Ahpra registration PHY0002298174
How these guides are written and reviewed →
The thymus is a small gland behind the breastbone. It can grow a tumour, and it also drives the immune attack that causes myasthenia gravis — a condition where muscles tire quickly, including the muscles used to breathe and swallow. Removing the gland can reduce the disease over months to years. After the operation, breathing and swallowing need close watching, and exercise has to be paced carefully, because in this condition muscles get weaker with repetition rather than stronger.
The problem being fixed
Thymectomy is performed for two largely separate indications, and conflating them causes clinical errors.
- Thymoma. A tumour of the thymic epithelium, resected for oncological reasons. Around a third of patients with thymoma also have myasthenia gravis, but many do not, and in those the post-operative course resembles any other anterior mediastinal resection.
- Non-thymomatous myasthenia gravis. Removal of a macroscopically normal gland as immunomodulatory treatment. Myasthenia gravis (MG) is an autoantibody-mediated disorder of the neuromuscular junction, most commonly against the acetylcholine receptor (AChR), producing fatigable weakness that worsens with sustained or repeated effort and recovers with rest.1
The distinguishing feature of MG for a physiotherapist is that weakness is not fixed. Strength measured at the start of a session may be substantially better than strength ten repetitions later, and a patient can look safe on arrival and be in respiratory difficulty an hour afterwards.
What the operation involves
Extended transsternal thymectomy removes the gland with surrounding mediastinal fat and remains the reference approach, and was the technique used in the pivotal trial. Minimally invasive alternatives — video-assisted thoracoscopic surgery (VATS) and robotic-assisted thymectomy — are widely used, with shorter stay and less pain, though the randomised evidence sits with the open operation.
Pre-operative optimisation matters more here than in most thoracic surgery. Plasma exchange or intravenous immunoglobulin is often given to reduce the risk of post-operative respiratory failure, and pyridostigmine and immunosuppression are adjusted around the procedure. Neuromuscular blocking agents are used with great caution because sensitivity is markedly increased.
Who benefits — and what the evidence shows
The Thymectomy Trial in Non-Thymomatous Myasthenia Gravis (MGTX) randomised 126 patients with generalised, AChR-antibody-positive MG under 65 years to extended transsternal thymectomy plus prednisone or prednisone alone.2 Over three years the surgical group had lower Quantitative Myasthenia Gravis scores, required less prednisone, had fewer hospitalisations for exacerbation and needed less rescue therapy. Benefit persisted at five years.3
Two qualifications matter clinically. Improvement is slow, accruing over months to years rather than weeks — a patient expecting to feel better on discharge has been poorly counselled. And the evidence base is narrower than the operation's use: MGTX excluded patients over 65, those with purely ocular disease, and antibody-negative patients, in whom benefit is far less certain.4
Post-operative myasthenic crisis
Myasthenic crisis is respiratory failure from neuromuscular weakness, and it can develop over hours. Falling vital capacity, weak cough, nasal or slurred speech, difficulty swallowing saliva and orthopnoea are the warning signs. Arterial blood gases and oxygen saturation are late indicators — a patient can be saturating normally while approaching intubation. Serial vital capacity and single-breath count are more informative at the bedside, and any deterioration in bulbar function should prompt urgent escalation, not a period of observation.
Reported predictors of post-operative ventilatory requirement include longer disease duration, bulbar involvement, higher pyridostigmine dose and reduced pre-operative vital capacity. These are useful for triage rather than as absolute thresholds, and international consensus guidance emphasises pre-operative optimisation and a low threshold for critical care in patients with bulbar or respiratory involvement.1
Physiotherapy after thymectomy
Two problems overlap: the ordinary consequences of a median sternotomy or thoracoscopic access, and the neuromuscular disorder underneath. The second dictates how the first is treated.
Assessment
- Measure fatigability, not just strength. Repeat a manual test or hold, and record the decrement. A single measurement misrepresents this disease.
- Track vital capacity and cough effectiveness across the day. Weakness classically worsens towards evening.
- Screen swallow and speech. Bulbar weakness drives aspiration risk and predicts respiratory deterioration; involve speech pathology early.
Treatment
- Short sessions, generous rest, submaximal effort. The training principle that works elsewhere — load to fatigue — is actively harmful here. Stop well before failure.
- Time sessions to medication. Work in the window after a pyridostigmine dose, and hand that timing over to the team.
- Assist the cough rather than demanding a stronger one. Manually assisted cough, breath stacking and, where indicated, mechanical insufflation–exsufflation are more appropriate than repeated maximal effort — see Assisted Cough and Cough Assist.
- Observe sternal precautions where a sternotomy was used — see Sternal Precautions. In a patient with proximal weakness, the practical issue is usually getting out of bed without pulling on the arms, which is worth rehearsing.
- Inspiratory muscle training is not established after thymectomy. Evidence in myasthenia gravis is limited to small studies with short follow-up; if used at all, keep loads low and monitor for cumulative fatigue rather than progressing on a schedule.
Role of the physiotherapist
Be the clinician who notices the decrement. Serial vital capacity, cough strength and bulbar function detect a developing crisis before gas exchange does, and a physiotherapist seeing the patient repeatedly through the day is well placed to spot the trend. Pace treatment against the disease rather than against a protocol, protect the sternum, support the cough instead of demanding it, and set the timescale honestly: the operation acts over months, and the first weeks are about avoiding harm rather than gaining ground.
Evidence summary
Framing. Thymectomy is disease-modifying immunotherapy delivered surgically, and its benefit accrues over years while its principal risk is concentrated in the first days. Physiotherapy therefore has two distinct jobs — surveillance for neuromuscular respiratory failure early, and carefully dosed reconditioning later — and the usual overload principle does not transfer.1,2
Evidence — thymectomyMGTX demonstrated that extended transsternal thymectomy plus prednisone improved Quantitative Myasthenia Gravis scores, reduced corticosteroid requirement and lowered hospitalisation for exacerbation over three years in generalised, AChR-antibody-positive, non-thymomatous disease.2 Benefit was maintained in the five-year extension.3 International consensus guidance recommends thymectomy in this population and notes the weaker evidence in antibody-negative disease, purely ocular disease and older patients.1,4
Evidence — the peri-operative riskPost-operative myasthenic crisis is the dominant early risk, and identified associations include bulbar involvement, disease duration, pyridostigmine dose and reduced pre-operative vital capacity; pre-operative plasma exchange or immunoglobulin is used to reduce it.1,5 Oxygenation is an unreliable monitor in neuromuscular respiratory failure, where serial vital capacity and clinical bulbar assessment perform better.6
Physiotherapy implicationsQuantify fatigability rather than peak strength, and repeat measurements across the day. Escalate on falling vital capacity, weakening cough or new bulbar signs rather than waiting for desaturation. Keep sessions short and submaximal, timed to anticholinesterase dosing. Use assisted cough techniques in preference to repeated maximal effort. Treat inspiratory muscle training as unproven in this population and monitor for cumulative fatigue if it is trialled.
Evidence gapsNo trial has examined physiotherapy content, intensity or timing after thymectomy. Exercise prescription in myasthenia gravis rests on small studies with heterogeneous outcomes and no post-surgical data. Whether minimally invasive approaches reproduce the MGTX benefit has not been tested randomly, and the value of thymectomy in antibody-negative and older populations remains unresolved.
References & evidence base
- Narayanaswami P, Sanders DB, Wolfe G, et al. International consensus guidance for management of myasthenia gravis: 2020 update. Neurology 2021;96(3):114–122.
- Wolfe GI, Kaminski HJ, Aban IB, et al; MGTX Study Group. Randomized trial of thymectomy in myasthenia gravis. N Engl J Med 2016;375(6):511–522.
- Wolfe GI, Kaminski HJ, Aban IB, et al; MGTX Study Group. Long-term effect of thymectomy plus prednisone versus prednisone alone in patients with non-thymomatous myasthenia gravis: 2-year extension of the MGTX randomised trial. Lancet Neurol 2019;18(3):259–268.
- Cea G, Benatar M, Verdugo RJ, Salinas RA. Thymectomy for non-thymomatous myasthenia gravis. Cochrane Database Syst Rev 2013;(10):CD008111.
- Wendell LC, Levine JM. Myasthenic crisis. Neurohospitalist 2011;1(1):16–22.
- Racca F, Vianello A, Mongini T, et al. Practical approach to respiratory emergencies in neurological diseases. Neurol Sci 2020;41(3):497–508.
References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.
Physiotherapy around major chest, cardiac and upper abdominal procedures — from open surgery to bronchoscopic, catheter-based and bedside treatments — aims to reduce chest complications and shorten the return to normal function.
Corrections: If something on this page is wrong, out of date or unclear, we want to know. Email reception@inspireclinic.au with the page name and what you believe is incorrect. Substantive corrections are made promptly, and the guide’s version and last-updated date are changed to reflect it.