Current Treatments for PLS

There are no disease-modifying drugs for Primary Lateral Sclerosis. This is the honest starting point. But honest does not mean helpless: there is a meaningful range of symptom-targeted treatments that can improve daily function, reduce spasticity, and support quality of life over the long arc of the disease. This page explains what is available, what is not, and why.

The honest truth: no disease-modifying treatment for PLS in 2026

As of 2026, no drug has been approved by the FDA — or by any major regulatory agency — that slows, halts, or reverses the underlying disease process in PLS. This means there is no equivalent of riluzole for PLS, no neuroprotective agent, no gene therapy.

This is worth stating plainly, because the internet does not always do so. Searches for "PLS treatment" will return results that blur the distinction between PLS and ALS, or that present ALS drugs as options for PLS without adequate explanation of why they are not indicated. Your neurologist should be the primary source of guidance on what is available to you — and the answer, for disease modification, is currently: nothing approved.

That said, treatment in PLS is far from nothing. The disease's dominant symptom — spasticity — is treatable. Pseudobulbar affect is treatable. The functional consequences of upper motor neuron disease are addressable through therapy, equipment, and adaptation. The goal of PLS treatment in 2026 is to manage symptoms effectively enough to maintain the best possible quality of life over what is typically a decades-long disease course.

Why ALS drugs don't work for PLS

Riluzole — the first ALS drug, approved in 1995 — was the subject of a clinical trial in PLS. The trial did not demonstrate benefit. This matters because riluzole is sometimes mentioned as a "motor neuron disease drug" in ways that imply it applies to all MND conditions. It does not.

The biological mechanisms of ALS drug development are primarily targeted at lower motor neuron pathology: glutamate toxicity (riluzole), oxidative stress (edaravone), mitochondrial and ER stress (AMX0035), and gene-specific toxicity (tofersen for SOD1-ALS). PLS involves predominantly upper motor neurons. The lower motor neuron targets of ALS drug research are largely irrelevant to PLS biology.

This does not mean the two diseases share no biology — the MND spectrum concept acknowledges real overlap. But the specific mechanisms targeted by current ALS drugs do not map onto the PLS disease process in ways that have produced clinical benefit.

There is research underway to understand PLS-specific mechanisms and to identify potential treatment targets. The PLS Natural History Study and the body of work building around the 2020 consensus criteria are generating the data infrastructure that future PLS drug development will require. But as of now, none of that has produced an approved treatment.

What does work: spasticity medications

Spasticity is the defining disabling symptom of PLS — stiffness, tightness, and velocity- dependent resistance to movement in affected muscles, particularly in the legs. Effective spasticity management is central to PLS treatment and the area where the most clinical evidence exists.

Baclofen — oral and intrathecal

Baclofen is a GABA-B receptor agonist and the first-line oral medication for spasticity in PLS. It reduces abnormal muscle tone by acting on inhibitory receptors in the spinal cord and brain, reducing the excessive motor neuron firing that causes spasticity.

Oral baclofen is typically started at a low dose and increased gradually — too rapid an increase produces significant sedation and weakness. Finding the right dose involves balancing spasticity reduction against these side effects. The therapeutic window varies considerably between patients.

Side effects: Sedation, dizziness, weakness (muscle weakness is a common reason why clinicians sometimes prefer tizanidine in specific patients), nausea, and at higher doses, cognitive dulling. Abrupt discontinuation of baclofen can cause serious withdrawal reactions including seizures — doses should always be tapered.

For severe spasticity that does not respond adequately to oral baclofen, an intrathecal baclofen (ITB) pump is an evidence-supported option. The pump is a small device implanted surgically in the abdomen, delivering baclofen directly into the intrathecal space (surrounding the spinal cord) via a catheter. Because the drug is delivered directly to the target, much lower doses produce much greater effect — reducing the systemic side effects (sedation, weakness) that limit oral dosing.

Evidence from case reports and observational studies supports ITB pump use in PLS for refractory spasticity, with substantial reductions in spasticity measures and improvements in function. The pump requires surgical implantation, regular refill appointments (every one to three months), and monitoring for catheter or pump complications. It is a significant commitment, but for patients with severe refractory spasticity, the functional gains can be substantial.

Tizanidine

Tizanidine is an alpha-2 adrenergic agonist that reduces spasticity through a different mechanism than baclofen. In randomized trials comparing tizanidine and baclofen (primarily in multiple sclerosis, the closest studied population), overall patient-rated efficacy is comparable. The key practical difference is the side-effect profile:

Tizanidine causes less muscle weakness than baclofen — which can be a meaningful advantage for patients where weakness is a concern
Tizanidine causes more dry mouth and sedation (particularly at higher doses)
Tizanidine requires liver function monitoring — it can cause hepatotoxicity

The choice between baclofen and tizanidine as first-line is largely individualized based on which side effects are more acceptable for a given patient, and some patients are tried on both before settling on one. They can also be combined at lower doses of each to get benefit while minimizing individual drug side effects.

Other spasticity options

Botulinum toxin (Botox and related formulations): Injections of botulinum toxin into specific overactive muscle groups can produce targeted relaxation of focal spasticity. This is particularly useful when spasticity is prominent in specific muscle groups — for example, causing adductor scissoring in the legs, or spasticity in the forearm and hand affecting function. Botulinum toxin injections are typically given every three months and are usually coordinated with physical therapy.

Clonazepam: A benzodiazepine sometimes used for spasticity, particularly at night when spasms disrupt sleep. It carries dependence risk and requires careful prescribing. Daytime use is limited by sedation.

Diazepam: Another benzodiazepine occasionally used as an adjunct, particularly for painful spasms. Similar dependence concerns apply.

Pseudobulbar affect (PBA)

Pseudobulbar affect — episodes of involuntary laughing or crying that are disproportionate to or disconnected from your actual emotional state — occurs in PLS due to corticobulbar tract disruption. It is a neurological symptom, not a psychiatric one. It can be one of the most socially disruptive symptoms of PLS, causing significant embarrassment and isolation.

Two treatment options are used:

Nuedexta (dextromethorphan/quinidine) — the only FDA-approved medication specifically for PBA. Clinical trial evidence supports its effectiveness for reducing episode frequency and severity.
Amitriptyline — a tricyclic antidepressant commonly used off-label for PBA in the context of MND. Also addresses sialorrhea (drooling, which can co-occur with PLS in some patients with corticobulbar involvement) as a secondary benefit.

If you are experiencing episodes of involuntary laughing or crying, tell your neurologist explicitly. PBA is underdiagnosed because patients sometimes do not mention it, assuming it is a psychological symptom rather than a neurological one. It is treatable.

Physical and occupational therapy

Physical therapy (PT) and occupational therapy (OT) are central to PLS treatment — not adjuncts, but core components of care. Over a decades-long disease course, their cumulative contribution to maintained function is significant.

Physical therapy in PLS focuses on:

Maintaining range of motion in spastic muscles through stretching and positioning
Strength and balance training to compensate for motor changes
Gait training and fall prevention
Prescription and training for mobility aids (canes, rollators, wheelchairs)
Aquatic therapy, which many PLS patients find effective for spasticity management (warm water reduces tone)
Robot-aided gait training, which has shown benefit in at least one PLS case series

Occupational therapy focuses on:

Adapting daily activities to changing hand and arm function
Home assessment and modification recommendations
Assistive technology — tools that maintain independence in tasks affected by spasticity
Energy conservation strategies for managing fatigue
Driving assessment as function changes

Regular PT and OT — not just at crisis points — provides the greatest cumulative benefit. If your current care setup involves only sporadic therapy when something specific changes, advocate for more consistent access.

The multidisciplinary care advantage

Evidence in ALS consistently shows that patients treated at multidisciplinary clinics — seeing neurology, respiratory therapy, speech-language pathology, physical therapy, occupational therapy, nutrition, social work, and palliative care in coordinated visits — have better outcomes than those seeing specialists in isolation.

PLS-specific evidence for multidisciplinary care is more limited, because PLS-specific clinical infrastructure is less developed than for ALS. But the logic applies: PLS management requires coordination across neurological care, rehabilitation, and social support in ways that no single specialist can provide alone. If you are not currently being seen at a clinic with multidisciplinary capacity, a referral to an ALS/MND centre — which will typically also see PLS patients — is worth pursuing.

The 2019 EAN guideline for ALS recommends multidisciplinary care at dedicated centres and includes PLS patients within its scope. Most major ALS clinics in the US accept PLS referrals.

ALS drugs — for reference

The four FDA-approved ALS drugs are listed here for completeness, because you are likely to encounter them in reading about motor neuron disease. None are indicated for PLS:

Riluzole — first-line ALS drug; not effective in PLS (trial completed)
Edaravone — free-radical scavenger; indicated for early ALS in specific patients
Tofersen — antisense oligonucleotide for SOD1-ALS only
AMX0035 — approved 2022, withdrawn from US market 2024 after confirmatory trial failure

For more detail on ALS drug development and why ALS gets most of the research attention, see About ALS & the MND Spectrum.

Clinical trials for PLS

The most significant ongoing research activity for PLS in 2026 is the PLS Natural History Study — a prospective, multicenter study at Mayo Clinic (Rochester and Jacksonville) and Johns Hopkins, funded in part by the CDC. This is not a treatment trial, but it is generating the natural history data and biorepository that future treatment trials will require.

Participation in the Natural History Study is valuable even if you are not seeking a treatment trial — it directly contributes to the evidence base that will make future treatment possible. Ask your neurologist about eligibility.

For a full overview of active PLS trials and how to find them, see clinical trials.

Off-label considerations

Some clinicians working with PLS patients explore off-label medications for symptom management beyond the core spasticity drugs. These are not standard of care, they are not endorsed by any PLS guideline, and the evidence base is limited. They are mentioned here because patients sometimes encounter them and deserve an honest framing.

Mexiletine: Used in ALS for muscle cramps. Some neurologists consider it for PLS patients with significant cramping. Limited evidence for PLS specifically.

Cannabis-based products: Some patients report benefit for spasticity and pain from cannabis-derived medications or recreational cannabis. The evidence base for MND is limited and the route of administration matters (inhaled smoke is contraindicated in any respiratory-vulnerable patient). Where legal and accessible, some clinicians take a pragmatic approach if conventional options are inadequate.

Riluzole: Despite the negative PLS trial, some neurologists consider riluzole for PLS patients, particularly those diagnosed early or where there is uncertainty about the UMN/LMN boundary. The prescribing is off-label and the evidence does not support it; it is a decision made by individual neurologists on a case-by-case basis.

Any off-label approach should be discussed explicitly with your neurologist — what the rationale is, what outcomes are being monitored, and how long a trial will last before reassessing. Appropriate skepticism is warranted toward any treatment provider making claims not grounded in published evidence.