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Paraneoplastic Phenomenon. 1 2

Neurological Paraneoplastic Syndromes

Paraneoplastic neurological syndromes (PNS) = Remote effects of cancer that are not caused by tumour, mets, infection, ischaemia or metabolic disruption.

Rare. \<1 in 10,000 with Ca. Commonly the presentation of the tumour but often the System review is positive.
Immune mediated by 2 types of antibodies.

Clinical Features
- Subacute, progressive or consecutive involvement of different areas of NS.

1) ONCONEURONAL ANTIBODIES

Are antibodies against intracellular Ag seen in both tumour and the nervous system.
If positive on serology then very high PPV of having tumour. Thus needs Ix.
But, poor prognosis, often refractory and relentless progressive.

Tumours most often associated.
  • Lung esp NSCLC
  • Breast and Ovarian.
  • Testicular in young M. (anti-Ma)
Common PNSs are
  1. Paraneoplastic Cerebellar Degeneration (PCD) 25%
  2. Paraneoplastic Limbic Encephalitis (PLE) 10%
  3. Paraneoplastic Encephalomyelitis (PEM) 6%

2) NEURONAL CELL-SURFACE ANTIBODIES

Against receptors/proteins at synaptic or extra-synaptic neuronal cell membrane.
Much more common but often not assoc'd with underlying tumours.

40% of anti-NMDA receptor encephalitis have associated underlying tumours.

Antibodies and Syndromes

Neuro paraneoplastic syndromes

Types.

Name Path Radiology Other
Limbic Encephalitis (LE) Both Onconeuronal Ab such as Anti-Hu in SCLC.
And, Neuronal cell surface Ab.		 MRI +ve in 50%.
T2/FLAIR ++
Gd 0/+
ADC 0/+		 NH: Can lead to mesotemporal sclerosis.
Paraneoplastic Cerebellar Degeneration (PCD) Onconeuronal most common. Anti-Yu and Anti-Hu common.
CF: Rapid onset ataxia, dysarthria, nystagmus.		 MRI usu Normal
CSF usually positive and inflam = lymphatic pleocytosis +/- oligoconal bands.		 NH: Stabilises but with poor function.
Anti-NMDA Receptor Encephalitis Young Women. 80% F. 95% <45yo
CF: Prodrome of Fever, Headache, N/V, then Psych/Behaviour abn. 70% = STM defects. 70% Seizures.
Path: Ovarian Teratoma (94% of 12-45yoF)
Only 6% of M have underlying malignancy.		 MRI = 50% Sens.
T2/FLAIR ++ in hippocampi, cerebellum, cerebral cortex, insula, BGs, brain stem & spinal cord occ.
But, usually mild/transient.

Clinical Notes

Screening for tumours Follow Guidelines Sometimes small but most manifest in <1y Onco F/U 3-6 monthly for 5y

Treatment
1) Onconeuronal Ab = Rx tumour = stabilise symptoms and stop progression (but with poor response from Immuno)
2) Neuronal Cell Surface Ab = Respond well to tumour removal and immunosuppression.

  1. https://www.clinicalkey.com/#!/content/derived_clinical_overview/76-s2.0-B9780323755702006809 "Clinical Key" ↩

  2. Husband & Resnek Imaging in Oncology. 4e. ↩