New Keys to Early Diagnosis: Muscle Echogenicity, Nerve Ultrasound Patterns, Electrodiagnostic, and Clinical Parameters in 150 Patients with Hereditary Polyneuropathies

The Role of Neuromuscular Ultrasound in the Diagnosis of Peripheral Neuropathy

The classification of peripheral neuropathies has traditionally been based on etiology, electrodiagnostic findings, or histopathologic features. With the advent of modern imaging, they now can also be characterized based on their varied distribution of imaging findings. We describe the major morphologic patterns of these changes, which include homogeneous enlargement; homogeneous thinning; focal, multifocal, and segmental enlargement; and focal thinning and beading (multifocal thinning). Representative disorders in each of these categories are discussed, along with examples of the more complex imaging manifestations of neuralgic amyotrophy, nerve transection, and hereditary amyloidosis. An appreciation of the diverse morphologic manifestations of neuropathy can help neuromuscular clinicians conduct appropriate imaging studies with ultrasound and, when needed, order suitable investigations with magnetic resonance neurography.

Polyneuropathy in Cerebrotendinous Xanthomatosis: Diagnostic Challenges and Potential for Therapeutic Intervention

Cerebrotendinous xanthomatosis (CTX) is a rare metabolic disorder caused by mutations in the CYP27A1 gene, leading to cholestanol accumulation in various tissues, including peripheral nerves. Polyneuropathy is an underrecognized feature with considerable variability in clinical presentation and neurophysiological findings in CTX. This review assesses the prevalence, clinical manifestations, and diagnostic methodologies of polyneuropathy in CTX, exploring its underlying mechanisms and potential treatment outcomes. A literature review was conducted using PubMed, Embase, and the Virtual Health Library databases with search terms related to CTX and polyneuropathy. A total of 892 articles were initially identified, with 59 selected for in-depth analysis. The review focused on studies examining peripheral nerve involvement in CTX, including nerve conduction studies, electromyography, and nerve ultrasound. Polyneuropathy in CTX was observed in 50% to 77.7% of patients across multiple case series. Neurophysiological findings varied, with reports of axonal, demyelinating, and mixed polyneuropathies. Clinical presentation included lower limb atrophy, pes cavus, and distal weakness, with sensory symptoms less frequently reported. Treatment with chenodeoxycholic acid (CDCA) showed potential in improving nerve conduction parameters, although the response was variable and dependent on the timing of intervention. Polyneuropathy in CTX presents significant diagnostic challenges due to its heterogeneous presentation and varying neurophysiological findings. Early recognition and intervention are crucial for improving patient outcomes. Peripheral nerve ultrasound is a promising diagnostic tool, complementing traditional neurophysiological assessments. Further research is needed to standardize protocols and explore the full therapeutic potential of CDCA in managing CTX-related polyneuropathy.

Quantitative muscle ultrasound as a disease biomarker in hereditary transthyretin amyloidosis with polyneuropathy

INTRODUCTION

There is an increasing need for a reproducible and sensitive outcome measure in patients with hereditary transthyretin amyloidosis (ATTRv) with polyneuropathy (PN) due to the emergence of disease modifying therapies. In the current study, we aimed to investigate the role of quantitative muscle ultrasound (QMUS) as a disease biomarker in ATTRv-PN.

METHODS

Twenty genetically confirmed ATTRv amyloidosis patients (nine symptomatic, 11 pre-symptomatic) were enrolled prospectively between January to March 2023. Muscle ultrasound was performed on six muscles at standardized locations. QMUS parameters included muscle thickness (MT) and muscle echo intensity (EI). Twenty-five age- and sex-matched healthy controls were recruited for comparison. Significant QMUS parameters were correlated with clinical outcome measures.

RESULTS

Muscle volume of first dorsal interosseus (FDI) muscle [measured as cross-sectional area (CSA)] was significantly lower in symptomatic patients compared to healthy controls and pre-symptomatic carriers (98.3 ± 58.0 vs. 184.4 ± 42.5 vs. 198.3 ± 56.8, p < 0.001). EI of biceps and FDI for symptomatic ATTRv-PN patients were significantly higher compared to the other two groups (biceps: 76.4 ± 10.8 vs. 63.2 ± 11.5 vs. 59.2 ± 9.0, p = 0.002; FDI: 48.2 ± 7.5 vs. 38.8 ± 7.5 vs. 33.0 ± 5.3, p < 0.001). CSA of FDI and EI of biceps and FDI correlated with previous validated outcome measures [polyneuropathy disability score, neuropathy impairment score, Karnofsky performance scale, Rasch-built overall disability scale, European quality of life (QoL)-5 dimensions and Norfolk QoL questionnaire-diabetic neuropathy].

CONCLUSION

QMUS revealed significant difference between ATTRv amyloidosis patients and healthy controls and showed strong correlation with clinical outcome measures. QMUS serves as a sensitive and reliable biomarker of disease severity in ATTRv-PN.

Nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies

PURPOSE OF REVIEW

The purpose if this review is to provide an overview of the available data on the use of nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies.

RECENT FINDINGS

During the last decade, nerve ultrasound has been established as a complementary tool for the evaluation of morphological changes mostly for immune-mediated polyneuropathies. Through the development of ultrasound protocols for evaluation of disease-specific sites, nerve ultrasound has proven to be a practical, widely available, reproducible diagnostic tool with no relevant contraindications.

SUMMARY

Cross-sectional area, echogenicity, morphology of the individual nerve fascicles, thickness of the epineurium, vascularization and mobility of the nerve are the main parameters evaluated with nerve ultrasound in polyneuropathies. Patients with typical chronic inflammatory demyelinating polyneuropathy show multifocal nerve enlargements easily visible on the upper extremities and the brachial plexus, whereas its variants show focal nerve enlargements. On the other hand, axonal neuropathies including diabetic neuropathy present with isolated nerve enlargement mostly in compression sites.

Heterogeneous Presentation of Hereditary Neuropathy With Liability to Pressure Palsies: Clinical and Electrodiagnostic Findings in Three Patients

Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by the acute onset of focal sensory and/or motor deficits when the peripheral nerves are stressed by a mechanical force. Caused by a deletion in the PMP22 gene, this condition is often underdiagnosed or misdiagnosed due to the heterogeneity of clinical and electrophysiological presentation. This case series describes the clinical and electrodiagnostic (EDX) features of three patients presenting with clinically heterogenous phenotypes of HNPP. A retrospective analysis of patients referred to our facility for EDX studies identified three patients with genetically confirmed HNPP. The clinical presentations were unique in each patient, and the referring physicians did not consider HNPP in their differential diagnosis. The patients underwent comprehensive clinical and EDX evaluations, which led to the diagnosis of HNPP with subsequent confirmation by genetic studies. The reasons for referral for EDX studies were foot drop in one patient, carpal tunnel syndrome (CTS) in another, and wrist drop in the third patient. Patient #1 was initially diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) at another facility and developed a foot drop while recovering from a cervical discectomy and fusion. A positive family history of neuropathy led to the suspicion of hereditary neuropathy, and further studies confirmed a PMP22 gene deletion. Patient #2 gave a typical history suggestive of CTS. EDX studies showed focal slowing of conduction at potential areas of entrapment/compression. A history of foot drop in the patient and many other family members led to the confirmation of HNPP by genetic testing. US studies aided in confirming CTS by documenting a significant drop in the diameter of the median nerve within the carpal tunnel. The third patient developed radial nerve palsy after using axillary crutches. The possibility of HNPP was considered due to the pattern of nerve conduction slowing and a family history of foot drop. Physicians should be cognizant of the varied presentation of HNPP and the potential for misdiagnosis and underdiagnosis of this condition. In each case, elicitation of a detailed family history led to the suspicion of HNPP. A high index of suspicion is necessary for patients with multiple episodes of compressive neuropathies, mono/multi mononeuropathies, unexplained polyneuropathy, and a family history of neuropathy. The EDX pattern in patients presenting with acute focal neuropathies, consisting of a global increase in distal motor latencies, moderately decreased motor nerve conduction velocities, and focal slowing of conduction in potential sites of entrapment, should trigger genetic testing for HNPP.

Hereditary neuropathy with liability to pressure palsies misdiagnosed as Guillain-Barré Syndrome: A case report

RATIONALE

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominantly inherited genetic disease characterized by recurrent numbness and limb weakness. HNPP can be easily missed or misdiagnosed because of electrophysiological heterogeneity and atypical clinical symptoms. To date, diagnosis of HNPP remains a challenge for clinicians.

PATIENT CONCERNS

Here, we report the case of a 12-year-old woman diagnosed with HNPP, which was initially diagnosed with Guillain-Barré Syndrome (GBS) and treated with intravenous immunoglobulin (IVIG).

DIAGNOSES

Repeat electrodiagnostic studies and genetic testing confirmed the diagnosis of HNPP.

INTERVENTIONS

The patient was treated with neurotrophic drugs and health education, including avoiding maintenance of a certain posture for extended periods, which could damage the peripheral nerves.

OUTCOMES

The patient was discharged 5 days later. The patient was free from recurrence after 6 months of follow-up.

LESSONS

This case highlights the complexity of HNPP diagnosis and emphasizes the importance of early identification.