Heme Onc Flashcards
1
Q
Eaton-Lambert Syndrome
A
Lambert-Eaton has antibodies to presynaptic calcium channels
Very similar presentation to myasthenia but Lambert-Eaton syndrome less likely to cause ocular symptoms and gives absent reflexes. EMG also helps to differentiate.
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LAMBERT-EATON SYNDROME
- Autoimmune downregulation of the presynaptic voltage-gated Ca2+ channels by channel specific Ab, results in inadequate release of ACh from pre-synaptic nerve terminals.
- Associated with malignancy (especially small cell lung carcinoma)
- ~40-60% have SCLC at the time of presentation or will be diagnosed with it within 2 years
- Otherwise: NSCLC, Prostate, Breast, Lymphoma
- Fatigability and weakness of the proximal limb skeletal muscles
- Deep tendon reflexes are almost always depressed or absent.
- No sensory or coordination abnormalities
- Bulbar/ocular symptoms are uncommon (unlike myasthenia gravis)
- Prominent anticholinergic autonomic symptoms: dry mouth, impotence, orthostatic hypotension, constipation, difficult micturation, blurred vision
- EMG shows paradoxical increase in response with successive muscle contractions with rapid (>10Hz) repetitive stimulation, muscle fatigability with repetitive slow stimulation, poor response to edrophonium
- Screen for malignancy; especially SCLC
- Management
- Treat the underlying cancer
- Acetylcholine modulation
- increase acetylcholine release: 3-4 diaminopyridine
- decrease acetylcholine degradation: pyridostigmine
- Immunomodulation
- steroids, plasmapheresis/PLEX, IVIg
2
Q
Paraneoplastic syndromes (antibodies)
A
Anti-HU Anti-Yo (PCA) Anti-Purkinje Anti-CA (VGCC) Anti-AChR Anti-NMDAr
3
Q
Paraneoplastic syndromes (Neurologic)
A
1) Subacute Sensory Neuronopathy (80% SCLC, usu anti-Hu) – typically loss of vibratory sensation and joint position à impairment in pain and temperature sensation
- Complain of the sensation of “pins and needles” or “electric shocks. Usually start from legs à usually progress to involve other extremities, the face, abdomen, or trunk in weeks to months.
- May include sensorineural hearing loss, diminished taste sensation, and symmetric or asymmetric reduction or loss of deep tendon reflexes.
- Among patients with subacute sensory neuronopathy who have anti-Hu antibodies and SCLC, many progress to paraneoplastic encephalomyelitis
- Cisplatin produces a large fiber neuropathy affecting position and vibration sense almost exclusively and sparing pin and temperature sense, whereas the paraneoplastic disorder affects all sensory modalities.
2) Chronic Sensorimotor neuropathy
- Approximately 10 to 15 percent of patients with solid tumors (most lung CA)
- Symptoms typically develop in patients with advanced disease,
- Not very debilitated by their neurologic symptoms, which typically consist of mild to moderate distal symmetric sensorimotor deficits. Nerve conduction studies are consistent with an axonal neuropathy, but decreased conduction velocities such as with demyelination may be seen.
- Cancer treatment and disorders unrelated to malignancy such as diabetes, alcoholism, and vitamin B12 deficiency.
- Some forms may harbor anti-CV2 (or CRMP5) antibodies; these antibodies usually associate with SCLC or thymoma. These neuropathies are very disabling and respond poorly to immunotherapy or treatment of the tumor.
3) Paraneoplastic Autonomic Neuropathy
4
Q
Spinal metastases
A
5
Q
Spinal Cord Compression (ESCC)
A
6
Q
Cauda Equina Syndrome
A
- Low back pain accompanied by pain radiating into one or both legs. Radicular pain reflects involvement of dorsal nerve roots and may have localizing value [21].
- Weakness of plantar flexion of the feet with loss of ankle jerks occurs with mid cauda equina lesions, involving S1, S2 roots. Involvement of progressively higher levels leads to corresponding weakness in other muscles
- Bladder and rectal sphincter paralysis usually reflect involvement of S3-S5 nerve roots.
- Sensory loss of all sensory modalities occurs in the dermatomal distribution of the affected nerve roots
