Morvan syndrome associated with CASPR2/LGI1 antibody positivity and thymoma successfully managed with plasmapheresis and radical thymectomy

Leema Rebekal Rosy1*, Bhuvaneshwari2, Esthar Rani3

1Deputy Nursing Superintendent, Kauvery Hospital, Tennur, Trichy, Tamil Nadu

2Assistant Nursing Superintendent, Kauvery Hospital, Tennur, Trichy, Tamil Nadu

3Nursing Superintendent, Kauvery Hospital, Tennur, Trichy, Tamil Nadu

*Correspondence

Abstract

Morvan syndrome is a rare autoimmune neurological disorder characterized by peripheral nerve hyper excitability, autonomic dysfunction, sleep disturbances, and neuropsychiatric manifestations. It is frequently associated with antibodies against contactin-associated protein-like 2 (CASPR2) and less commonly with leucine-rich glioma-inactivated protein 1 (LGI1). Thymoma is an important paraneoplastic association.

We report a 42-year-old male who presented with generalized tremulousness, severe weight loss, insomnia, autonomic dysfunction, numbness of lower limbs, erectile dysfunction, and generalized fasciculations. Neurological examination revealed tongue fasciculations and diffuse muscle wasting. Electromyography demonstrated positive sharp waves, fibrillation potentials, and complex repetitive discharges suggestive of peripheral nerve hyper excitability. Autoimmune encephalitis panel showed strong positivity for CASPR2 and LGI1 antibodies. PET-CT revealed a thymic lesion in the anterior mediastinum. The patient was treated with five cycles of plasmapheresis followed by Video-Assisted Thoracoscopic Surgery (VATS) radical thymectomy. Significant clinical improvement was observed following immunotherapy and surgery.

This case highlights the importance of recognizing Morvan syndrome in patients presenting with unexplained autonomic symptoms, fasciculations, insomnia, and weight loss, and demonstrates favourable outcomes with combined immunotherapy and thymectomy.

Key words: Morvan syndrome; Video-Assisted Thoracoscopic Surgery (VATS)

Introduction

Morvan syndrome is a rare autoimmune disorder affecting both the peripheral and central nervous systems. The syndrome is characterized by neuromyotonia, peripheral nerve hyper excitability, autonomic dysfunction, severe insomnia, neuropsychiatric manifestations, and constitutional symptoms. Most cases are associated with antibodies directed against voltage-gated potassium channel complex proteins, particularly CASPR2 and LGI1.

Approximately one-third of patients have an associated thymoma, suggesting a paraneoplastic mechanism. Due to its rarity and varied presentation, diagnosis is often delayed. Early recognition and treatment are essential to prevent progressive neurological impairment and improve functional outcomes.

We describe a patient with Morvan syndrome associated with CASPR2/LGI1 positivity and thymoma who demonstrated marked clinical improvement following plasmapheresis and surgical thymectomy.

Case Presentation

A 42-year-old gentleman presented with complaints of generalized tremulousness involving the entire body for three months. The symptoms were associated with significant unintentional weight loss of approximately 10 kilograms despite preserved appetite. He also reported: Sleep disturbance and severe insomnia, Difficulty in passing urine, Difficulty in passing stools, Numbness and tingling sensation in both feet, Erectile dysfunction, Back pain, Progressive generalized weakness. There was no history of fever, seizures, cranial nerve involvement, bulbar weakness, smoking, alcohol consumption, or similar illness in the past.

Clinical Examination

On examination, the patient was conscious, alert, and oriented.

Vital Signs

  • Pulse rate: 114/min
  • Blood pressure: 130/70 mmHg
  • Oxygen saturation: 98% on room air

General Examination

The patient appeared thin built with significant muscle wasting involving: Shoulder girdle, Hand muscles, Hip girdle, Calf muscles, Facial muscles, Temporal hollowing was noted. Tongue fasciculations were present.

Generalized fasciculations were observed over:

  • Thighs, shoulders, back muscles
  • Neurological examination: Speech was normal.
  • Motor examination revealed: Normal tone in all four limbs, muscle power 5/5 in all limbs
  • Deep tendon reflexes preserved, Bilateral plantar flexor response
  • No cerebellar signs or meningeal signs were present.

Investigations

EMG demonstrated:

These findings were suggestive of peripheral nerve hyper excitability.

Nerve Conduction Study

Nerve conduction study was within normal limits.

Autoimmune encephalitis profile revealed: Strong positivity for CASPR2 antibodies

Strong positivity for LGI1 antibodies, CASPR2 antibodies,

These findings strongly supported the diagnosis of Morvan syndrome.

PET-CT demonstrated:

  • Well-defined complex cystic lesion in the left anterior mediastinum
  • Mild FDG uptake
  • Features suggestive of thymic origin
  • No distant metabolically active lesions were identified.
  • Echocardiography
  • Normal chamber dimensions
  • Ejection fraction 60%
  • No significant structural abnormality

Diagnosis

Based on clinical presentation, electrophysiological findings, antibody positivity, and imaging studies, a diagnosis of: Morvan Syndrome Associated with Thymoma was established.

Therapeutic Intervention

The patient underwent:  Immunotherapy

Five cycles of therapeutic plasmapheresis were administered.

Supportive medical treatment included:

  • Corticosteroids
  • Benzodiazepines
  • Vitamin supplementation
  • Symptomatic management

Following plasmapheresis, significant improvement was observed in: Fasciculations, Sleep disturbances, Appetite, Autonomic symptoms

Surgical Management

Subsequently, the patient underwent:

  • Video-Assisted Thoracoscopic Surgery (VATS) Radical Thymectomy
  • Intraoperative findings revealed:
  • Thymic mass measuring approximately 5 × 5 cm
  • Lesion arising from thymic tissue
  • Complete excision achieved
  • The postoperative period was uneventful.

Outcome and Follow-Up

Following combined immunotherapy and thymectomy:

  • Fasciculations reduced markedly
  • Sleep improved significantly
  • Appetite improved
  • Weight stabilized
  • Autonomic dysfunction improved
  • Functional status improved
  • The patient remained neurologically stable and was discharged with advice for regular follow-up.

Discussion

Morvan syndrome is an uncommon autoimmune neurological disorder characterized by peripheral nerve hyperexcitability, autonomic dysfunction, and central nervous system manifestations. The disease is strongly associated with antibodies against CASPR2 and, less frequently, LGI1. The present patient demonstrated several classical manifestations of Morvan syndrome, including generalized fasciculations, severe insomnia, autonomic dysfunction, erectile dysfunction, constipation, urinary difficulties, and profound weight loss. Electrophysiological findings were consistent with peripheral nerve hyperexcitability. An important feature of this case was the identification of a thymic lesion. Thymoma-associated Morvan syndrome represents a recognized paraneoplastic phenomenon. The thymus may play a critical role in autoantibody production and immune dysregulation. Current evidence suggests that immunotherapy, including corticosteroids, intravenous immunoglobulin, and plasmapheresis, forms the cornerstone of treatment. In patients with thymoma, surgical resection is recommended and may contribute to sustained neurological recovery. Our patient showed significant improvement after plasmapheresis and further stabilization following radical thymectomy, supporting the role of combined immunomodulatory and surgical therapy.

Nursing Management

Nursing Diagnosis 1

Imbalanced Nutrition Less Than Body Requirements

Related to: Hypercatabolic state and chronic illness

Evidenced by 10 kg weight loss and muscle wasting

Interventions

  • Daily weight monitored
  • High-protein diet
  • Nutritional supplementations were given
  • Dietician consultation was done
  • Monitored serum albumin

Outcome: Appetite improved and weight stabilized.

Nursing Diagnosis 2

Disturbed Sleep Pattern

Related to: Neurological hyperexcitability

Interventions

  • Promoted sleep hygiene
  • Minimized the environmental disturbances
  • Administered prescribed medications
  • Monitor sleep quality

Outcome: Improved sleep duration and quality.

Nursing Diagnosis 3

Chronic Pain

Related to: Neuromuscular hyperexcitability

Interventions

  • Pain assessment done, Pharmacological management done
  • Positioning and comfort measures provided
  • Relaxation techniques advised

Outcome: Pain reduced.

Nursing Diagnosis 4

Activity Intolerance

Related to: Muscle wasting and fatigue

Interventions: Gradual mobilization, active and passive exercise done

Outcome: Improved functional independence.

Nursing Diagnosis 5

Risk for Autonomic Dysfunction

Interventions

  • Monitored vital signs
  • Assessed bowel and bladder function
  • Monitored hydration status
  • Evaluate orthostatic changes

Outcome: Hemodynamic stability maintained.

Nursing Diagnosis 6

Anxiety

Related to: Rare neurological illness and surgery

Interventions

  • Psychological support, Emotional support given
  • Family involvement in Counselling

Outcome: Reduced anxiety and improved coping.

Conclusion

Morvan syndrome is a rare but potentially reversible autoimmune neurological disorder. The presence of unexplained fasciculations, insomnia, autonomic dysfunction, and weight loss should prompt evaluation for peripheral nerve hyperexcitability disorders and associated thymoma. Early diagnosis through antibody testing and electrophysiological studies is crucial. This case demonstrates that combined plasmapheresis and thymectomy can lead to substantial neurological recovery and improved quality of life.

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