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PubMed This is a summary of 17 peer-reviewed journal articles Updated
Neurology · HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis

Diagnostic Criteria and Lab Results for HAM/TSP

At a Glance

HAM/TSP is diagnosed by confirming HTLV-1 infection, matching the person’s symptoms and examination, and ruling out other causes of spinal cord problems. Blood tests, spinal fluid analysis, MRI, and formal criteria may all contribute, and a normal early MRI does not exclude it.

Diagnosing HAM/TSP is a process of both confirmation and exclusion. Because its symptoms overlap with many other neurological conditions, doctors use a combination of specialized blood tests, clinical examinations, imaging, and sometimes spinal fluid analysis to be certain of the diagnosis [1][2].

Confirming the Virus: Blood Testing

The first essential step is proving that the HTLV-1 virus is present in your blood. This requires a two-step testing process [3]:

  1. Screening (ELISA): A highly sensitive blood test looks for antibodies to the virus.
  2. Confirmation (Western Blot or PCR): If the screening is positive, a second, more specific test—either a Western Blot (which identifies specific viral proteins) or a PCR (which looks for the virus’s genetic material)—is used to confirm the result and ensure it is not HTLV-2, a related but different virus [4][5].

The Role of Spinal Fluid (CSF) Analysis

A lumbar puncture (spinal tap) is often performed to analyze your Cerebrospinal Fluid (CSF), the liquid that surrounds your brain and spinal cord [6][7]. While finding HTLV-1 antibodies in the CSF is highly supportive of a “definite” HAM/TSP diagnosis under standard criteria, a lumbar puncture may not be strictly mandatory for every patient if the clinical picture, blood work, and exclusion tests strongly point to the disease.

When a lumbar puncture is done, doctors look for markers of inflammation:

  • Elevated Protein and Cells: A slightly high protein level or white blood cell count in the CSF is common and signals ongoing inflammation [8][9].
  • Oligoclonal Bands: These are proteins that indicate immune system activity in the central nervous system. They are not specific to HAM/TSP (they are also common in multiple sclerosis) but provide a piece of the diagnostic puzzle.
  • Adjunctive Biomarkers (Proviral Load, CXCL10, Neopterin): Some specialized centers or research trials measure these to track disease activity. CXCL10 and Neopterin are proteins that act as signals for the immune system, and a high proviral load measures how many cells carry the virus. Note: These biomarkers are not universally standardized or available at all clinics, and their exact role in everyday treatment decisions is still being studied [10][11][12].

The Role of MRI

An MRI (Magnetic Resonance Imaging) scan is used to look for physical changes in the spinal cord. In many people with HAM/TSP, the MRI will eventually show spinal cord atrophy, which is a thinning or shrinking of the cord, particularly in the middle (thoracic) or upper (cervical) back [13][14].

However, the main purpose of an MRI during diagnosis is to rule out structural causes of your symptoms, such as a tumor, a herniated disc pressing on the nerves (compressive myelopathy), or spinal stenosis [15]. A “normal” MRI does not rule out HAM/TSP, especially in the early stages.

Ruling Out “Look-Alike” Conditions

Because there is no single test that can prove HAM/TSP on its own in every case, your medical team must exclude other conditions that cause similar leg weakness and stiffness. This “rule-out” list typically includes:

  • Multiple Sclerosis (MS): Which can cause similar walking difficulties but often shows different patterns on a brain and spinal MRI [2].
  • Nutritional Deficiencies: Your doctor will order specific blood tests to check your Vitamin B12 and Copper levels, as deficiencies in these nutrients can damage the spinal cord.
  • Other Infections: Blood tests for HIV, syphilis, and certain types of hepatitis are necessary, as these can also affect the spinal cord.

Diagnostic Criteria: Osame and Castro-Costa

Your doctor likely evaluated your case using formal guidelines like the Osame Criteria (1990) or the Castro-Costa Criteria (2006) [16]. These systems group patients into “Definite,” “Probable,” or “Possible” HAM/TSP based on clinical signs, blood confirmation, and CSF results [16][17]. Understanding these criteria helps your doctor ensure that other potential causes have been safely excluded.

Common questions in this guide

Which blood tests are used to confirm HAM/TSP?
Doctors usually begin with an ELISA blood test that looks for antibodies to HTLV-1. If it is positive, Western blot or PCR is used to confirm the infection and help distinguish HTLV-1 from HTLV-2.
Do I need a lumbar puncture to be diagnosed with HAM/TSP?
A lumbar puncture can look for HTLV-1 antibodies and signs of inflammation in cerebrospinal fluid. CSF antibodies strongly support a definite diagnosis under standard criteria, but a spinal tap is not always required when the symptoms, blood tests, and exclusion workup are otherwise convincing.
What can my CSF results show in HAM/TSP?
CSF may show mildly increased protein or white blood cells, which can indicate inflammation. Oligoclonal bands may also appear, but they are not specific to HAM/TSP; specialized markers such as proviral load, CXCL10, and neopterin are not standardized or available everywhere.
Can an MRI rule out HAM/TSP?
MRI is mainly used to look for other causes of spinal cord symptoms, such as a tumor, spinal stenosis, or pressure from a herniated disc. Spinal cord thinning may develop in HAM/TSP, but a normal MRI, especially early in the illness, does not rule it out.
What other conditions must be ruled out before diagnosing HAM/TSP?
Doctors may check for multiple sclerosis, vitamin B12 or copper deficiency, HIV, syphilis, and certain hepatitis infections. Imaging and other tests may also be used to exclude a tumor or physical pressure on the spinal cord.
What do the Osame and Castro-Costa criteria mean?
These are formal systems used to organize HAM/TSP findings into definite, probable, or possible categories. They consider the neurological examination, HTLV-1 blood confirmation, cerebrospinal fluid results, and whether other causes have been excluded.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Do my test results meet the Castro-Costa 'Definite' or 'Probable' criteria for HAM/TSP?
  2. 2.What was my HTLV-1 proviral load in my blood tests?
  3. 3.Has my CSF been tested for the inflammatory markers CXCL10 or neopterin, or is that primarily for research?
  4. 4.Can you walk me through how my MRI ruled out structural problems like a compressed nerve?
  5. 5.Does my Western Blot or PCR test clearly distinguish between HTLV-1 and HTLV-2?
  6. 6.Were there any oligoclonal bands in my CSF, and how did that fit into the broader diagnostic picture?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (17)
  1. 1

    Neuroimmunology of Human T-Lymphotropic Virus Type 1-Associated Myelopathy/Tropical Spastic Paraparesis.

    Nozuma S, Jacobson S

    Frontiers in microbiology 2019; (10()):885 doi:10.3389/fmicb.2019.00885.

    PMID: 31105674
  2. 2

    Advances in the treatment of human T-cell lymphotropic virus type-I associated myelopathy.

    Mashkani B, Jalili Nik M, Rezaee SA, Boostani R

    Expert review of neurotherapeutics 2023; (23(12)):1233-1248 doi:10.1080/14737175.2023.2272639.

    PMID: 37933802
  3. 3

    HTLV-1 infection in patients with neurological manifestations in Northeast Brazil.

    da Silva AFS, da Silva Bastos YC, Oikawa JT, et al.

    Journal of neurovirology 2026; (32(4)).

    PMID: 42406190
  4. 4

    HTLV-1 intrafamilial transmission among Japanese immigrants in Brazil.

    Bandeira LM, Uehara SNO, Puga MAM, et al.

    Journal of medical virology 2018; (90(2)):351-357 doi:10.1002/jmv.24938.

    PMID: 28876483
  5. 5

    Human T-Lymphotropic Virus (HTLV): Epidemiology, Genetic, Pathogenesis, and Future Challenges.

    Branda F, Romano C, Pavia G, et al.

    Viruses 2025; (17(5)) doi:10.3390/v17050664.

    PMID: 40431676
  6. 6

    Immunophenotypic characterization of CSF B cells in virus-associated neuroinflammatory diseases.

    Enose-Akahata Y, Azodi S, Smith BR, et al.

    PLoS pathogens 2018; (14(4)):e1007042 doi:10.1371/journal.ppat.1007042.

    PMID: 29709026
  7. 7

    A refractory human T-cell leukemia virus type 1-associated myelopathy/tropical spastic paraparesis patient with lymphoma-type adult T-cell leukemia/lymphoma: A case report and review of the literature.

    Tamaki K, Mera H, Takeshita S, et al.

    Medicine 2021; (100(40)):e27450 doi:10.1097/MD.0000000000027450.

    PMID: 34622865
  8. 8

    HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP): A comparative study to identify factors that influence disease progression.

    Matsuura E, Nozuma S, Tashiro Y, et al.

    Journal of the neurological sciences 2016; (371()):112-116 doi:10.1016/j.jns.2016.10.030.

    PMID: 27871430
  9. 9

    Immunovirological markers in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP).

    Enose-Akahata Y, Jacobson S

    Retrovirology 2019; (16(1)):35 doi:10.1186/s12977-019-0499-5.

    PMID: 31783764
  10. 10

    Following the Clues: Usefulness of Biomarkers of Neuroinflammation and Neurodegeneration in the Investigation of HTLV-1-Associated Myelopathy Progression.

    Souza FDS, Freitas NL, Gomes YCP, et al.

    Frontiers in immunology 2021; (12()):737941 doi:10.3389/fimmu.2021.737941.

    PMID: 34764955
  11. 11

    An update on human T-cell leukemia virus type I (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) focusing on clinical and laboratory biomarkers.

    Yamauchi J, Araya N, Yagishita N, et al.

    Pharmacology & therapeutics 2021; (218()):107669 doi:10.1016/j.pharmthera.2020.107669.

    PMID: 32835825
  12. 12

    Neurological Manifestations in Human T-Cell Lymphotropic Virus Type 1 (HTLV-1)-Infected Individuals Without HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis: A Longitudinal Cohort Study.

    Tanajura D, Castro N, Oliveira P, et al.

    Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2015; (61(1)):49-56 doi:10.1093/cid/civ229.

    PMID: 25820277
  13. 13

    Cerebral and spinal cord changes observed through magnetic resonance imaging in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis: a systematic review.

    Bastos Ferreira AP, do Nascimento ADFS, Sampaio Rocha-Filho PA

    Journal of neurovirology 2022; (28(1)):1-16 doi:10.1007/s13365-021-01043-2.

    PMID: 34981435
  14. 14

    Spinal cord anteroposterior atrophy in HAM/TSP: Magnetic resonance imaging and neuropathological analyses.

    Taniguchi A, Mochizuki H, Yamashita A, et al.

    Journal of the neurological sciences 2017; (381()):135-140 doi:10.1016/j.jns.2017.08.3243.

    PMID: 28991665
  15. 15

    Multiple spotty lesions of the spinal cord in a Chinese patient with human T-lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis.

    Gao H, Ye X, Cai R, et al.

    International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases 2018; (68()):1-3 doi:10.1016/j.ijid.2017.12.022.

    PMID: 29292042
  16. 16

    Early Juvenile Human T-cell Lymphotropic Virus Type-1-Associated Myelopathy/Tropical Spastic Paraparesis: Study of 25 Patients.

    Varandas CMN, da Silva JLS, Primo JRL, et al.

    Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2018; (67(9)):1427-1433 doi:10.1093/cid/ciy289.

    PMID: 29912303
  17. 17

    Association of Tuberculosis Status with Neurologic Disease and Immune Response in HTLV-1 Infection.

    Souza A, Carvalho N, Neves Y, et al.

    AIDS research and human retroviruses 2017; (33(11)):1126-1133 doi:10.1089/AID.2015.0340.

    PMID: 28540757

This page explains HAM/TSP diagnostic tests and criteria for informational purposes only and does not constitute medical advice. Your neurologist or other clinician should interpret your results and discuss your diagnosis with you.

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