Myelopathy but normal MRI: where next?

For most patients presenting with a spinal cord syndrome MR scanning has become the key investigation in establishing the diagnosis. However, myelopathy with normal spinal imaging remains a common clinical conundrum. In this review we discuss the diagnoses to consider for the neurologist presented with a patient with "MR normal myelopathy". We will illustrate this scenario with a series of short cases and consider the further investigation of "MRI normal" myelopathy.

Positive serological tests for syphilis and administration of intravenous immunoglobulin.

We report the case of a man who tested positive for syphilis following the intravenous administration of human normal immunoglobulin as part of the treatment of Guillain-Barré syndrome. The chronology of the testing suggested the passive acquisition of treponemal antibody. This phenomenon is not widely documented in the medical literature, but is a theoretical risk of treatment, and serves as a reminder to be cautious in the interpretation of such serological tests.

Neurological presentation of intravascular lymphoma: report of two cases and discussion of diagnostic challenges.

About a third of patients with intravascular lymphoma (IVL) present to the neurologist with symptoms mimicking thromboembolic events. Diagnosis is difficult, and often made postmortem. As remission may be induced in almost half of patients with combination chemotherapy, early diagnosis of this rare disease is essential. We report two cases of IVL. A 62-year-old male presented with hyperacute myelopathy followed by cortical ischaemic events. The diagnosis was reached with frontal cortical and meningeal biopsy. A 56-year-old female had symptoms of transient ischaemic events, subacute dementia, weight loss and fever. As the disease progressed, she developed nephrotic syndrome and thrombocytopenia. Diagnosis was made postmortem. Our cases illustrate that IVL should be considered in the differential diagnosis of cerebral and systemic vasculitis and subacute bacterial endocarditis. Literature suggests IVL can also mimic Creutzfeld-Jakob disease and paraneoplastic encephalomyelitis.

Pathological heterogeneity of clinically diagnosed corticobasal degeneration.

Two patients fulfilling suggested clinical diagnostic criteria for corticobasal degeneration (CBD) are presented, who were found at postmortem to have alternative pathological diagnoses not suspected during life, namely, Alzheimer's disease and Pick's disease, respectively. The nosological position of these cases is considered in light of a literature review of previous reports of clinically diagnosed corticobasal degeneration with atypical (not corticobasal degeneration) pathology. Since such phenocopies may be common, we suggest that all clinically diagnosed cases of corticobasal degeneration should initially be labelled as "corticobasal degeneration syndrome" (CBDS) to emphasize that this is a diagnosis based on clinical phenotype, with the term corticobasal degeneration being reserved for the specific neuropathological phenotype, which itself may have a variety of clinical presentations.

"CADASIL coma": an underdiagnosed acute encephalopathy.

The main clinical features of CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy) are stroke, dementia, and migraine. A reversible acute encephalopathy was the principal presentation in six of 70 patients in a British prevalence study. The episodes lasted seven to 14 days, presenting with fever, acute confusion, coma, and fits; there was full recovery but in two cases identical episodes recurred some years later. All patients had a previous history of migraine with aura and were originally misdiagnosed as viral encephalitis. CADASIL should be considered in acute unexplained encephalopathies. MRI white matter changes, previous migraine with aura, and a family history of stroke and dementia may be useful pointers to the diagnosis.

Causes of ischaemic stroke in the young.

The causes of ischaemic stroke in young adults are many and diverse. Such patients usually require more extensive investigations in order to find an underlying cause than more elderly patients. It is important that a comprehensive search is made since many of the underlying disorders are treatable. Principal causes are extracranial arterial dissection, cardioembolism, premature atherosclerosis, haematological and immunological disorders and migraine. Drug abuse is becoming increasingly important but the risk of stroke in pregnancy remains unclear. Isolated angiitis of the central nervous system, heritable disorders of connective tissue and other genetically determined disorders (mitochondrial cytopathies, CA-DASIL) account for a small proportion of ischaemic strokes in the young. Management is probably best undertaken by a physician with a specialist interest and, if full investigation fails to elucidate a definite cause, the risk of future stoke is low.

Trinucleotide (GAA)n repeat expansion in two families with Friedreich's ataxia with retained reflexes.

In occasional families in whom cases of classic Friedreich's ataxia (FRDA) coexist with affected cases with retained reflexes, linkage analysis has shown that both map to the FRDA locus on chromosome 9q13-21.1. A gene X25 has been identified within the critical region of the FRDA locus, and an intronic expanded GAA trinucleotide repeat has been found in most cases of FRDA. We report two further FRDA families in whom some patients with classic FRDA were areflexic whereas others had brisk reflexes. Molecular genetic analysis disclosed an abnormal trinucleotide repeat expansion within intron 1 of the FRDA gene in both phenotypes.

Overdiagnosis of TIA and minor stroke: experience at a regional neurovascular clinic.

We compared the referral diagnoses of TIAs and minor strokes made by non-specialists with those of two consultant neurologists, in 565 consecutive cerebrovascular clinic patients, of whom 508 (90%) were referred with a diagnosis of any TIA or stroke. In 373 (73%), the neurologists felt the diagnosis of a cerebrovascular event to be correct. Agreement with the vascular syndrome (CVA vs. TIA) was significantly higher for patients with a referral diagnosis of stroke (136/176) (77%) than it was for patients with a referral diagnosis of TIA (200/332) (60%) (difference in proportions 17%, 95% CI 9-25). In 37 patients (7%) the neurologists confirmed the diagnosis of cerebrovascular disease but not the specific TIA/stroke diagnosis. Vascular surgeons were more likely to be correct in their referral diagnosis of carotid territory cerebrovascular disease (88% correct) than all other sources combined (63% correct) (difference in proportions 25%, 95% CI 11-39), but there was no significant variation in diagnostic accuracy between other individual groups. In 135/508 patients (27%) referred as any TIA or stroke, the diagnosis of cerebrovascular disease was undone. Alternative diagnoses included migraine (3%), epilepsy (1%), hyperventilation (1%), multiple sclerosis (1%) and a case of idiopathic Parkinson's disease, but many symptoms (8%) were unclassifiable. A strict comparison of diagnostic accuracy would have required assessment of patients not referred for specialist opinion, to estimate false-negative as well as false-positive diagnoses. However, in this patient group (which reflects current local practice) TIAs and strokes seem overdiagnosed.

Cerebral venous thrombosis.

Cerebral venous thrombosis is a treatable and under-recognised cause of a benign intracranial hypertension syndrome, and may also cause focal signs, seizures, and depression of consciousness.

Autosomal dominant cerebellar ataxia with pigmentary macular dystrophy. A clinical and genetic study of eight families.

We describe 54 members of eight families with a distinct autosomal dominant cerebellar ataxia associated with visual failure secondary to a pigmentary macular dystrophy. The presenting symptom was ataxia in two-thirds of patients and visual failure or both in the remainder. The macular abnormalities were often subtle in early cases, even in some with moderately reduced visual acuity. Other neurological features included pyramidal tract signs and a supranuclear ophthalmoplegia with progressive saccadic palsy. Ages of onset and clinical course were very variable, even within families, and included a rapidly progressive, infantile-onset phenotype. Pedigree analysis showed the existence of non-manifesting obligate carriers and anticipation in the offspring of affected fathers; transmission of the disease to severe, infantile-onset cases was always from an affected father. Similar genetic phenomena have been reported in myotonic dystrophy and Huntington's disease and it is likely that the gene mutation in this condition will similarly consist of an unstable trinucleotide repeat expansion.