Overview

Post-polio syndrome or PPS is a clinical condition that affects people who have survived polio. In PPS, new symptoms appear several years after the initial attack and a period of stability or after acute paralytic poliomyelitis. PPS's aetiology is still unknown. These symptoms include:

• Cold intolerance
• Sleep disorders
• Dysphonia 
• Dysphagia
• Respiratory deficiency
• New muscular weakness
• Exhaustion
• Pain
• Onset or aggravation of muscle atrophy
• Onset or aggravation of pre-existing difficulties in accomplishing daily life activities

Overuse of larger motor units (groups of muscle fibres controlled by a single nerve cell) may help reverse the loss of nerve function due to degeneration of distal axons (the long parts of nerve cells farthest from the body). Research shows that in partially denervated (partially nerve-deprived) muscles, muscle fibres undergo changes in both their energy usage and function. 

However, in patients with PPS, moderate aerobic training and low-intensity muscle strengthening can improve heart-lung function and muscle strength. Hence, for patients experiencing extreme fatigue, it is recommended that daily exercise routines be adjusted accordingly. Aquatic therapy has been shown to reduce pain and improve muscle function. This article explores physical therapy as a treatment regimen for PPS.¹

How is PPS diagnosed?

Since not every case will exhibit all of these symptoms, Halstead proposed diagnostic criteria in 1985, and the European Federation of Neurological Societies later confirmed them.²

The patient must fulfil the subsequent requirements to confirm a diagnosis of PPS:

• Confirmed medical history of poliomyelitis
• A period of neurological stability lasting for at least 15 years
• A partial or almost complete recovery from the acute phase of the disease
• A recent onset and rapid deterioration of muscular weakness
• At least two new symptoms among the following: extreme fatigue, joint or muscle pain, atrophy, intolerance to cold, and no other medical explanation

The primary symptom of PPS is the onset or recent aggravation of a muscular deficiency; this is an exclusion diagnosis.

Based on multiple studies, PPS appears to impact anywhere from 15 to 80% of polio survivors.^1,2

Pathophysiology of PPS

• There is debate regarding the pathophysiology of PPS. The main theories include the overuse of the denervation-reinnervation process of these enlarged motor units, which explains the rapid clinical deterioration³ 
• There’s a problem with neuromuscular conduction along immature nerve sprouts, meaning the nerves aren’t properly sending signals to the muscles. This happens because acetylcholine stores become exhausted. Doctors can see this with EMG tests using repetitive stimulation (measuring "jitters") on single fibres. Additionally, auto-immune inflammatory processes can contribute to the issue, and leftover poliovirus in the body might reactivate, causing further problems with nerve function^1,3

How is PPS treated?

Aquatic physiotherapy

For PPS and polio sequelae (long-term effects of polio), aquatic physiotherapy is the recommended course of treatment. This therapy creates ideal conditions for reducing musculoskeletal pain by allowing assisted active exercises on weakened muscles in an antigravity setting i.e., using water to reduce the strain on joints and muscles. It also includes controlled resistance training exercises where the intensity is carefully regulated to build strength. 

Positive findings from a few recent studies support this kind of physical therapy. A qualitative study by Willen and Scherman explored how people with the late effects of polio experienced dynamic exercise in water.⁴ The study found that the effects of group aquatic training went beyond just improving physical function. Participants described various experiences related to themselves, the training environment, and the surrounding world, highlighting the broader benefits of this therapy. While pain reduction was a key outcome, the study also suggested that group training in water had positive psychological and social impacts, improving overall well-being for people with PPS.⁴

Programs for strengthening muscles are especially recommended, especially in warm environments. A multicenter study by Strumse et al. examined the effects of rehabilitation in warm climates for patients with PPS.⁵ The results showed that all treatment groups improved significantly in walking ability and reported less pain, with treatment groups in warmer climates showing slightly better and longer-lasting results. In contrast, the control group showed only minimal changes. These findings suggest that rehabilitation in warm climates can have positive effects on both physical function and pain relief for PPS patients, supporting the use of aquatic physiotherapy as an effective treatment option.^1,5

Other therapies

The goals determined following an examination of the osteoarticular and muscular systems of the affected individual determine how complex the rehabilitation treatment will be. Association between various physical treatment modalities like massage, kinesitherapy, hydrothermotherapy, and occupational therapy is required to achieve optimal efficacy. 

• Massages help with relaxing muscles, reducing pain, and improving circulation
• Kinesitherapy involves therapeutic exercises which are designed to improve movement and strength.
• Hydrothermotherapy combines water and heat to reduce pain, relax muscles, and improve circulation. It’s commonly done in warm water (like in aquatic therapy)
• Occupational therapy focuses on helping individuals with daily activities (like dressing, cooking, etc.) and improving the functional capacity of individuals with PPS

The only way to limit the loss of physical ability is through rehabilitation programs that focus on movement and exercise. These therapies are crucial to the long-term management and care of individuals with PPS. The long-term prognosis for conditions like PPS is not promising, so it’s essential to regularly follow up with these individuals and enrol them in comprehensive medical rehabilitation programs. These programs are designed to maximise the individual’s ability to live independently and improve their quality of life. However, the rehabilitation process is complex and costly, affecting not only the individual but also society and the emotional well-being of both the affected individual and their families.⁶

Summary

In conclusion, years after the initial attack, people who have survived polio may develop Post-Polio Syndrome (PPS). PPS is characterised by a variety of symptoms, such as muscle weakness, exhaustion, pain, and cold intolerance, despite the fact that its aetiology is unknown. The presence of new symptoms, a period of stability followed by rapid deterioration, and a verified history of polio are necessary for the diagnosis.

Physiotherapy appears to be essential for treating PPS symptoms, especially aquatic therapy. Research shows that using aquatic therapies can effectively reduce pain and improve muscle function. Furthermore, for the best results in treating PPS, a thorough rehabilitation strategy that includes a variety of physical modalities such as massage, kinesitherapy, and occupational therapy is necessary.