroke-like events related to brain irradiation may be associated with permanent sequelae. Steroids are often administered on empirical grounds, as they are thought to accelerate recovery. Relapses are common, highlighting the need to elaborate adequate prevention strategies.

Hub-and-spoke stroke network in the Veneto region: a retrospective study investigating the effectiveness of the stroke pathway and trends over time.

After recognizing the pivotal role played by stroke unit (SU) admission in reducing mortality and dependency in stroke patients, the need to organize and monitor stroke networks has become an increasingly essential aspect of stroke care. We conducted a retrospective study of stroke patients admitted to hospitals in the Veneto region from 2007 to 2015 in order to evaluate the effectiveness of the stroke pathway and trends over time. Between 2007 and 2015, 61,062 stroke patients were discharged from Veneto hospitals: they were more frequently female, females were older than males, and had higher intrahospital mortality and a lower probability of undergoing systemic thrombolysis. Patients admitted to facilities with a level 2 SU were twice as likely to undergo thrombolytic treatment compared to those admitted to facilities with a level 1 and had a lower intrahospital mortality rate. During the collection period, thrombolytic treatments increased in both level 1 and 2 SUs, as did the number of patients admitted to neurology wards and to facilities with an SU. Our study confirmed that thrombolytic treatment and admission to a facility with an SU are important determinants in improving stroke patient outcome. The increase in the proportion of both SU admissions and thrombolytic treatments demonstrates the effectiveness of the regional hub-and-spoke organization model, suggesting that implementation of highly specialized facilities is an efficient strategy in improving stroke care. The role of the observed sex bias in stroke treatment and outcome needs to be explored.

Prostate cancer, Hu antibodies and paraneoplastic neurological syndromes.

Prostate cancer is the most common cancer among American and European men. Nervous system affection caused by local tumor growth or osseous metastases are the main causes of neurological symptoms in prostate cancer patients. Prostate cancer is rarely reported in association with paraneoplastic neurological syndromes (PNS). We have, therefore, studied clinical and paraclinical findings of a series of patients with prostate cancer and PNS, and reviewed cases reported in the literature. Case histories of 14 patients with definite PNS from the PNS Euronetwork database and from the authors' databases were reviewed. A PubMed literature search identified 23 patients with prostate cancer and PNS. Thus, a total of 37 case histories were reviewed with respect to syndrome type, cancer evolution, paraclinical investigations, antibody status, treatment and outcome. The three most frequent isolated PNS were paraneoplastic cerebellar degeneration, paraneoplastic encephalomyelitis (PEM)/limbic encephalitis and subacute sensory neuronopathy (SSN). Onconeural antibodies were detected in 23 patients, in most cases the Hu antibody (17 patients, 74 % of all antibody-positive cases). Other well-characterized onconeural antibodies (Yo, CV2/CRMP5, amphiphysin, VGCC antibodies) were found in a minority. PNS was diagnosed prior to prostate cancer diagnosis in 50 % of the cases. The association of PNS with prostate cancer is quite infrequent, but clinically important. PNS often heralds prostate cancer diagnosis. Syndromes associated with Hu antibodies predominate. Another tumor more prone to associate with PNS should always be excluded.

Italian recommendations for Lambert-Eaton myasthenic syndrome (LEMS) management.

Lambert-Eaton myasthenic syndrome (LEMS) is a pre-synaptic disorder of the neuromuscular and autonomic transmission mediated by antibodies to voltage-gated calcium channels at the motor nerve terminal. LEMS is a quite rare and probably under-diagnosed disease: the onset may be slow and clinical signs are typically fluctuating, thus adding to the delay in diagnosis. LEMS weakness typically involves lower and upper limbs and the proximal muscles are predominantly affected. A significant proportion of patients also have dysfunction of the autonomic nervous system that may include dry mouth, constipation, blurred vision, impaired sweating, and orthostatic hypotension. LEMS recognition is based on clinical, electrophysiological and immunological criteria. Nearly 50-60% of patients with LEMS have an underlying tumour that, in almost all cases, is a small-cell lung cancer; the onset of neurological symptoms generally precedes tumour detection. A careful screening for the early detection of the possible associated cancer is a crucial step for optimal disease management. The Italian Working Group on Myasthenic Syndromes developed diagnostic and therapeutic algorithms that could serve in routine clinical practice as tools for a patient-tailored approach.

Seronegative paraneoplastic cerebellar degeneration: the PNS Euronetwork experience.

BACKGROUND AND PURPOSE: To describe the characteristics of patients presenting a paraneoplastic cerebellar degeneration without classical onconeural antibodies (seronegative PCD). METHODS: Thirty-nine seronegative PCD patients from the Paraneoplastic Neurological Syndrome Euronetwork were retrospectively analyzed and compared with 180 patients with PCD associated with classical onconeural antibodies (seropositive PCD). RESULTS: No patient had anti-CASPR2 or anti-mGluR1 antibodies. No significant difference between the clinical characteristics of seronegative and seropositive PCD patients was observed. Yet the frequency of associated tumors was different. Lymphoma was more frequent in seronegative than in seropositive women (24% vs. 2%, P = 0.002) whilst gynecological cancer were less frequent (38% vs. 74%, P = 0.002). In comparison with seropositive men, seronegative men more frequently had a non-small-cell lung cancer (27% vs. 6%, P = 0.08) or a genitourinary cancer (22% vs. 0%, P = 0.04) but less frequently a small-cell lung cancer (23% vs. 74%, P = 0.002). Seronegative and seropositive PCD patients with similar tumors had a similar overall survival. CONCLUSION: The clinical characteristics of seronegative and seropositive PCD are similar but the spectrum of associated tumors is different. The immunological scenario of seronegative PCD seems to be different from that of limbic encephalitis with only few patients harboring anti-neuropile antibodies.

Nutritional intervention for amyotrophic lateral sclerosis.

AIM: The aim of the study was to assess the consequences of early and systematic nutritional intervention on the clinical conditions of amyotrophic lateral sclerosis (ALS) patients and on the opportunity to maintain a good nutritional status for as long as possible. METHODS: Thirty-three subjects with ALS. Protocol Group: 12 subjects (9 M and 3 F) monitored according to a precise nutritional intervention protocol. CONTROL GROUP: 21 subjects (10 M and 11 F) monitored before applying the protocol. RESULTS: Data recorded at the time of initial assessment were compared and expressed as the mean ± standard deviation for the Protocol Group vs. the CONTROL GROUP: BMI (kg/m2) 23.6 ± 4.1 vs. 21.6 ± 3.5; weight loss as a percentage of usual weight 6.6 ± 7.9 vs. 16.3 ± 8.8 (P=0.003). At six months: weight loss as a percentage of usual weight 4.9 ± 6.2 vs. 16.9 ± 10.2 (P=0.002). At 12 months: weight loss as a percentage of usual weight 7.3 ± 7.1 vs. 17.5 ± 11.1 (P=0.03). At the first follow-up visit, fewer patients in the Protocol Group were receiving enteral nutrition (25%) than patients in the CONTROL GROUP (60%). At six-month follow-up visit: 30% vs. 68%. Standard enteral nutrition formulas were used. One year after initial assessment, the mortality rate was 17% for the Protocol Group, whereas it was 24% at six months and 33% after one year for the CONTROL GROUP. CONCLUSION: If patients are treated before any significant weight loss occurs, early and specific nutritional intervention allows good nutritional status to be maintained for a longer period; if artificial nutrition is required, standard diets are able to ensure adequate clinical results.

West Nile virus transmission through organ transplantation in north-eastern Italy: a case report and implications for pre-procurement screening.

PURPOSE: West Nile virus (WNV) transmission through organ transplantation occurs rarely and screening of organ donors for WNV infection remains controversial. This report describes the case of WNV encephalitis in a kidney recipient and the case of asymptomatic WNV infection in the organ donor, both observed at Treviso Hospital, northeastern Italy. After briefly reviewing the literature, we discuss the implications for WNV screening. METHODS: We reviewed medical, laboratory and epidemiological records at our hospital, and the literature concerning cases of organ-transmitted WNV infections and WNV screening of organ donors in Italy and worldwide. RESULTS: The kidney recipient was the first confirmed case of WNV infection notified in northeastern Italy in 2011, and the first case of WNV infection in a cluster of four transplant recipients who acquired the infection from a common organ donor. The organ donor, whose WNV infection was only retrospectively diagnosed by IgM detection, represents the index case of a WNV outbreak in the Treviso Province. Screening of her blood prior to organ recovery did not show detectable levels of WNV nucleic acid with the use of quantitative real-time polymerase chain reaction. CONCLUSIONS: This report emphasizes that transplant-acquired WNV neuroinvasive disease can be particularly severe. We suggest that pre-procurement screening of organ donors by testing blood with both WNV IgM capture ELISA and a sensitive nucleic acid testing should be adopted during the transmission season in the present Italian epidemiological setting.

Spectrum of paraneoplastic disease associated with lymphoma.

OBJECTIVE: To define the frequency and clinical and immunologic characteristics of patients affected by paraneoplastic neurologic syndromes (PNS) and lymphoma. METHODS: Patients fulfilling the criteria for PNS associated with lymphoma collected from the European Commission-funded PNS Euronetwork group database were analyzed. RESULTS: Fifty-three patients with Hodgkin lymphoma (HL) (24 patients, mean age 51, range 16-84) or non-Hodgkin lymphoma (NHL) (29 patients, mean age 64, range 31-82) and PNS were analyzed. The most commonly associated PNS was paraneoplastic cerebellar degeneration, present in 21 cases, with a higher prevalence in HL (16/24 cases). Peripheral nervous system (mainly demyelinating polyradiculopathies) and motor neuron involvement were more common in NHL. Onconeural antibodies were more frequent in patients with paraneoplastic cerebellar degeneration, most commonly against the Tr antigen. Fifty percent of the patients with PNS and HL responded to chemotherapy, whereas neurologic improvement was less frequent (24%) in patients with PNS and NHL. In both groups, the survival rate was good. Overall, 10 out of 53 patients eventually died, with only 2 patients (1 with HL, 1 with NHL) dying from PNS. CONCLUSIONS: PNS in patients with lymphoma are relatively rare. Paraneoplastic cerebellar degeneration, mainly associated with anti-Tr antibodies, is more prevalent in HL and NHL, followed in our study by motor neuron disease in patients with NHL. Involvement of the peripheral nervous system is heterogeneous, with a prevalence of polyradiculoneuritis in patients with NHL.

Screening for tumours in paraneoplastic syndromes: report of an EFNS task force.

BACKGROUND: paraneoplastic neurological syndromes (PNS) almost invariably predate detection of the malignancy. Screening for tumours is important in PNS as the tumour directly affects prognosis and treatment and should be performed as soon as possible. OBJECTIVES: an overview of the screening of tumours related to classical PNS is given. Small cell lung cancer, thymoma, breast cancer, ovarian carcinoma and teratoma and testicular tumours are described in relation to paraneoplastic limbic encephalitis, subacute sensory neuronopathy, subacute autonomic neuropathy, paraneoplastic cerebellar degeneration, paraneoplastic opsoclonus-myoclonus, Lambert-Eaton myasthenic syndrome (LEMS), myasthenia gravis and paraneoplastic peripheral nerve hyperexcitability. METHODS: many studies with class IV evidence were available; one study reached level III evidence. No evidence-based recommendations grade A-C were possible, but good practice points were agreed by consensus. RECOMMENDATIONS: the nature of antibody, and to a lesser extent the clinical syndrome, determines the risk and type of an underlying malignancy. For screening of the thoracic region, a CT-thorax is recommended, which if negative is followed by fluorodeoxyglucose-positron emission tomography (FDG-PET). Breast cancer is screened for by mammography, followed by MRI. For the pelvic region, ultrasound (US) is the investigation of first choice followed by CT. Dermatomyositis patients should have CT-thorax/abdomen, US of the pelvic region and mammography in women, US of testes in men under 50 years and colonoscopy in men and women over 50. If primary screening is negative, repeat screening after 3-6 months and screen every 6 months up till 4 years. In LEMS, screening for 2 years is sufficient. In syndromes where only a subgroup of patients have a malignancy, tumour markers have additional value to predict a probable malignancy.

Diagnostic accuracy of different immunological methods for the detection of antineuronal antibodies in paraneoplastic neurological syndromes.

The aim of this work was to evaluate the diagnostic accuracy of three different analytical methods for the detection of antineuronal antibodies and outline how they might be used to diagnose Paraneoplastic Neurological Syndromes (PNS) in a more effectively and rationally way. One hundred and four patients with neurological diseases were studied: 38 with paraneoplastic neurological disorder, 44 with other neurological diseases, and 22 with systemic autoimmune diseases and neurological disorders. 20 healthy subjects and 18 subjects with tumour without neurological disorders were also studied. Antineuronal antibodies were tested using three methods: Western blot (WB); Line-blot (LB); and indirect immunofluorescence (IIF) on primate cerebellum. The diagnostic sensitivity of the IIF, WB and LB methods was 28.9%, 26.3% and 36.8%, respectively, and their specificity was 95.2%, 97.1% and 98.1% respectively. The combined use of the three methods brought the sensitivity to 39.4%. The results of this study show that the methods used in clinical laboratories for the detection of antineuronal antibodies have good specificity. Among the three methods assessed, LB showed the highest diagnostic accuracy and also allowed for recognition of fine antibody specificities. According to these results we can suggest that LB should be used as the method of choice to search for paraneoplastic antibodies.

Anti-Hu-associated brainstem encephalitis.

OBJECTIVE: A series of patients with anti-Hu-associated brainstem encephalitis is reviewed to better define the clinical presentation and to improve its recognition. METHODS: Data were collected from 14 patients diagnosed by members of the Paraneoplastic Neurological Syndromes Euronetwork, and eight patients from the literature who presented with isolated brainstem encephalitis and had anti-Hu antibodies. RESULTS: The median age of the 22 patients was 64 years (range 42-83), and 50% were men. All patients developed a subacute neurological syndrome, in days or weeks. Brain MRI was always normal. Mild cerebrospinal fluid pleocytosis was reported in only two patients. The following syndromes were identified on admission: A medullary syndrome was seen in 11 (50%) patients. Seven of them presented with dysphagia, dysarthria and central hypoventilation. The other four in addition of bulbar symptoms, without central hypoventilation, presented pontine manifestations. Six (27%) patients developed a pontine syndrome with paresis of the VI or VII cranial nerves, nystagmus, usually vertical, and gait ataxia. There was a rapid downward progression to the medulla in all patients. Five (23%) patients presented a ponto-mesencephalic syndrome with uni- or bilateral palsy of the III and VI cranial nerves and gait ataxia, but rapidly progressed to complete gaze paresis and medullary dysfunction. CONCLUSIONS: The study confirms the predominant medullary involvement but also shows that half of the patients present with clinical features that indicate an upper, mainly pontine, dysfunction before downward progression.

Management of paraneoplastic neurological syndromes: report of an EFNS Task Force.

Paraneoplastic neurological syndromes (PNS) are remote effects of cancer on the nervous system. An overview of the management of classical PNS, i.e. paraneoplastic limbic encephalitis, subacute sensory neuronopathy, paraneoplastic cerebellar degeneration, paraneoplastic opsoclonus-myoclonus, Lambert-Eaton myasthenic syndrome and paraneoplastic peripheral nerve hyperexcitability is given. Myasthenia gravis and paraproteinemic neuropathies are not included in this report. No evidence-based recommendations were possible, but good practice points were agreed by consensus. Urgent investigation is indicated, especially in central nervous system (CNS) syndromes, to allow tumour therapy to be started early and prevent progressive neuronal death and irreversible disability. Onconeural antibodies are of great importance in the investigation of PNS and can be used to focus tumour search. PDG-PET is useful if the initial radiological tumour screen is negative. Early detection and treatment of the tumour is the approach that seems to offer the greatest chance for PNS stabilization. Immune therapy usually has no or modest effect on the CNS syndromes, whereas such therapy is beneficial for PNS affecting the neuromuscular junction. Symptomatic therapy should be offered to all patients with PNS.

X-linked adrenoleukodystrophy with olivopontocerebellar atrophy.

X-linked adrenoleukodystrophy (X-ALD) is a rare neurological disorder characterized by adrenal, gonadal and nervous system dysfunction. Patients usually develop spinal cord degeneration with involvement of the cerebral white matter. While a spinocerebellar variant has been described, the selective involvement of cerebellar white matter is very rare. We report the case of a patient affected by X-ALD whose clinical and magnetic resonance imaging (MRI) results resembled olivopontocerebellar atrophy. He was a 29-year-old mentally retarded man, who began to complain of slowly progressive gait ataxia after an 8-year history of Addison's disease. Serial MRI revealed marked cerebellar atrophy involving the inferior cerebellar vermis and brainstem, but sparing the supratentorial white matter. The diagnosis of X-ALD was confirmed by elevated levels of very long-chain fatty acids in the serum. After 2 years follow-up, the patient developed spastic paraparesis. The patient represents an unusual clinical presentation of X-ALD, as further confirmed by the MRI results. Consequently, cerebellar symptoms should be considered as a clinical presentation of X-ALD. Early recognition of this rare disorder would be useful for genetic counselling and therapy.

A rare case of paraneoplastic cerebellar degeneration discovered by whole-body F-18 FDG PET.

A rare case of paraneoplastic cerebellar degeneration (PCD) in a 36-year-old woman is reported. She developed hyposthenia of the inferior limbs, diplopia, and disequilibrium in July 2001. Routine blood tests, tumoral markers, brain MRI, evoked potentials, and cerebrospinal fluid (CSF) examination were substantially normal. The clinical syndrome rapidly worsened in the following 2 months; she was wheelchair-bound with marked limb ataxia. CSF showed an increase of the IgG index with oligoclonal bands; brain MRI remained negative. The patient's serum and CSF were analyzed to detect antineuronal antibodies; anti-Yo antibodies were found that is typical of PCD. No tumor was found until April 2003; repeated CT scan, ultrasound, and mammographic examinations were negative. A further worsening in clinical symptoms was observed with a complete loss of autonomy (Rankin score 5) despite the performance of immunosuppressive therapy. In April 2003, an F-18 FDG PET scan visualized an area of abnormal uptake in the upper outer quadrant of the left breast. Interestingly, brain F-18 FDG uptake was normal. Suspicious microcalcifications were found on a new mammography and malignant cells were disclosed at cytology. The patient was operated on and final histologic examination revealed an infiltrating ductal breast cancer. In the reported case, F-18 FDG PET played a crucial role in detecting the unknown primary tumor in a young patient with PCD.

Neurological complications of celiac disease and autoimmune mechanisms: preliminary data of a prospective study in adult patients.

Antibodies to gangliosides and Purkinje cells have been reported in patients with celiac disease (CD) with neuropathy and ataxia, respectively. Whether these antibodies are pathogenic is not clear. The response of neurological symptoms and antibody titers to a gluten-free diet is still controversial. The objective of our study was to assess whether neurological manifestations in CD patients correlate with antibody titers and a gluten-free diet.Thirty-five CD patients (9 males, 26 females, mean age 37.1 +/- 12.6 yrs) were followed prospectively. At initial evaluation, 23 were on a gluten-free diet, 12 were not. At recruitment and during follow-up, patients underwent neurological and electrophysiological evaluation. IgG, IgM, and IgA anti-ganglioside antibodies were assayed by ELISA; anti-neuronal antibodies were assessed by immunohistochemistry and Western blot. Four patients, all males, had electrophysiological evidence of neuropathy; three had been on a gluten-free diet for several months, and one was newly diagnosed. One had reduced tendon reflexes; another complained of distal paresthesias. With regard to anti-ganglioside antibodies, three patients had a moderate increase in antibodies without symptoms or signs of neuropathy. No patients had ataxia or cerebellar dysfunction, although in four patients reactivity to neuronal antigens was found. In 17 patients, an electrophysiological follow-up (mean duration of follow-up, 9 months) showed no changes. In conclusion, the preliminary results of this prospective study indicate that neuropathy, usually subclinical, may accompany CD. Antibody titers do not seem to correlate with neurological symptoms/signs or diet. Ongoing follow-up will help confirm these data and clarify the role, if any, of antibodies in neurological involvement in CD.

Antigenic differences between neurological and diabetic patients with anti-glutamic acid decarboxylase antibodies.

Antibodies to glutamic acid decarboxylase (GADAb) are found in Stiff-Person syndrome, type 1 diabetes, cerebellar ataxia and other neurological disorders (such as epilepsy and myoclonus) involving the GABAergic ways. GADAb are usually detected by immunohistochemistry (IHC), radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA). This study analysed the serum of 14 patients with neurological disorders who were positive by IHC for GADAb. The performance of a commercial RIA was compared with in-house immunoblotting and ELISA methods using recombinant GAD65 (rGAD65). RIA was positive in 14 of 14, immunoblotting was positive in seven of 14 and ELISA in 12 of 14. There was no correlation between the RIA result and the ELISA optical densities. Using a sodium thiocyanate chaotrope system with ELISA to determine antibody affinity, we found no significant correlation between antibody affinity and the RIA result. A consensus should be defined concerning which assay could be used as the gold standard for detecting GADAb. The most intriguing finding was that GAD antibodies from uncomplicated diabetics do not appear to recognize GAD in frozen sections from the rat cerebellum, whereas GAD antibodies from neurologically compromised diabetics do. A working proposal is therefore that type 1 diabetic patients with unusual neurological symptoms should be tested for GADAb both by RIA and IHC.