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I'm sorry to hear this, U must be very upset & worried. Praps it is an infection, & will clear - we can only hope.
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As for heritable neuro issues in Lakelands, i have not heard of that as a breed tendency - that doesn't mean it's not there, just that i'm not aware of that as a topic of concern.
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From the AVAR list of heritable problems in purebred dogs, here are the known issues in Lakelands -
Lakeland terrier: 42, 70, 88, 166, 186, 245, 319, 320, 330

Find them listed numerically HERE:
http://www.hsvma.org/assets/pdfs/guide-to-congenital-and-heritable-disorders.pdf
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I hope Maggie recovers well, & U have many-more happy years together. Please keep us posted? - warm pats to Mags.
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Nothing useful to offer but I hope she recovers well.

 

My 11 year old lab keeps lifting his back leg and moving as if to scratch himself, but not making contact with his body... Its like watching him trying to kick start a motor bike...

 

So sorry you are having worrying health issues with your pup. The most common meningitis in younger dogs is usually something called steroid responsive meningitis. The treatment for that is usually high immunosuppressant doses of usually steroids that are given over a considerable period of time and then reduced and tapered off very gradually. They do often also give antibiotics if there is any suggestion that bacterial meningitis or bacterial infection can be involved also. With the correct regime of medication the prognosis is usually very good. A neurologist I saw a few years ago has a special interest in inflammatory brain disease including steroid responsive meningitis and he has written a very good paper on the subject, you can find the link to it and the information below.

http://www.vizslahealth.net/SRMA.pdf

You also asked about neurological issues in Lakelands. Steroid responsive meningitis does seem to have a prevalence in certain breeds ie they are more prone to it, but it can affect any dog usually more often young ones. There is however also a condition called spikes disease, originally named after and sometimes still reffered to as spikes disease after a border terrier spike who first suffered from it and it became recognised, now more recently called Canine Epiletoid cramping syndrome.
I knew that some other terrier type breeds have also been found to suffer from it or similar other then Borders and looking up Lakelands it does seem that they do suffer with it too. It does seem that not all vets are aware of the condition, and maybe not so much with Lakelands as at first it seemed to be a Border terrier issue.
The link below is about Spikes/Canine Epiletoid Cramping syndrome in general and also give more specific info about the condition in Lakelands as its a Lakeland specific website.

https://lakelandterriertopics.wordpress.com/health-issues/spikes-disease/

In addition to this, the same Lakeland specific information website also gives information about epilepsy in the breed too.
https://lakelandterriertopics.wordpress.com/health-issues/epilepsy/

The only other suggestion I could make would be perhaps to ask your vet to do you a referral to a canine neurology specialist. Hope this information may be of some use, and also hope there is improvement in your puppy quickly.