Novel CSF biomarkers for frontotemporal lobar degenerations

OBJECTIVE

To identify antemortem CSF diagnostic biomarkers that can potentially distinguish between the 2 main causes of frontotemporal lobar degeneration (FTLD), i.e., FTLD with TDP-43 pathology (FTLD-TDP) and FTLD with tau pathology (FTLD-tau).

METHODS

CSF samples were collected antemortem from 23 patients with FTLD with known pathology to form a autopsy cohort as part of a comparative biomarker study that additionally included 33 living cognitively normal subjects and 66 patients with autopsy-confirmed Alzheimer disease (AD). CSF samples were also collected from 80 living patients clinically diagnosed with frontotemporal dementia (FTD). Levels of 151 novel analytes were measured via a targeted multiplex panel enriched in neuropeptides, cytokines, and growth factors, along with levels of CSF biomarkers for AD.

RESULTS

CSF levels of multiple analytes differed between FTLD-TDP and FTLD-tau, including Fas, neuropeptides (agouti-related peptide and adrenocorticotropic hormone), and chemokines (IL-23, IL-17). Classification by random forest analysis achieved high sensitivity for FTLD-TDP (86%) with modest specificity (78%) in the autopsy cohort. When the classification algorithm was applied to a living FTD cohort, semantic dementia was the phenotype with the highest predicted proportion of FTLD-TDP. When living patients with behavioral variant FTD were examined in detail, those predicted to have FTLD-TDP demonstrated neuropsychological differences vs those predicted to have FTLD-tau in a pattern consistent with previously reported trends in autopsy-confirmed cases.

CONCLUSIONS

Clinical cases with FTLD-TDP and FTLD-tau pathology can be potentially identified antemortem by assaying levels of specific analytes that are well-known and readily measurable in CSF.

Impaired action knowledge in amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative condition affecting the motor system, but recent work also shows more widespread cognitive impairment. This study examined performance on measures requiring knowledge of actions, and related performance to MRI cortical atrophy in ALS.

METHODS

A total of 34 patients with ALS performed measures requiring word-description matching and associativity judgments with actions and objects. Voxel-based morphometry was used to relate these measures to cortical atrophy using high resolution structural MRI.

RESULTS

Patients with ALS were significantly more impaired on measures requiring knowledge of actions than measures requiring knowledge of objects. Difficulty on measures requiring action knowledge correlated with cortical atrophy in motor cortex, implicating degraded knowledge of action features represented in motor cortex of patients with ALS. Performance on measures requiring object knowledge did not correlate with motor cortex atrophy. Several areas correlated with difficulty for both actions and objects, implicating these brain areas in components of semantic memory that are not dedicated to a specific category of knowledge.

CONCLUSION

Patients with amyotrophic lateral sclerosis are impaired on measures involving action knowledge, and this appears to be due to at least two sources of impairment: degradation of knowledge about action features represented in motor cortex and impairment on multicategory cognitive components contributing more generally to semantic memory.

The ALSSQOL: balancing physical and nonphysical factors in assessing quality of life in ALS

BACKGROUND

There is no generally accepted instrument for measuring quality of life (QOL) in patients with ALS. Current instruments are either too heavily weighted toward strength and physical function or useful for the evaluation of individuals but of less utility in assessing large samples.

OBJECTIVE

To develop and evaluate the psychometric properties of an ALS-specific QOL instrument (the ALSSQOL) that would reflect overall QOL as assessed by the patient and would be valid and reliable across large samples.

METHODS

The ALSSQOL is based on the McGill Quality of Life Questionnaire (MQOL), modified by changes in format and by adding questions on religiousness and spirituality, items derived from interviews with ALS patients, and items identified from open-ended questions administered during the MQOL. The psychometric properties of the ALSSQOL were assessed by a prospective multicenter study in which participants completed the ALSSQOL, other instruments measuring overall QOL, and instruments assessing religiousness, spirituality, and psychological distress.

RESULTS

A 59-item ALSSQOL was developed; 342 patients evaluated its psychometric properties. Completion time averaged 15 minutes. Forty-six items loaded on six factors. The ALSSQOL demonstrated concurrent, convergent, and discriminant validity for the overall instrument and convergent validity for its subscales. Analysis of individual items permitted insight into variables of clinical importance.

CONCLUSIONS

This new ALS-specific quality of life instrument is a practical tool for the assessment of overall quality of life in individuals with ALS and appears to be valid and useful across large samples. Validation studies of a shortened version are now under way.

Multiple pathologies in a patient with a progressive neurodegenerative syndrome

A woman presenting with levodopa responsive Parkinsonism developed rapidly progressive bulbar signs, quadriparesis, and upper and lower motor neurone signs. At necropsy, she was found to have three pathological diagnoses: amyotrophic lateral sclerosis, Parkinson's disease, and abundant tau-positive argyrophilic neuritic pathology, known as argyrophilic grain disease. This case raises the possibility that three distinct neuropathological diagnoses share a common aetiology.

Postural change of forced vital capacity predicts some respiratory symptoms in ALS

The detection of respiratory muscle weakness in ALS is necessary to plan initiation of noninvasive positive pressure ventilation and begin discussion of advanced directives. The authors measured the erect seated and supine forced vital capacity (FVC) in 38 patients with ALS and 15 controls. The supine FVC is significantly lower and the erect--supine FVC difference is significantly greater in patients with complaints of dyspnea, orthopnea, and daytime fatigue.

Retinal findings in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (cadasil)

We describe a 45-year-old man with biopsy proven cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). This patient demonstrated unique retinal findings, including arteriole narrowing and sheathing, irregular choroidal filling on fluorescein angiography, and patchy visual field loss. CADASIL is a hereditary, nonamyloid, nonathersclerotic microangiopathy. This disorder has been mapped to chromosome 19 with mutations in the Notch 3 gene. Deposits of granular osmiophilic material in the basal lamina of the smooth muscle cells of small vessels are considered pathognomonic for CADASIL and are typically seen only on electron microscopy. Although CADASIL is a systemic vascular disease affecting the entire arteriole tree, we are unaware of other reports describing the retinal findings observed in our patient.

"Pseudo-conduction block" in vasculitic neuropathy

The predominant electrophysiologic feature of vasculitic mononeuropathy multiplex is axonal loss. Electrophysiologic findings interpreted as conduction block have, however, also been reported to occur in neuropathy secondary to necrotizing vasculitis. We report 3 patients with mononeuropathy multiplex and biopsy proven vasculitis in whom eight nerves met criteria for conduction block. In each circumstance, serial study demonstrated conversion of the electrophysiologic findings to those most consistent with severe axonal loss. "Conduction block" in vasculitic mononeuropathy multiplex is secondary to focal axonal conduction failure presumably related to infarctive axonal injury. The term conduction block should be used with caution in this disorder and only if serial studies demonstrate findings consistent with this electrophysiologic diagnosis.

Suprascapular neuropathy related to a glenohumeral joint cyst

A man with shoulder pain and complaints of weakness had examination findings consistent with a suprascapular neuropathy with predominant involvement of the infraspinatus muscle. Electrodiagnostic studies confirmed an axon-loss suprascapular neuropathy with greater involvement of the infraspinatus muscle. Magnetic resonance imaging (MRI) demonstrated a large ganglion cyst originating from the glenohumeral joint. The clinical, electrodiagnostic, and radiologic evaluation of suprascapular neuropathy is discussed.