When battery exhaustion lets the lame walk: a case report on the importance of long-term stimulator monitoring in deep brain stimulation

A 74-year-old, retired teacher with a 20-year history of idiopathic Parkinson’s disease
had undergone bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) in
a centre with experience in the method. We first saw him seven years after the implantation
when he presented in our clinic to have the device transiently switched off for scheduled
dental surgery. He was wheelchair-bound outside his home and used a walking frame
at home. His caregiver reported that he fell frequently, and he was dysarthric to
an extent that almost completely hindered oral communication. The UPDRS III score
was 32 of a possible 108 points; the DBS settings were 130 Hz with 60 microseconds
pulse width and monopolar setting with the second deepest electrode contact on each
side acting as cathode and the case acting as anode with an amplitude of 2.5 V in
the right and 3.0 V in the left hemisphere. He was on medication with levodopa, entacapone,
and pramipexole divided into seven daily doses, with a total levodopa equivalent dose
of 998 mg 7], oral quetiapine 25 mg at night-time for his visual hallucinations, as well as oral
rivastigmine 3 mg in the morning for dementia. The Kinetra® battery capacity was indicated
as “OK” with a voltage of 2,56 V and 40–90 % of the capacity used.

Five months after our first contact, the patient’s caregiver contacted the first author
and reported that the patient was surprisingly able to walk independently, and that
the clarity of this speech had improved markedly. She also reported that the deep
brain stimulator no longer responded to the patient’s controlling device.

We confirmed that the battery was exhausted. He was able to speak intelligibly with
mild hypophonia. Rising from chair was fast, but postural responses were markedly
reduced, resulting in a very unsteady, albeit independent gait over a distance of
several meters. The UPDRS part III score was 24. He was now on medication with levodopa,
entacapone and pramipexole every four hours, with a total levodopa equivalent dose
of 1182 mg, oral quetiapine 25 mg at night-time and a rivastigmine patch 9 mg in the
morning.

Expecting a relapse and worsening of the parkinsonian symptoms in the foreseeable
future, we implanted an Activa PC ® device and left the stimulator off until his clinical
condition should worsen. To avoid falls, we recommended that he walk only with assistance
and with a walking frame.

After a further four months the patient presented with increasingly incapacitating
fluctuations of motor function that made walking with the frame more and more difficult,
indicating further disease progression. The other motor symptoms were stable except
for a slight worsening of his hypophonia and very poor postural stability, resulting
in a UPDRS part III score of 27. We carefully retested the electrodes and opted for
a bipolar setting in the left hemisphere with contact 3 negative and contact 2 positive
at 3.5 V, and a monopolar setting in the right hemisphere with the deepest contact
7 as cathode and the case as anode at 2.0 V, with 130 Hz frequency and 60 microseconds
pulse width bilaterally. We discharged the patient with less pronounced dyskinesias,
and medication with levodopa, entacapone and pramipexole in eight doses over the day,
with a total levodopa equivalent dose of 1182 mg, oral quetiapine 25 mg at night-time,
and oral rivastigmine 3 mg three times daily.