Dystonia

INDEX

Tremor is very commonly seen in cervical dystonia, and correlates with the duration and severity of the dystonia.

The most common subtype seen is torticaput, possibly related to greater involvement of antagonistic muscles being active in this particulary subtype, antagonistic muscles being passively tensed by abnormal movements/postures.
Laterocaput and laterocollis are less commonly seen.

Bilateral injections are usually performed in muscles that are active synchronously to tremor.. 
If there is a clearly recognizable directional preponderance, as in jerky head tremors, muscle selection will take into account the most prevalent direction of pulling of the head.

No-No tremor

No-no: OCI typically involved.

For no‐no tremor, the initial dose for this muscle is 10‐20 units of onabotulinumtoxinA per side (total dose 20‐40 units),

Traditinally injected muscles include:

Splenius capitis - 2x50U,  2 x 10-12.5 u max 60 u Botox or 2 x 40-50 U Dysport , max 250 U

Semispinalis capitis 2x20-30U

Video 1. Tremulous OCI in a patient with head tremor

(vv)44.mp4 (tt)

From: Fietzek UM, Nene D, Schramm A, Appel-Cresswell S, Košutzká Z, Walter U, Wissel J, Berweck S, Chouinard S, Bäumer T. The Role of Ultrasound for the Personalized Botulinum Toxin Treatment of Cervical Dystonia. Toxins (Basel). 2021 May 20;13(5):365. 

 

Yes-Yes tremor

Muscles for injection include:

Semispinalis capitis 2x20-30U
Include SCM 2  x 20 IE bilateral
Consider splenius capitis  (2 x 10-12.5, max 60 u Botox OR 2 x 40-50 u Dysport, max 250 u)

For some head tremors, the levator scapulae and the longissimus capitis may also be injected.
    

References

  1. Pandey S, Kreisler A, Drużdż A, Biering-Sørensen B, Sławek J, Tatu L, Jost WH. Tremor in Idiopathic Cervical Dystonia - Possible Implications for Botulinum Toxin Treatment Considering the Col-Cap Classification. Tremor Other Hyperkinet Mov (N Y). 2020 Jul 7;10:13.