Ancillary Diagnostic Tests for Neurological Patients

Patient Evaluation b Signalment b History b Physical and Neurological Exams b Localization of Lesion b Differential diagnosis b Diagnostic plan b Diagnosis/Prognosis b Treatment/Evaluate

Minimum Database b CBC b Chemistry Bile acids Cholinesterase b Urinalysis b Chest and abdominal radiographs b Abdominal ultrasound b Heartworm test b Fecal

Maggie b 9 year old F/S Rottweiller b History Progressive forelimb lameness Posterior paresis Horner’s syndrome b Medications Carprofen

Maggie

MDB- -Chest Radiographs

Ancillary Neurologic Tests b Electrodiagnostics EEG EMG BAER b CSF tap & analysis Cells & protein Pressure Cholinesterase Titers b Radiographs Skull or spine Myelography CT scan MRI b Muscle Analysis Enzymes 2M antibody Anti-ACH receptor antibody Biopsy

Electrodiagnostics b EEG Measures electrical activity of the outer 3 mm of the cerebral cortex Normal activity is low amplitude, fast waves

EEG -- Normal b The normal EEG shows primarily Beta wave activity (15-30 Hz) with low amplitude (5- 15 V) b The EEG is normal in Idiopathic Epilepsy, except during a seizure.

EEG -- Encephalitis b In active encephalitis, the EEG show high- amplitude, slow- waves with spike activity.

Electrodiagnostics b EMG Evaluates the LM Unit –Cranial or spinal motor neurons –Spinal nerve root –Motor nerve –Neuromuscular junction –Muscle

Electrodiagnostics b EMG Needle EMG looks for abnormal spontaneous potentials –Fibrillation potentials –Fasciculation –Complex repetitive potentials

Electrodiagnostics b EMG Motor conduction velocity –Measured from several locations along the nerve –Disstance/Time delay for response

Electrodiagnostics b EMG F wave –Indication of integrity of the axons –Measured at 2 sites –proximal –distal

Electrodiagnostics b EMG Repetitive Nerve Stimulation –Decremental in Myasthenia gravis and OP intoxication

Electrodiagnostics b EMG Spinal Evoked Potential –Acute spinal trauma –Chronic spinal cord disease

Electrodiagnostics b BAER Evaluation of auditory system in the ear and brainstem Same instrument as for EMG

Cerebrospinal Fluid tap b Routinely done on most neurological patients b Collection from the cisterna magna (cerebellomedullary cistern) or L4-L5 lumbar space

Cerebrospinal Fluid- -CSF b Produced by the choroid plexus, ependymal cells and to a lesser extent the brain parenchyma b In the dog 0.05 ml produced/min b Propulsed by the pulsation of blood vessels

Indications for CSF Collection b Seizures b Encephalopathies b Myelopathies b Prelude to myelography b Meningiopathies and radiculopathies

Contraindications to CSF Collection b Elevated intracranial pressure b Anesthetic risk

Supplies Needed for CSF Tap b A sterile surgically prepped field b Styleted 22 ga. Spinal needles, length dependent on location. b 22 ga. Non-styleted needle for cats and small dogs. b Manometer with 3 way stop cock. b Sterile red top test tubes

Landmarks for the CSF Tap In The Dog b Cisternal b The occipital protuberance b The lateral tips of the wings of the atlas b Lumbar b The dorsal processes of L5 and L6

CSF Analysis b Pressure: less than 180mm H2O in dogs and 100mm H2O in cats. b Color and Clarity: water clear and colorless b Cellularity, under 8 cells/microliter in dogs and 5 cells/microliter in cats. An increase in cells is termed pleocytosis* b Normal cell types is small mononuclear or lymphocytes b Total protein: cisternal is less than 25 mg/dl in dogs and 20 mg/dl in cats. Less than 35 mg/dl in lumbar of dogs.

Xanthochromia CSF Color b Should be clear & colorless Try reading through it with glass tube or glass syringe

CSF Protein b Most CSF protein is albumin b Foam seen in CSF b Protein detemination Pandy: reagent is carbolic acid Nonne-Apelt: ammonium sulfate Test strips Refractive index Reference lab

CSF Protein b Levels of IgG or IgM normally very low b May be elevated if intrathecal immunoglobulin production or BBB disruption b Albuminocytologic dissociation b Albumin Quota b IgG Index

Albuminocytologic Dissociation b An increase in CSF protein without a concurrent elevation of cellularity Non-inflammatory degeneration of brain parenchyma Neoplasia Spinal cord compression

CSF Cell Count Manual Count in a Hemocytometer

CSF Cytology b Microcentrifuge b Filter collection b Sedimentation chamber

CSF Cytology

Lymphocytic pleocytosis b Seen most commonly with viral meningitis b Dogs: RV, CDV, SRM, “pug encephalitis” b Young cats: Feline polioencephalomyelitis b Lymphoma in any species

Mixed pleocytosis b Dogs: GME SRME Some Infectious b Cats: Chronic FIP

Neutrophilic pleocytosis b Always consider bacterial meningitis Can be SRMA (dogs) Can be FIP (cats) b Look for degenerative change and bacteria b Culture fluid

Eosinophilic pleocytosis b SRME with eosinophils Golden Retrievers b Infectious Parasitic migration Protozoal Algal Unconcentrated CSF from Golden with Eosinophilic SRME

Other Abnormal CSF Findings b Infectious agents b Hemorrhage b Myelin fragments b Neoplasia b Cellular inclusions b Sample contaminants

Canine Distemper Lysosomal storage disease Canine distemper Lysosomal storage disease

Cerebrospinal Fluid Analysis b Analyze RBC and WBC cell number Cytology Protein b Abnormalities Increased types of cells Increased protein Increased pressure b Titers for infectious disease Species specific

Cerebrospinal Fluid Titers b Viral Canine Distemper b Bacterial Lyme b Protozoal Toxoplasmosis Neospora b Rickettsial RMSF Ehrlichia b Fungal Aspergillus Cryptococcus b Viral FeLV FIV F IP b Protozoal Toxoplasmosis b Fungal Cryptococcus Dog Cat

Neuroradiology b Plain X-rays of head and vertebrae Bone fractures, infection, neoplasia b Myelogram Compressive and expanding spinal cord lesions b CT and MRI lesions of the head or vertebrae CT better for bone; MRI better for soft tissue

Myelography b Iohexal 0.33 ml/kg TL 0.45 ml/kg C b Inject L5-6 (or other) AO (not in small dogs b SoluMedral 15 mg/kg b Watch for seizures 5-10%

MRI Scan Normal Brain

MRI Utility b Soft tissue neoplasia b Tissue inflammation b Vascular infarction or anomalies b Neural degeneration b IVD protrusions

MRI of Lumbar Spine

When all else fails… Look at the patient!!!