The Government has been much criticised on several counts for its handling of the pandemic. But perhaps unfairly so, for the most recent mortality figures reveal that Britain, compared with the 32 European countries, has not done too badly, coming halfway down the league table – just below Italy and Belgium and above France and Spain.

The two further considerable achievements to its credit are the roll-out of the vaccination programme – described in a recent parliamentary report as ‘one of the most effective initiatives in UK history’. And then, as recently mentioned in this column, the network of 80 dedicated long Covid clinics for the (estimated) one million people with the persistent debilitating symptoms of fatigue, breathlessness, palpitations, brain fog and so on.

Their primary purpose is to make the necessary distinction between those in whom the symptoms are attributable to the well-recognised post-viral chronic fatigue syndrome or whether they might be due to inflammatory damage to the heart, lungs or other organs. Whereas for the former the key to recovery is rest and the avoidance of undue exertion that can trigger a relapse, those in the latter group may benefit from specific medical therapies.

The many challenges to making that distinction are summarised in a recent review by 33 clinicians from diverse specialities whose expertise is informed, if unusually, by their personal experience of having had long Covid themselves.

The complaint of breathlessness is a case in point – a common feature of post-viral chronic fatigue syndrome but which can also be due to scarring of the lungs, blood clots or inflammatory damage to the heart muscle. Here the simple test of measuring the concentration of oxygen in the blood before and after walking for six minutes provides a useful indication as to who warrants further investigation to identify which might be the culprit.

The review also draws attention to another potentially treatable condition, a post-Covid immunological disorder characterised by an itchy rash, wheeze and bowel disturbance that responds to high doses of antihistamines. For those who might wish to know more, the review is available online.

Musical hallucinations occur mostly in the hearing-impaired

The gentleman much troubled by loud musical hallucinations (“like a Welsh male voice choir at a Six Nations Match”) has prompted numerous and fascinating comments as to their cause and alleviation.

With one very important exception they occur almost invariably in the hearing-impaired and range from the simple (“a constantly repeated pair of notes”) to the full musical repertoire – including, for one woman, Amazing Grace, West Side Story and classical arias; while for others it is variously Paul Robeson singing Ol’ Man River, hymns or carols, string quartets and so on.

The association with deafness is attributed to a “release phenomenon”, where the auditory cortex of the brain, being deprived of the normal sensory input of ambient sounds, is “released” to spontaneously trigger the circuits where the memory of musical sounds are encoded.

The onset of musical hallucinations in those with normal hearing is a very different matter – as mentioned by three readers – where it can be the premonitory symptom of a tumour in the temporal lobe. Gratifyingly, it will usually be benign, but might not be.

As to how best to deal with them, opinions vary. “I favour just listening in as to a concert,” writes one woman, who appreciates “the entertaining choice of music”. But for those in whom they’re intrusive, there is little option other than to “accommodate” them. That means “not being angry or self-pitying at what is happening in my head,” writes another woman. Rather, she adds: “I try to dismiss them so they do not dominate my life.”

Three further points. The extraneous musical sounds may sometimes arise from the Bluetooth facility of modern hearing aids, which can be corrected by switching to airplane mode. Next, it is reported (if rarely) they can be minimised or even abolished by the neurotransmitter drug rivastigmine. Finally, those seeking further advice should contact the Hearing Link helpdesk.

Email medical questions confidentially to Dr James Le Fanu at drjames@telegraph.co.uk